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  #1   Report Post  
John Aston
 
Posts: n/a
Default Heating design diagram (preliminary)

Thanks for your help to date. I've distilled the advice from various threads
in this newsgroup to come up with a possible heating design for my house.

The drawing HD01 at http://tinyurl.com/3zv2g shows the proposed hydraulic
design for a large domestic heating system. The boiler and hot water
cylinder is on the left hand side of the drawing, space heating is on the
right. (You might need to rotate the view so that the drawing is in
landscape orientation in your browser)

Some explanatory notes on the design are appended below. Any comments would
be gratefully received but my principal questions a

(1) The internal space heating requirement when it's -3°C outside is 31kW.
In addition, there is a 250L cylinder serving three showers and one bath for
a family of five. Is a 38kW boiler sufficient?

(2) I'm specifying 28mm pipe through the water softener and up to the
cylinder, 22mm for the boiler flow and return, 22mm to potable water cold
taps and 15mm everywhere else. Is that reasonable or over the top?

(3) A 22mm pipe is teed off the secondary side of the low loss header. From
this 22mm pipe, I propose to tee off 15mm pipe to each heating zone. What is
the maximum distance between these 15mm tees, and what's the maximum
permissible distance from the furthest 15mm tee to the header? (Keston told
me that there is NO restriction)

(4) What's the best way of incorporating two towel rails (bottom right) into
the circuit so that the towel rails come on all year round when there is
either a call for heat or a call for hot water?

Design:

The mains cold water supply is treated by a water softener (bottom left).
The softened water is fed to a 250L cylinder under pressure from an
accumulator which keeps the cold water at about 2.5 bar and provides a high
flow rate to all taps.

The water in the cylinder is heated indirectly by the primary of a 38kW
fully-modulating condensing boiler in the room below the cylinder. Hot water
is circulated to the taps by means of a secondary pump. Because the system
is unvented, the hot water is also at a pressure of about 2.5 bar.

A diverter valve allows the boiler to heat the central heating system when
there is no demand for heating from the cylinder. The boiler flow is
diverted into a low loss header from which the distribution circuits
(heating zones) are pumped. The header buffers the boiler primary control
against sudden changes of flow in the distribution circuits.

The central heating system comprises both underfloor heating and radiators
in all rooms (only a few rooms A-E are shown, for clarity). There are two
heating zones: The kitchen and reception rooms on the ground floor are zone
1, and the upstairs bedrooms and bathrooms are zone 2. Since each zone
comprises one underfloor heating system and one set of radiators, there are
a total of 2 x 2 = 4 heating distribution circuits.

The underfloor heating circuits are connected to a manifold and
temperature-controlled by room thermostats which operate the circuit valves.
The water through the underfloor heating system is limited to 55°C maximum
by a thermostatic mixing valve at the manifold entry. The underfloor heating
has a maximum output of 17kW and is only capable of maintaining a internal
temperature of 9°C or 10°C above the outside temperature.

The purpose of the radiators is to supplement the underfloor heating with up
to 14kW additional heat when the external temperatures are cold. The
temperature of the water pumped to the radiators is (almost) equal to the
temperature in the low loss header. The boiler's primary flow temperature is
a function of the outside temperature and typically falls from 70°C to 40°C
when the outside temperature rises from 0°C to 15°C. The radiators are
switched on and off by thermostatic valves.

Every underfloor heating circuit has its own room thermostat and the
circuits are terminated at a manifold which has its own local controller
that sends a signal to the master controller when there is a call for
underfloor heat. The master controller has provision for switching the hot
water and heating off independently at user-adjustable times.

The system has a distribution of drain cocks and isolation valves to simply
maintenance.

Sources of information:
This newsgroup and, amongst others,
Viessmann http://tinyurl.com/6cqtt (Page 41)
Geminox http://tinyurl.com/5glxs (Bottom of page 7)
MAN Heiztechnik http://tinyurl.com/3vzwz (Page 27)


  #2   Report Post  
Set Square
 
Posts: n/a
Default

In an earlier contribution to this discussion,
John Aston wrote:

Thanks for your help to date. I've distilled the advice from various
threads in this newsgroup to come up with a possible heating design
for my house.

The drawing HD01 at http://tinyurl.com/3zv2g shows the proposed
hydraulic design for a large domestic heating system. The boiler and
hot water cylinder is on the left hand side of the drawing, space
heating is on the right. (You might need to rotate the view so that
the drawing is in landscape orientation in your browser)


Wonderful - but who's going to understand it when you're not around?

Incidentally, what's the 'top-up' tank in the primary circuit for - bearing
in mind that it's a pressurised system with pressure vessel and filling
loop?
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.


  #3   Report Post  
Rob Morley
 
Posts: n/a
Default

In article , "Set Square"
says...
In an earlier contribution to this discussion,
John Aston wrote:

Thanks for your help to date. I've distilled the advice from various
threads in this newsgroup to come up with a possible heating design
for my house.

The drawing HD01 at
http://tinyurl.com/3zv2g shows the proposed
hydraulic design for a large domestic heating system. The boiler and
hot water cylinder is on the left hand side of the drawing, space
heating is on the right. (You might need to rotate the view so that
the drawing is in landscape orientation in your browser)


Wonderful - but who's going to understand it when you're not around?

Incidentally, what's the 'top-up' tank in the primary circuit for - bearing
in mind that it's a pressurised system with pressure vessel and filling
loop?

So you can get additives into the system easily?
  #4   Report Post  
John Aston
 
Posts: n/a
Default

Set Square wrote in message
...

Wonderful - but who's going to understand it when you're not around?


I'll leave my inheritors the Google Groups link to this thread

Incidentally, what's the 'top-up' tank in the primary circuit for -

bearing
in mind that it's a pressurised system with pressure vessel and filling
loop?


You're right - I don't really need the tank. I had half a mind to use it to
monitor the volume of water that had escaped from the system so that I could
assess whether there were any leaks.


  #5   Report Post  
IMM
 
Posts: n/a
Default


"John Aston" wrote in message
.. .
Thanks for your help to date. I've distilled the advice from various

threads
in this newsgroup to come up with a possible heating design for my house.

The drawing HD01 at http://tinyurl.com/3zv2g shows the proposed hydraulic
design for a large domestic heating system. The boiler and hot water
cylinder is on the left hand side of the drawing, space heating is on the
right. (You might need to rotate the view so that the drawing is in
landscape orientation in your browser)

Some explanatory notes on the design are appended below. Any comments

would
be gratefully received but my principal questions a

(1) The internal space heating requirement when it's -3°C outside is 31kW.
In addition, there is a 250L cylinder serving three showers and one bath

for
a family of five. Is a 38kW boiler sufficient?

(2) I'm specifying 28mm pipe through the water softener and up to the
cylinder, 22mm for the boiler flow and return, 22mm to potable water cold
taps and 15mm everywhere else. Is that reasonable or over the top?

(3) A 22mm pipe is teed off the secondary side of the low loss header.

From
this 22mm pipe, I propose to tee off 15mm pipe to each heating zone. What

is
the maximum distance between these 15mm tees, and what's the maximum
permissible distance from the furthest 15mm tee to the header? (Keston

told
me that there is NO restriction)

(4) What's the best way of incorporating two towel rails (bottom right)

into
the circuit so that the towel rails come on all year round when there is
either a call for heat or a call for hot water?

Design:

The mains cold water supply is treated by a water softener (bottom left).
The softened water is fed to a 250L cylinder under pressure from an
accumulator which keeps the cold water at about 2.5 bar and provides a

high
flow rate to all taps.

The water in the cylinder is heated indirectly by the primary of a 38kW
fully-modulating condensing boiler in the room below the cylinder. Hot

water
is circulated to the taps by means of a secondary pump. Because the system
is unvented, the hot water is also at a pressure of about 2.5 bar.

A diverter valve allows the boiler to heat the central heating system when
there is no demand for heating from the cylinder. The boiler flow is
diverted into a low loss header from which the distribution circuits
(heating zones) are pumped. The header buffers the boiler primary control
against sudden changes of flow in the distribution circuits.

The central heating system comprises both underfloor heating and radiators
in all rooms (only a few rooms A-E are shown, for clarity). There are two
heating zones: The kitchen and reception rooms on the ground floor are

zone
1, and the upstairs bedrooms and bathrooms are zone 2. Since each zone
comprises one underfloor heating system and one set of radiators, there

are
a total of 2 x 2 = 4 heating distribution circuits.

The underfloor heating circuits are connected to a manifold and
temperature-controlled by room thermostats which operate the circuit

valves.
The water through the underfloor heating system is limited to 55°C maximum
by a thermostatic mixing valve at the manifold entry. The underfloor

heating
has a maximum output of 17kW and is only capable of maintaining a internal
temperature of 9°C or 10°C above the outside temperature.

The purpose of the radiators is to supplement the underfloor heating with

up
to 14kW additional heat when the external temperatures are cold. The
temperature of the water pumped to the radiators is (almost) equal to the
temperature in the low loss header. The boiler's primary flow temperature

is
a function of the outside temperature and typically falls from 70°C to

40°C
when the outside temperature rises from 0°C to 15°C. The radiators are
switched on and off by thermostatic valves.

Every underfloor heating circuit has its own room thermostat and the
circuits are terminated at a manifold which has its own local controller
that sends a signal to the master controller when there is a call for
underfloor heat. The master controller has provision for switching the hot
water and heating off independently at user-adjustable times.

The system has a distribution of drain cocks and isolation valves to

simply
maintenance.

Sources of information:
This newsgroup and, amongst others,
Viessmann http://tinyurl.com/6cqtt (Page 41)
Geminox http://tinyurl.com/5glxs (Bottom of page 7)
MAN Heiztechnik http://tinyurl.com/3vzwz (Page 27)


I'll get back tomorrow . Have been out a lot today.




  #6   Report Post  
Aidan
 
Posts: n/a
Default

"John Aston" wrote in message ...
Thanks for your help to date. I've distilled the advice from various threads
in this newsgroup to come up with a possible heating design for my house.

The drawing HD01 at http://tinyurl.com/3zv2g shows the proposed hydraulic
design



Ooh, lovely. You'd said you were a plumbing amateur. Ha, ha! You've
done this before, haven't you.

Suggestions;
1) Put a DCV between the drinking water and the softener. The DCV
shown protects the mains, but not the drinking water from
contamination by the softener.
2) 15mm should be plenty for the drinking water.
3) Softener. You'd need a duplex model, with two resin vessels, to
ensure a softened supply at all times. A duplex softener would
regenerate as required by a meter, so would minimize the salt
consumption; costs more, though. The resin takes a 1 to 1.5 hours to
regenerate. Softened water at 0ppm can pinhole copper hot water pipes
in 2 or 3 years. A blending by-pass valve to give 40ppm is advisable,
but you'd need a serious test-kit.
4) The PRV symbols are the wrong way round. The symbol is derived from
steam PRVs which have small HP inlet pipes and large LP outlet pipes.
Pedant mode off.
5) Don't fill the heating with softened water. The fill water will
contain a minute amount of limescale, but softened water causes some
problem with the inhibitors which I can't recall.
6) You don't want a PRV upstream of the accumulator. The idea is to
accumulate a volume of water under pressure. A PRV downstream is OK.
7) I'd add the accumulator at a later date, if it proved necessary.
8) The PRV on the unvented HWS usually has a second outlet port for a
balanced pressure cold supply. The strainer should be upstream of the
PRV; often it's integral with it. The whole set of components comes
with the cylinder 'package'.
9) Given the size of this system, I would consider supplying the DHWS
cylinder with a pump (making 6) from the secondary side of the low
loss header.
10) On the low loss header, the temperature sensor has to be immersed
in the flow water and the primary & secondary pipes need to be
off-set. This is a schematic drawing, so they probably will be.
11) There would be IVs on the flow connections to the UFH headers.
These often have flow indicators to facilitate balancing.
12) On the heating flow connections, I'd put the CVs downstream of the
IVs. It makes no difference to the function, but you could service a
defective CV without draining the entire system.
13) You need IVs on the heating returns from the rad circuits, before
they connect to the 22mm secondary return header pipe. I'd put all the
IVs adjacent to the secondary header pipes.
14) Is 22mm pipe big enough for the secondary header pipes? There
should be a negligible pressure loss at the design flow rate.
15) Why do you need a control valve upstream of the mixing valves?
16) Towel rails; another pump, I'd think, No.7. There's some EU
regulation requiring low temperatures to towel rails, but I don't
recall the details.
17) You don't need the top-up tank, you can add inhibitors through a
radiator. A drain valve on a rad, after the rad valves, for this would
be useful.
18) I don't think you need more than one pressure gauge.


Stick it on The Wall at Heatinghelp and invite comments. There are
photos of similar systems posted there regularly. They appreciate this
sort of thing. Tell them you're a first-time amateur!


Is a 38kW boiler sufficient?

It depends entirely on the heat losses. No other response would be
sensible.

Wonderful - but who's going to understand it when you're not around?


Me.
I have a schematic somewhere that I once drew of an existing heating
system. It takes up an A0 sheet. Some details are difficult to read at
that size.
  #8   Report Post  
John Aston
 
Posts: n/a
Default


Aidan wrote in message
om...
"John Aston" wrote in message

...
Thanks for your help to date. I've distilled the advice from various

threads
in this newsgroup to come up with a possible heating design for my

house.

The drawing HD01 at http://tinyurl.com/3zv2g shows the proposed

hydraulic
design



Ooh, lovely. You'd said you were a plumbing amateur. Ha, ha! You've
done this before, haven't you.


No, honestly! It's really the result of pouring over the manufacturers'
instructions and trying to piece it all together.

Suggestions;
1) Put a DCV between the drinking water and the softener. The DCV
shown protects the mains, but not the drinking water from
contamination by the softener.


OK. I was worried about a drop in the pressure/flow rate. My incoming supply
is only 2.8 bar static and 30lpm.

2) 15mm should be plenty for the drinking water.


OK, thanks

3) Softener. You'd need a duplex model, with two resin vessels, to
ensure a softened supply at all times. A duplex softener would
regenerate as required by a meter, so would minimize the salt
consumption; costs more, though. The resin takes a 1 to 1.5 hours to
regenerate. Softened water at 0ppm can pinhole copper hot water pipes
in 2 or 3 years. A blending by-pass valve to give 40ppm is advisable,
but you'd need a serious test-kit.


The softener I had in mind was a Kinetico 2020c HF which uses two
resin-filled cylinders alternately to give a flow rate of 51 lpm at 2 bar. I
never knew its effect on copper pipes! I'm surprised they don't mention it


4) The PRV symbols are the wrong way round. The symbol is derived from
steam PRVs which have small HP inlet pipes and large LP outlet pipes.
Pedant mode off.
5) Don't fill the heating with softened water. The fill water will
contain a minute amount of limescale, but softened water causes some
problem with the inhibitors which I can't recall.


Thanks, I'll change the above in the second draft.

6) You don't want a PRV upstream of the accumulator. The idea is to
accumulate a volume of water under pressure. A PRV downstream is OK.


The upstream PRV is part of a combination valve that is supplied with the
Dualstream cylinder and accumulator. I guess it's set at 3.5 bar to comply
with regulations. It might be easier to leave out the downstream PRV. The
mains static pressure is only 2.8 bar anyway.

7) I'd add the accumulator at a later date, if it proved necessary.


Yes. If the vendor allows me to buy an accumulator without the cylinder,
I'll plumb for it as a future addition.

8) The PRV on the unvented HWS usually has a second outlet port for a
balanced pressure cold supply. The strainer should be upstream of the
PRV; often it's integral with it. The whole set of components comes
with the cylinder 'package'.


You're right about the package. My drawing has shown the individual
components really just for my own understanding. I'll reverse the position
of the PRV and strainer.

9) Given the size of this system, I would consider supplying the DHWS
cylinder with a pump (making 6) from the secondary side of the low
loss header.


I did think about this but
(a) The cylinder is less than 8m pipe length from the boiler so I hoped that
the boiler pump could get the water there on its own.
(b) The cylinder water will be pumped from the boiler at 80°C and the water
through the heating circuits will typically be at 50-60°C. I didn't want the
header to cycle between the low and high temperatures when the boiler heated
up the cylinder. I thought that that might be less efficient.

10) On the low loss header, the temperature sensor has to be immersed
in the flow water and the primary & secondary pipes need to be
off-set. This is a schematic drawing, so they probably will be.


Yes, you're right. The header is a pre-fabricated assembly.

11) There would be IVs on the flow connections to the UFH headers.
These often have flow indicators to facilitate balancing.


I'm hoping that these come as part of the manifold from the UFH suppliers

12) On the heating flow connections, I'd put the CVs downstream of the
IVs. It makes no difference to the function, but you could service a
defective CV without draining the entire system.


Thanks, I'll change their position in the second draft.

13) You need IVs on the heating returns from the rad circuits, before
they connect to the 22mm secondary return header pipe. I'd put all the
IVs adjacent to the secondary header pipes.


OK. I'll add these

14) Is 22mm pipe big enough for the secondary header pipes? There
should be a negligible pressure loss at the design flow rate.


Pipe diameter is an area of uncertainty for me. Also, you can see on the
diagram that I've written MAX. DISTANCE? I can't get any definitive answers
(or even rule of thumb) from the boiler manufacturers.

15) Why do you need a control valve upstream of the mixing valves?


The UFH heating circuits have their own individual themostats. If one room
gets up to temperature, it can close down its circuit's valve, but still let
the other circuits on the manifold heat up.

16) Towel rails; another pump, I'd think, No.7. There's some EU
regulation requiring low temperatures to towel rails, but I don't
recall the details.


Yes, another pump is probably the way although, with the way I've drawn it,
in Summer the boiler would have to heat up the header just for the towel
rails. I can live with this, I guess.

17) You don't need the top-up tank, you can add inhibitors through a
radiator. A drain valve on a rad, after the rad valves, for this would
be useful.
18) I don't think you need more than one pressure gauge.


OK. I think that they come as part of the UFH manifold.


Stick it on The Wall at Heatinghelp and invite comments. There are
photos of similar systems posted there regularly. They appreciate this
sort of thing. Tell them you're a first-time amateur!


I'll make the changes and do this.

Is a 38kW boiler sufficient?

It depends entirely on the heat losses. No other response would be
sensible.


The heat losses would be 31kW. I'm hoping that the additional 7kW will give
me some headroom plus a bit for the domestic hot water.

Thanks, Aidan. You're a gentleman.




  #9   Report Post  
Dave Plowman (News)
 
Posts: n/a
Default

In article ,
IMM wrote:
I'll get back tomorrow . Have been out a lot today.


Lots of deliveries this time of year.

--
*Work is for people who don't know how to fish.

Dave Plowman London SW
To e-mail, change noise into sound.
  #10   Report Post  
IMM
 
Posts: n/a
Default


"Dave Plowman (News)" wrote in message
...
In article ,
IMM wrote:
I'll get back tomorrow . Have been out a lot today.


Lots of deliveries this time of year.


Deliverables are in order.




  #11   Report Post  
IMM
 
Posts: n/a
Default


"John Aston" wrote in message
.. .

Aidan wrote in message
om...
"John Aston" wrote in message

...
Thanks for your help to date. I've distilled the advice from various

threads
in this newsgroup to come up with a possible heating design for my

house.

The drawing HD01 at http://tinyurl.com/3zv2g shows the proposed

hydraulic
design



Ooh, lovely. You'd said you were a plumbing amateur. Ha, ha! You've
done this before, haven't you.


No, honestly! It's really the result of pouring over the manufacturers'
instructions and trying to piece it all together.

Suggestions;
1) Put a DCV between the drinking water and the softener. The DCV
shown protects the mains, but not the drinking water from
contamination by the softener.


OK. I was worried about a drop in the pressure/flow rate. My incoming

supply
is only 2.8 bar static and 30lpm.

2) 15mm should be plenty for the drinking water.


OK, thanks

3) Softener. You'd need a duplex model, with two resin vessels, to
ensure a softened supply at all times. A duplex softener would
regenerate as required by a meter, so would minimize the salt
consumption; costs more, though. The resin takes a 1 to 1.5 hours to
regenerate. Softened water at 0ppm can pinhole copper hot water pipes
in 2 or 3 years. A blending by-pass valve to give 40ppm is advisable,
but you'd need a serious test-kit.


The softener I had in mind was a Kinetico 2020c HF which uses two
resin-filled cylinders alternately to give a flow rate of 51 lpm at 2 bar.

I
never knew its effect on copper pipes! I'm surprised they don't mention it


4) The PRV symbols are the wrong way round. The symbol is derived from
steam PRVs which have small HP inlet pipes and large LP outlet pipes.
Pedant mode off.
5) Don't fill the heating with softened water. The fill water will
contain a minute amount of limescale, but softened water causes some
problem with the inhibitors which I can't recall.


Thanks, I'll change the above in the second draft.

6) You don't want a PRV upstream of the accumulator. The idea is to
accumulate a volume of water under pressure. A PRV downstream is OK.


The upstream PRV is part of a combination valve that is supplied with the
Dualstream cylinder and accumulator. I guess it's set at 3.5 bar to comply
with regulations.


No. To protect the unvented cylinder. A heat bank with a plate heat
exchanger can go to about 10 bar.

It might be easier to leave out the downstream PRV. The
mains static pressure is only 2.8 bar anyway.

7) I'd add the accumulator at a later date, if it proved necessary.


Yes. If the vendor allows me to buy an accumulator without the cylinder,
I'll plumb for it as a future addition.

8) The PRV on the unvented HWS usually has a second outlet port for a
balanced pressure cold supply. The strainer should be upstream of the
PRV; often it's integral with it. The whole set of components comes
with the cylinder 'package'.


You're right about the package. My drawing has shown the individual
components really just for my own understanding. I'll reverse the position
of the PRV and strainer.

9) Given the size of this system, I would consider supplying the DHWS
cylinder with a pump (making 6) from the secondary side of the low
loss header.


I did think about this but
(a) The cylinder is less than 8m pipe length from the boiler so I hoped

that
the boiler pump could get the water there on its own.
(b) The cylinder water will be pumped from the boiler at 80°C and the

water
through the heating circuits will typically be at 50-60°C. I didn't want

the
header to cycle between the low and high temperatures when the boiler

heated
up the cylinder. I thought that that might be less efficient.

10) On the low loss header, the temperature sensor has to be immersed
in the flow water and the primary & secondary pipes need to be
off-set. This is a schematic drawing, so they probably will be.


Yes, you're right. The header is a pre-fabricated assembly.

11) There would be IVs on the flow connections to the UFH headers.
These often have flow indicators to facilitate balancing.


I'm hoping that these come as part of the manifold from the UFH suppliers

12) On the heating flow connections, I'd put the CVs downstream of the
IVs. It makes no difference to the function, but you could service a
defective CV without draining the entire system.


Thanks, I'll change their position in the second draft.

13) You need IVs on the heating returns from the rad circuits, before
they connect to the 22mm secondary return header pipe. I'd put all the
IVs adjacent to the secondary header pipes.


OK. I'll add these

14) Is 22mm pipe big enough for the secondary header pipes? There
should be a negligible pressure loss at the design flow rate.


Pipe diameter is an area of uncertainty for me. Also, you can see on the
diagram that I've written MAX. DISTANCE? I can't get any definitive

answers
(or even rule of thumb) from the boiler manufacturers.

15) Why do you need a control valve upstream of the mixing valves?


The UFH heating circuits have their own individual themostats. If one room
gets up to temperature, it can close down its circuit's valve, but still

let
the other circuits on the manifold heat up.

16) Towel rails; another pump, I'd think, No.7. There's some EU
regulation requiring low temperatures to towel rails, but I don't
recall the details.


Yes, another pump is probably the way although, with the way I've drawn

it,
in Summer the boiler would have to heat up the header just for the towel
rails. I can live with this, I guess.

17) You don't need the top-up tank, you can add inhibitors through a
radiator. A drain valve on a rad, after the rad valves, for this would
be useful.
18) I don't think you need more than one pressure gauge.


OK. I think that they come as part of the UFH manifold.


Stick it on The Wall at Heatinghelp and invite comments. There are
photos of similar systems posted there regularly. They appreciate this
sort of thing. Tell them you're a first-time amateur!


I'll make the changes and do this.

Is a 38kW boiler sufficient?

It depends entirely on the heat losses. No other response would be
sensible.


The heat losses would be 31kW. I'm hoping that the additional 7kW will

give
me some headroom plus a bit for the domestic hot water.

Thanks, Aidan. You're a gentleman.






  #12   Report Post  
IMM
 
Posts: n/a
Default


"John Aston" wrote in message
.. .

Thanks for your help to date. I've distilled the advice from various

threads
in this newsgroup to come up with a possible heating design for my house.

The drawing HD01 at http://tinyurl.com/3zv2g shows the proposed hydraulic
design for a large domestic heating system. The boiler and hot water
cylinder is on the left hand side of the drawing, space heating is on the
right. (You might need to rotate the view so that the drawing is in
landscape orientation in your browser)


Aiden has highlighted some points, so I will not go over them. Some
observations and Qs:

Firstly, what drawing package did you use, Visio?

The boiler appears to be a Veissmann with an in-built outside weather
compensator with the temp sensor in the low loss header. If the compensator
slope is set to the UFH, it will not be suitable for the rads. You would
require the low loss header to be on the minimum temp that the rads take,
which means a higher temperature for the boiler to operate on making it
less efficient. If you set the compensator slope for the higher temp rads,
each the UFH zone will control itself on its own mixer controls, set to
maximum of 55C.

You could use a dual temp boiler as the Eco-Hometec, or a simple boiler
maintaining a hot low loss header at a high temp. This is what is done with
non-compensating boilers where the return temp "has" to be high. So, as you
have it the rads will not go about 55C.

The mains water from the accumulator. As you have done in splitting the DHW
supply to the cylinder after the accumulator, and cold water. But! have
all cold taps off one leg. On the other supply only the cylinder. With the
exception of just before the cylinder have the cold supplies to the showers
only.

Have only one pressure reducing valve as mixers require equal pressure on
each inlet line. Using an accumulator means you only need cheap shower
mixers.

If you assess the heating requirement to 32Kw then stick to this, or the
nearest to, depending on price. No need to go over for DHW as you have a
priority system. This diverts all the boilers heat to the cylinder.

Make sure the cylinder is quick recovery. Unvented cylinders are never as
quick as vented or thermal stores. The coils are restricted so as not to
generate too much pressure inside.

Do you still intend to have two stage heating? UFH with rads boosting?
Yiou have 5 UFH ziones. Where will the rads fit in relating to these zones?

Back to having differing temps for rads and UFH. As it is, efficiency is
compromised by the high temp rad circuits. You have an efficient expensive
boiler not performing to maximum potential. Look at the low loss header on
the diagram. Replace this with a heat bank/thermal store. Off the bottom
UFH section of the thermal store have the UFH circuits. Off the high temp
top section have the rads and DHW. You may want to have three sections: top
DHW, middle rads, bottom UFH. Then you have all circuits coming into a
neutral point, the heat bank.

Now you have greater control of temperatures, dividing and ruling, which
means the boiler will not be running at too high a temperature to suit only
the rads compromising efficiency. An outside weather compensator can be on
the UFH section to keep this part of the store at the ideal high efficient
low temperature and prevent boiler cycling. You may want a compensator on a
heat bank mid section serving the rads (UFH & rads have different slopes).

Using a heat bank, a far cheaper and simpler boiler may be used.

Having three sections means that in summer, only the DHW top section is
heated, not the whole store, saving on standing losses.

Using a heat bank immersions may be fitted in the different temperature
sections. So, if there is a boiler outage you can run the whole system,
heating and DHW off electricity. You can't do that with a boiler connected
via a low loss heater.

Towel rails: These can be teed in before the diverter valve at the boiler,
between valve and pump and direct to the return. They will then work in
summer, but only when the cylinder or heat bank is being re-heated, which is
fine for summer use. If you take a shower and the boiler kicks in the
re-heat you will find the towels are hot on the rails.

Accumulator: If they will not sell unless they supply the unvented cylinder
(they would sell one separately to me), keep a tank in the loft and have a
booster pump serving a heat bank. This is a cheaper an simpler option too.
The tank does not need to be in the loft. It can be anywhere as it is
pumped.

It would be interesting to see what the Yanks say. They don't do thermal
stores in a big way there and thinking tends to be 1950ish, so only regard
what they say as interest only.

Simpler Alternative:

1. Low Temp Circuit: One dedicated condensing boiler serving the UFH only
on a weather compensator. Simple, separate and sorted.

2. High temp circuit. Another boiler using a 3-way diverter valve serving
DHW and rads. You may want a weather compensator switching the boikler to
give the ideal temp for the rads. When DHW is called the boiler runs up to
max temp. This is similar to normal domestic setup.

3. A controller staging in the UFH and rads to give precise control of room
temps. UFH 1st stage.

4. Backup: Now you have heating backup if one boiler drops out.
Electrical backup for DHW.

5. Cold water storage tank instead of an accumulator with a booster pump.
Tank can be fitted anywhere.

6. The cylinder can be:

a) An unvented version,

b) A DHW only heat bank, such the DPS Pandora, which does requires an
overflow so can be fitted anywhere in the house.

You will find that two condensing boilers can be had for less than the price
of the Viessmann, and lots of change too.



  #13   Report Post  
IMM
 
Posts: n/a
Default


"IMM" wrote in message
...

"John Aston" wrote in message
.. .

Thanks for your help to date. I've distilled the advice from various

threads
in this newsgroup to come up with a possible heating design for my

house.

The drawing HD01 at http://tinyurl.com/3zv2g shows the proposed

hydraulic
design for a large domestic heating system. The boiler and hot water
cylinder is on the left hand side of the drawing, space heating is on

the
right. (You might need to rotate the view so that the drawing is in
landscape orientation in your browser)


Aiden has highlighted some points, so I will not go over them. Some
observations and Qs:

Firstly, what drawing package did you use, Visio?

The boiler appears to be a Veissmann with an in-built outside weather
compensator with the temp sensor in the low loss header. If the

compensator
slope is set to the UFH, it will not be suitable for the rads. You would
require the low loss header to be on the minimum temp that the rads take,
which means a higher temperature for the boiler to operate on making it
less efficient. If you set the compensator slope for the higher temp rads,
each the UFH zone will control itself on its own mixer controls, set to
maximum of 55C.

You could use a dual temp boiler as the Eco-Hometec, or a simple boiler
maintaining a hot low loss header at a high temp. This is what is done

with
non-compensating boilers where the return temp "has" to be high. So, as

you
have it the rads will not go about 55C.

The mains water from the accumulator. As you have done in splitting the

DHW
supply to the cylinder after the accumulator, and cold water. But! have
all cold taps off one leg. On the other supply only the cylinder. With

the
exception of just before the cylinder have the cold supplies to the

showers
only.

Have only one pressure reducing valve as mixers require equal pressure on
each inlet line. Using an accumulator means you only need cheap shower
mixers.

If you assess the heating requirement to 32Kw then stick to this, or the
nearest to, depending on price. No need to go over for DHW as you have a
priority system. This diverts all the boilers heat to the cylinder.

Make sure the cylinder is quick recovery. Unvented cylinders are never as
quick as vented or thermal stores. The coils are restricted so as not to
generate too much pressure inside.

Do you still intend to have two stage heating? UFH with rads boosting?
Yiou have 5 UFH ziones. Where will the rads fit in relating to these

zones?

Back to having differing temps for rads and UFH. As it is, efficiency is
compromised by the high temp rad circuits. You have an efficient expensive
boiler not performing to maximum potential. Look at the low loss header

on
the diagram. Replace this with a heat bank/thermal store. Off the bottom
UFH section of the thermal store have the UFH circuits. Off the high temp
top section have the rads and DHW. You may want to have three sections:

top
DHW, middle rads, bottom UFH. Then you have all circuits coming into a
neutral point, the heat bank.

Now you have greater control of temperatures, dividing and ruling, which
means the boiler will not be running at too high a temperature to suit

only
the rads compromising efficiency. An outside weather compensator can be

on
the UFH section to keep this part of the store at the ideal high efficient
low temperature and prevent boiler cycling. You may want a compensator on

a
heat bank mid section serving the rads (UFH & rads have different slopes).

Using a heat bank, a far cheaper and simpler boiler may be used.

Having three sections means that in summer, only the DHW top section is
heated, not the whole store, saving on standing losses.

Using a heat bank immersions may be fitted in the different temperature
sections. So, if there is a boiler outage you can run the whole system,
heating and DHW off electricity. You can't do that with a boiler

connected
via a low loss heater.


I forgot to mention. Insert two low loss headers would not cure this
problem. A priority system would need to be in place favouring the rads.
The problem is that the headers do not contain enough mass. In a heat bank
the top rad section could re-heated rapidly and left for while for the rads
to extract the heat. One up to temp it reverts to UFH temps and heat the
lower section. So it would switch from UFH to rads with long intervals
between. This cannot be done with a small mass header. In effect a heat
bank is a very large header

Towel rails: These can be teed in before the diverter valve at the

boiler,
between valve and pump and direct to the return. They will then work in
summer, but only when the cylinder or heat bank is being re-heated, which

is
fine for summer use. If you take a shower and the boiler kicks in the
re-heat you will find the towels are hot on the rails.

Accumulator: If they will not sell unless they supply the unvented

cylinder
(they would sell one separately to me), keep a tank in the loft and have a
booster pump serving a heat bank. This is a cheaper an simpler option too.
The tank does not need to be in the loft. It can be anywhere as it is
pumped.

It would be interesting to see what the Yanks say. They don't do thermal
stores in a big way there and thinking tends to be 1950ish, so only regard
what they say as interest only.

Simpler Alternative:

1. Low Temp Circuit: One dedicated condensing boiler serving the UFH only
on a weather compensator. Simple, separate and sorted.

2. High temp circuit. Another boiler using a 3-way diverter valve

serving
DHW and rads. You may want a weather compensator switching the boikler to
give the ideal temp for the rads. When DHW is called the boiler runs up

to
max temp. This is similar to normal domestic setup.

3. A controller staging in the UFH and rads to give precise control of

room
temps. UFH 1st stage.

4. Backup: Now you have heating backup if one boiler drops out.
Electrical backup for DHW.

5. Cold water storage tank instead of an accumulator with a booster pump.
Tank can be fitted anywhere.

6. The cylinder can be:

a) An unvented version,

b) A DHW only heat bank, such the DPS Pandora, which does requires an
overflow so can be fitted anywhere in the house.

You will find that two condensing boilers can be had for less than the

price
of the Viessmann, and lots of change too.





  #14   Report Post  
John Aston
 
Posts: n/a
Default


IMM wrote in message ...

"John Aston" wrote in message
.. .

Thanks for your help to date. I've distilled the advice from various

threads
in this newsgroup to come up with a possible heating design for my

house.

The drawing HD01 at http://tinyurl.com/3zv2g shows the proposed

hydraulic
design for a large domestic heating system. The boiler and hot water
cylinder is on the left hand side of the drawing, space heating is on

the
right. (You might need to rotate the view so that the drawing is in
landscape orientation in your browser)


Aiden has highlighted some points, so I will not go over them. Some
observations and Qs:

Firstly, what drawing package did you use, Visio?


CorelDraw 6. Not a great program but I'm used to it.

The boiler appears to be a Veissmann with an in-built outside weather
compensator with the temp sensor in the low loss header. If the

compensator
slope is set to the UFH, it will not be suitable for the rads. You would
require the low loss header to be on the minimum temp that the rads take,
which means a higher temperature for the boiler to operate on making it
less efficient. If you set the compensator slope for the higher temp rads,
each the UFH zone will control itself on its own mixer controls, set to
maximum of 55C.


The compensator slope is set for the rads. The UFH is on all the time with a
flow temp of 55°C maximum, modulated down by the thermostatic mixing valve
on each manifold. The radiator temperature is determined by the outside
temperature.

You could use a dual temp boiler as the Eco-Hometec, or a simple boiler
maintaining a hot low loss header at a high temp. This is what is done

with
non-compensating boilers where the return temp "has" to be high. So, as

you
have it the rads will not go about 55C.


So I will avoid the non-compensating boiler and consider a boiler where the
flow temperature is modulated between 50°C and 70°C, say (this can be
adjusted). Therefore, the radiator flow temperature is between 50°C and
70°C. The thermostatic mixers keep the water through the UFH at 55°C or
less.

snip - understood


Do you still intend to have two stage heating? UFH with rads boosting?
Yiou have 5 UFH ziones. Where will the rads fit in relating to these

zones?


Yes. UFH as the primary heat source, with the rads on when it's cold. The
colder it gets, the warmer the flow through the rads.

There are two UFH manifolds (one for the ground floor, one for first floor +
attic). The rads are in every room. When it's reasonably warm outside, only
the UFH is on. When it gets cold, the rads come on. As it gets colder still,
the temperature in the rads starts to increase.

Here are two situations to demonstrate the weather compensation for my house
at 20°C inside:

When the temperature outside is -3°C, the boiler temperature is 70°C, the
mean water-to-air temperature in the radiators is (almost) 40°C and the
water into the UFH manifold is 55°C.
Under these conditions, a heat loss of 31kW from the house of is met by the
UFH output of 17kW plus the combined radiator output of 14kW.

When the temperature outside rises to +3°C, the boiler temperature falls to
55°C, the mean water-to-air temperature in the radiators is (almost) 25°C
and the water into the UFH manifold is 55°C.
Under these conditions, a heat loss of 24kW from the house is met by the UFH
output of 17kW plus the combined radiator output of 7kW. (I derated the rads
by 50% for a 15° fall in mean water-to-air temperature. I hope that's
suitably conservative.)

This means that the temperature of the water flowing into the radiator is
equal to to the temperature of the water flowing into the UFH when it's
above 3°C outside. I'm hoping, therefore, that most of the time I won't have
two different temperatures serving the two types of heat sources.

Back to having differing temps for rads and UFH. As it is, efficiency is
compromised by the high temp rad circuits. You have an efficient expensive
boiler not performing to maximum potential. Look at the low loss header

on
the diagram. Replace this with a heat bank/thermal store. Off the bottom
UFH section of the thermal store have the UFH circuits. Off the high temp
top section have the rads and DHW. You may want to have three sections:

top
DHW, middle rads, bottom UFH. Then you have all circuits coming into a
neutral point, the heat bank.

Now you have greater control of temperatures, dividing and ruling, which
means the boiler will not be running at too high a temperature to suit

only
the rads compromising efficiency. An outside weather compensator can be

on
the UFH section to keep this part of the store at the ideal high efficient
low temperature and prevent boiler cycling. You may want a compensator on

a
heat bank mid section serving the rads (UFH & rads have different slopes).

Using a heat bank, a far cheaper and simpler boiler may be used.

Having three sections means that in summer, only the DHW top section is
heated, not the whole store, saving on standing losses.

Using a heat bank immersions may be fitted in the different temperature
sections. So, if there is a boiler outage you can run the whole system,
heating and DHW off electricity. You can't do that with a boiler

connected
via a low loss heater.

Towel rails: These can be teed in before the diverter valve at the

boiler,
between valve and pump and direct to the return. They will then work in
summer, but only when the cylinder or heat bank is being re-heated, which

is
fine for summer use. If you take a shower and the boiler kicks in the
re-heat you will find the towels are hot on the rails.


I understand. I guess this assumes that the header has been replaced by the
heat store. (The header would be a very low resistance compared to the towel
rails.)

Accumulator: If they will not sell unless they supply the unvented

cylinder
(they would sell one separately to me), keep a tank in the loft and have a
booster pump serving a heat bank. This is a cheaper an simpler option too.
The tank does not need to be in the loft. It can be anywhere as it is
pumped.

It would be interesting to see what the Yanks say. They don't do thermal
stores in a big way there and thinking tends to be 1950ish, so only regard
what they say as interest only.

Simpler Alternative:

1. Low Temp Circuit: One dedicated condensing boiler serving the UFH only
on a weather compensator. Simple, separate and sorted.

2. High temp circuit. Another boiler using a 3-way diverter valve

serving
DHW and rads. You may want a weather compensator switching the boikler to
give the ideal temp for the rads. When DHW is called the boiler runs up

to
max temp. This is similar to normal domestic setup.

3. A controller staging in the UFH and rads to give precise control of

room
temps. UFH 1st stage.

4. Backup: Now you have heating backup if one boiler drops out.
Electrical backup for DHW.

5. Cold water storage tank instead of an accumulator with a booster pump.
Tank can be fitted anywhere.

6. The cylinder can be:

a) An unvented version,

b) A DHW only heat bank, such the DPS Pandora, which does requires an
overflow so can be fitted anywhere in the house.

You will find that two condensing boilers can be had for less than the

price
of the Viessmann, and lots of change too.



Thank you for taking the time to compose this reply, I appreciate your
thoughts. I believe that I understand the principle of the heat store and
the principle of a modulating boiler. They both have their advantages. I'll
get some prices together and put my best foot forward.


  #15   Report Post  
Aidan
 
Posts: n/a
Default

"John Aston" wrote in message ...


OK. I was worried about a drop in the pressure/flow rate. My incoming

supply
is only 2.8 bar static and 30lpm.

It would probably be OK to just relocate the DCV shown. I think the
Water Regulations require a DCV on a softener inlet. The mains
pressure varies inversely with demand in the neighbourhood during the
day, so you'd work on the minimum. The flow rate achieved at the
minimum pressure should indicate whether you might need the
accumulator.

I never knew its effect on copper pipes! I'm surprised they don't

mention it


It's not something the manufacturers publicise and I don't have any
definite information. My understanding is that it's something that can
happen, but that the softener isn't always the guilty party. Erosion
and bad pipe-fitting have some role. My understanding is that water
softened & blended to about 40ppm hardness is fine for all practical
purposes and doesn't create the corrosion problems. Softened water can
be unpleasant stuff in the wrong place. I think the dissolved calcium
salts are mostly changed into sodium carbonate (washing soda?).

I've no experience of Kinetico.

The last test kit I used was made by Hach, supplied by a company
called CamLab. It was a titration test kit (colour change). I've found
dip strips can be misleading in some hands (RTFM again).

I guess it's set at 3.5 bar to comply with regulations. It might be easier to leave out the downstream PRV. The mains static pressure is only 2.8 bar anyway.


I think your original detail & IMM were right (Ow, that hurt!) & I was
wrong. The upstream PRV would be set to limit the pressure to the
design rating of the accumulator.

I once had a discussion with an HSE inspector who expected to see
every PRV accompanied by a correctly-sized safety/pressure relief
valve to prevent the equipment being over-pressurized in the (quite
likely) event of a PRV failure. We were talking about compressed air,
but his point is still valid here.

I did think about this but

(a) The cylinder is less than 8m pipe length from the boiler

This seems to be a compromise between the conflicting requirements of
supplying the cylinder with sufficiently hot water (to get the stored
DHW above 60degC), keeping the boiler return temperature low and
avoiding the need for lots of mixing valves. It's outside my
experience, so I'll shut up.

Yes, you're right. The header is a pre-fabricated assembly.


You could fabricate one, it's just pipe & fittings.


I'm hoping that these come as part of the manifold from the UFH

suppliers

Only if you specify them.
The flow-rate indicators are an optional extra. They usually become
unreadable after a few years, so are only useful for initial
balancing. You need to make a record of the settings and keep it in a
safe place.

Also, you can see on the diagram that I've written MAX. DISTANCE? I can't get any definitive answers


There is no maximum, so long as the pump(s) can handle the resistance
at the flow rate.

The UFH heating circuits have their own individual themostats.


Yes, but I was querying why you need a motorized control valve
adjacent to the UFH manifolds' mixing valves. If the pipe stat
temperature was exceeded, you could stop the pump and/or set the
mixing valve to 0%. Are the mixing valves thermostatic or electric?


The heat losses would be 31kW. I'm hoping that the additional 7kW will give

me some headroom plus a bit for the domestic hot water.

An additional 7kW should be lots, check the cylinder manufacturer's
spec. You won't need additional capacity if the HWS has priority, as
IMM said. I don't like the diverting idea, but I see the need for it.

A couple of other points;

The DOCs on the heating zones return pipes should be upstream of the
IVs. They should drain the zone when the IVs are shut, but will drain
the whole system as shown.

You have to ensure that the primary flow through the low loss header
is greater than the secondary flow at all times. If the secondary flow
is greater, then some of the secondary return flows back up the header
and you then get a reduction in the secondary flow temperature.

The drain pipe from the tundish on the cylinder has some rules to
determine the pipe size, depending on the pipe length and number of
elbows. It's usually not a problem, but needs to be considered if the
proposed cylinder position is a long way from the final "safe &
visible" outlet outside. Otherwise, you can end up with a huge drain
pipe or it can be impractical. The cylinder can't be in a basement.

Thanks, Aidan.

A pleasure.


  #16   Report Post  
IMM
 
Posts: n/a
Default


"Aidan" wrote in message
om...
"John Aston" wrote in message

...


OK. I was worried about a drop in the pressure/flow rate. My incoming

supply
is only 2.8 bar static and 30lpm.

It would probably be OK to just relocate the DCV shown. I think the
Water Regulations require a DCV on a softener inlet. The mains
pressure varies inversely with demand in the neighbourhood during the
day, so you'd work on the minimum. The flow rate achieved at the
minimum pressure should indicate whether you might need the
accumulator.

I never knew its effect on copper pipes! I'm surprised they don't

mention it


It's not something the manufacturers publicise and I don't have any
definite information. My understanding is that it's something that can
happen, but that the softener isn't always the guilty party. Erosion
and bad pipe-fitting have some role. My understanding is that water
softened & blended to about 40ppm hardness is fine for all practical
purposes and doesn't create the corrosion problems. Softened water can
be unpleasant stuff in the wrong place. I think the dissolved calcium
salts are mostly changed into sodium carbonate (washing soda?).

I've no experience of Kinetico.

The last test kit I used was made by Hach, supplied by a company
called CamLab. It was a titration test kit (colour change). I've found
dip strips can be misleading in some hands (RTFM again).

I guess it's set at 3.5 bar to comply with regulations. It might be

easier to leave out the downstream PRV. The mains static pressure is only
2.8 bar anyway.

I think your original detail & IMM were right (Ow, that hurt!) & I was
wrong. The upstream PRV would be set to limit the pressure to the
design rating of the accumulator.

I once had a discussion with an HSE inspector who expected to see
every PRV accompanied by a correctly-sized safety/pressure relief
valve to prevent the equipment being over-pressurized in the (quite
likely) event of a PRV failure. We were talking about compressed air,
but his point is still valid here.

I did think about this but

(a) The cylinder is less than 8m pipe length from the boiler

This seems to be a compromise between the conflicting requirements of
supplying the cylinder with sufficiently hot water (to get the stored
DHW above 60degC), keeping the boiler return temperature low and
avoiding the need for lots of mixing valves. It's outside my
experience, so I'll shut up.

Yes, you're right. The header is a pre-fabricated assembly.


You could fabricate one, it's just pipe & fittings.


I'm hoping that these come as part of the manifold from the UFH

suppliers

Only if you specify them.
The flow-rate indicators are an optional extra. They usually become
unreadable after a few years, so are only useful for initial
balancing. You need to make a record of the settings and keep it in a
safe place.

Also, you can see on the diagram that I've written MAX. DISTANCE? I

can't get any definitive answers

There is no maximum, so long as the pump(s) can handle the resistance
at the flow rate.

The UFH heating circuits have their own individual themostats.


Yes, but I was querying why you need a motorized control valve
adjacent to the UFH manifolds' mixing valves. If the pipe stat
temperature was exceeded, you could stop the pump and/or set the
mixing valve to 0%. Are the mixing valves thermostatic or electric?


The heat losses would be 31kW. I'm hoping that the additional 7kW will

give
me some headroom plus a bit for the domestic hot water.

An additional 7kW should be lots, check the cylinder manufacturer's
spec. You won't need additional capacity if the HWS has priority, as
IMM said. I don't like the diverting idea, but I see the need for it.

A couple of other points;

The DOCs on the heating zones return pipes should be upstream of the
IVs. They should drain the zone when the IVs are shut, but will drain
the whole system as shown.

You have to ensure that the primary
flow through the low loss header
is greater than the secondary flow
at all times.


It should be the reverse, even Viessmann say that. The idea is that the
secondary circuits will take all of the flow from the header with little
going back to the boiler fom the boiler flow (short circuit). The idea is
that all the hot water coming into the header from the boiler will be sucked
into the secondary circuit. What returns from the header to the boiler
should be cooled water from the secondary circuits.

If the secondary flow
is greater, then some of the secondary
return flows back up the header
and you then get a reduction in the secondary flow temperature.

The drain pipe from the tundish on the cylinder has some rules to
determine the pipe size, depending on the pipe length and number of
elbows. It's usually not a problem, but needs to be considered if the
proposed cylinder position is a long way from the final "safe &
visible" outlet outside. Otherwise, you can end up with a huge drain
pipe or it can be impractical. The cylinder can't be in a basement.

Thanks, Aidan.

A pleasure.



  #17   Report Post  
IMM
 
Posts: n/a
Default


"John Aston" wrote in message
.. .

IMM wrote in message

...

"John Aston" wrote in message
.. .

Thanks for your help to date. I've distilled the advice from various

threads
in this newsgroup to come up with a possible heating design for my

house.

The drawing HD01 at http://tinyurl.com/3zv2g shows the proposed

hydraulic
design for a large domestic heating system. The boiler and hot water
cylinder is on the left hand side of the drawing, space heating is on

the
right. (You might need to rotate the view so that the drawing is in
landscape orientation in your browser)


Aiden has highlighted some points, so I will not go over them. Some
observations and Qs:

Firstly, what drawing package did you use, Visio?


CorelDraw 6. Not a great program but I'm used to it.

The boiler appears to be a Veissmann with an in-built outside weather
compensator with the temp sensor in the low loss header. If the

compensator
slope is set to the UFH, it will not be suitable for the rads. You would
require the low loss header to be on the minimum temp that the rads

take,
which means a higher temperature for the boiler to operate on making it
less efficient. If you set the compensator slope for the higher temp

rads,
each the UFH zone will control itself on its own mixer controls, set to
maximum of 55C.


The compensator slope is set for the rads.
The UFH is on all the time with a
flow temp of 55°C maximum, modulated down
by the thermostatic mixing valve
on each manifold. The radiator temperature
is determined by the outside
temperature.


It is as I suspected not taking full advantage of the boilers efficiency.
The UFH is running all the time and the rads occasionally, yet the boiler is
set to for maximum efficiency on the high temp rads.

You could use a dual temp boiler as the
Eco-Hometec, or a simple boiler
maintaining a hot low loss header at
a high temp. This is what is done
with non-compensating boilers where
the return temp "has" to be high. So, as
you have it the rads will not go about 55C.


So I will avoid the non-compensating boiler
and consider a boiler where the
flow temperature is modulated between
50°C and 70°C, say (this can be
adjusted). Therefore, the radiator flow temperature
is between 50°C and 70°C. The thermostatic
mixers keep the water through the UFH at 55°C or
less.


Typo on my part. Should have been non-condensing. A weather compensator can
be on the rads circuit too. A weather compensator can be an external
controller rather than an internal one (integrated with the boiler).
Danfoss Randall make one for around £160.

snip - understood


Do you still intend to have two stage heating?
UFH with rads boosting?
You have 5 UFH zones. Where will the
rads fit in relating to these zones?


Yes. UFH as the primary heat source,
with the rads on when it's cold. The
colder it gets, the warmer the flow
through the rads.


Weather compensation.

There are two UFH manifolds (one for
the ground floor, one for first floor +
attic). The rads are in every room. When
it's reasonably warm outside, only
the UFH is on. When it gets cold, the rads
come on. As it gets colder still,
the temperature in the rads starts to increase.

Here are two situations to demonstrate the
weather compensation for my house
at 20°C inside:

When the temperature outside is -3°C, the boiler temperature is 70°C, the
mean water-to-air temperature in the radiators is (almost) 40°C and the
water into the UFH manifold is 55°C.
Under these conditions, a heat loss of 31kW from the house of is met by

the
UFH output of 17kW plus the combined radiator output of 14kW.

When the temperature outside rises to +3°C, the boiler temperature falls

to
55°C, the mean water-to-air temperature in the radiators is (almost) 25°C
and the water into the UFH manifold is 55°C.
Under these conditions, a heat loss of 24kW
from the house is met by the UFH output of 17kW plus the combined radiator

output of 7kW. (I derated the rads
by 50% for a 15° fall in mean water-to-air temperature. I hope that's
suitably conservative.)

This means that the temperature of the water flowing into the radiator is
equal to to the temperature of the water flowing into the UFH when it's
above 3°C outside. I'm hoping, therefore, that most of the time I won't

have
two different temperatures serving the two types of heat sources.


Having two different temperatures for rads and UFH is the way.

Back to having differing temps for rads and UFH. As it is, efficiency

is
compromised by the high temp rad circuits. You have an efficient

expensive
boiler not performing to maximum potential. Look at the low loss header

on
the diagram. Replace this with a heat bank/thermal store. Off the

bottom
UFH section of the thermal store have the UFH circuits. Off the high

temp
top section have the rads and DHW. You may want to have three sections:

top
DHW, middle rads, bottom UFH. Then you have all circuits coming into a
neutral point, the heat bank.

Now you have greater control of temperatures, dividing and ruling, which
means the boiler will not be running at too high a temperature to suit

only
the rads compromising efficiency. An outside weather compensator can be

on
the UFH section to keep this part of the store at the ideal high

efficient
low temperature and prevent boiler cycling. You may want a compensator

on
a
heat bank mid section serving the rads (UFH & rads have different

slopes).

Using a heat bank, a far cheaper and simpler boiler may be used.

Having three sections means that in summer, only the DHW top section is
heated, not the whole store, saving on standing losses.

Using a heat bank immersions may be fitted in the different temperature
sections. So, if there is a boiler outage you can run the whole system,
heating and DHW off electricity. You can't do that with a boiler

connected
via a low loss heater.

Towel rails: These can be teed in before the diverter valve at the

boiler,
between valve and pump and direct to the return. They will then work in
summer, but only when the cylinder or heat bank is being re-heated,

which
is
fine for summer use. If you take a shower and the boiler kicks in the
re-heat you will find the towels are hot on the rails.


I understand. I guess this assumes that the header
has been replaced by the heat store.


Yes. The store also serves the DHW too. So it replaces the header and
serves DHW, UFH and rads and prevents boiler cycling.

(The header would be a very low resistance
compared to the towel rails.)


That is so.

Accumulator: If they will not sell unless they supply the unvented

cylinder
(they would sell one separately to me), keep a tank in the loft and have

a
booster pump serving a heat bank. This is a cheaper an simpler option

too.
The tank does not need to be in the loft. It can be anywhere as it is
pumped.

It would be interesting to see what the Yanks say. They don't do

thermal
stores in a big way there and thinking tends to be 1950ish, so only

regard
what they say as interest only.

Simpler Alternative:

1. Low Temp Circuit: One dedicated condensing boiler serving the UFH

only
on a weather compensator. Simple, separate and sorted.

2. High temp circuit. Another boiler using a 3-way diverter valve

serving
DHW and rads. You may want a weather compensator switching the boikler

to
give the ideal temp for the rads. When DHW is called the boiler runs up

to
max temp. This is similar to normal domestic setup.

3. A controller staging in the UFH and rads to give precise control of

room
temps. UFH 1st stage.

4. Backup: Now you have heating backup if one boiler drops out.
Electrical backup for DHW.

5. Cold water storage tank instead of an accumulator with a booster

pump.
Tank can be fitted anywhere.

6. The cylinder can be:

a) An unvented version,

b) A DHW only heat bank, such the DPS Pandora, which does requires an
overflow so can be fitted anywhere in the house.

You will find that two condensing boilers can be had for less than the

price
of the Viessmann, and lots of change too.


Thank you for taking the time to compose this reply, I appreciate your
thoughts. I believe that I understand the principle of the heat store and
the principle of a modulating boiler. They both have their advantages.

I'll
get some prices together and put my best foot forward.


In your case with having three differing functions of different temperatures
a heat bank is the ideal way to supply those temperatures promoting maximum
efficiency from the boiler.

The most efficient, and easiest, is having two boilers as described above.




  #18   Report Post  
Andy Hall
 
Posts: n/a
Default

On Wed, 17 Nov 2004 00:52:49 -0000, "IMM" wrote:



Typo on my part. Should have been non-condensing. A weather compensator can
be on the rads circuit too. A weather compensator can be an external
controller rather than an internal one (integrated with the boiler).
Danfoss Randall make one for around £160.


This is a poor way to do it because these controllers work by turning
the boiler on and off for variable periods.





Yes. The store also serves the DHW too. So it replaces the header and
serves DHW, UFH and rads and prevents boiler cycling.


The cycling issue is a corner case and is irrelevant for the types of
boiler under consideration.







--

..andy

To email, substitute .nospam with .gl
  #19   Report Post  
IMM
 
Posts: n/a
Default


"Andy Hall" wrote in message
...
On Wed, 17 Nov 2004 00:52:49 -0000, "IMM" wrote:



Typo on my part. Should have been
non-condensing. A weather compensator can
be on the rads circuit too. A weather compensator
can be an external controller rather than an
internal one (integrated with the boiler).
Danfoss Randall make one for around £160.


This is a poor way to do it because these controllers work by turning
the boiler on and off for variable periods.


It is not a poor way of doing it. Anti-cycle control is incorporated in most
boilers and the compensator. I have had one switch a boiler for eons and
there is no excessive cycling at all. Coupled to a large mass of water,
like a heat bank, and cycling will be minimal to the point it is not an
issue.

If the UFH heating is being run directly from a boiler dedicated to that
function then there are boilers around a lot cheaper with integral weather
compensation as an extra, that will modulate down on the compensator
control.

Yes. The store also serves the DHW too.
So it replaces the header and
serves DHW, UFH and rads and prevents
boiler cycling.


The cycling issue is a corner case
and is irrelevant for the types of
boiler under consideration.


Once using a thermal store this expensive boiler is then not an issue. A
cheaper simpler boiler can be used, that is one of the selling points of
thermal stores/heat banks.

In this case with three functions: DHW, UFH and rads, all operating on
different temperatures, a heat bank/thermal store is by far the best
solution, maximising boioer efficiency.




  #20   Report Post  
Andy Hall
 
Posts: n/a
Default

On Wed, 17 Nov 2004 09:07:09 -0000, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Wed, 17 Nov 2004 00:52:49 -0000, "IMM" wrote:



Typo on my part. Should have been
non-condensing. A weather compensator can
be on the rads circuit too. A weather compensator
can be an external controller rather than an
internal one (integrated with the boiler).
Danfoss Randall make one for around £160.


This is a poor way to do it because these controllers work by turning
the boiler on and off for variable periods.


It is not a poor way of doing it. Anti-cycle control is incorporated in most
boilers and the compensator. I have had one switch a boiler for eons and
there is no excessive cycling at all. Coupled to a large mass of water,
like a heat bank, and cycling will be minimal to the point it is not an
issue.


Cycling a boiler at full output is a very different issue than doing
so at 3kW in terms of efficiency.

Since the discussion is based around a modulating boiler, this type of
controller is irrelevant.



If the UFH heating is being run directly from a boiler dedicated to that
function then there are boilers around a lot cheaper with integral weather
compensation as an extra, that will modulate down on the compensator
control.

Yes. The store also serves the DHW too.
So it replaces the header and
serves DHW, UFH and rads and prevents
boiler cycling.


The cycling issue is a corner case
and is irrelevant for the types of
boiler under consideration.


Once using a thermal store this expensive boiler is then not an issue. A
cheaper simpler boiler can be used, that is one of the selling points of
thermal stores/heat banks.


It is if you're DPS and trying to flog heatbanks.

However, if you are the purchaser, the equation may be quite
different,.


In this case with three functions: DHW, UFH and rads, all operating on
different temperatures, a heat bank/thermal store is by far the best
solution, maximising boioer efficiency.


You haven;t explained how all of this can be done with the operating
parameters of the boiler type under discussion.

I think that you are simply bunching together all of the claimed
advantages and assuming that they all can happen concurrently. I
don't believe that that is possible.


--

..andy

To email, substitute .nospam with .gl


  #21   Report Post  
John Aston
 
Posts: n/a
Default


"IMM" wrote in message
...

"John Aston" wrote in message
.. .


Thank you for taking the time to compose this reply, I appreciate your
thoughts. I believe that I understand the principle of the heat store

and
the principle of a modulating boiler. They both have their advantages.
I'll get some prices together and put my best foot forward.


In your case with having three differing functions of different

temperatures
a heat bank is the ideal way to supply those temperatures promoting

maximum
efficiency from the boiler.

The most efficient, and easiest, is having two boilers as described above.


IMM, leaving my particular case to one side, may I ask in what application
would you recommend the use of a weather-compensated modulating boiler?


  #22   Report Post  
IMM
 
Posts: n/a
Default

"John Aston" wrote in message
...

In your case with having three
differing functions of different
temperatures a heat bank is the
ideal way to supply those temperatures
promoting maximum
efficiency from the boiler.

The most efficient, and easiest,
is having two boilers as described above.


IMM, leaving my particular case to one side,
may I ask in what application would you
recommend the use of a weather-compensated
modulating boiler?


Firstly, having a dedicated boiler for distinct functions is the ideal
method: DHW, UFH, rads. Separate dedicated functions easy to control and
design. That was the way in ye olden times. But in ye olden days boilers
were expensive and very large, so quickly they found ways of joining up all
the various circuits: DHW, rads, fan coil unit circuits etc. They devised
methods using headers, buffers (thermal store) etc. All this was a
compromise to tap into one source of heat, the boiler. It worked well
because the boilers had to operate at high temperature because they were
non-condensing. High temperatures water was on tap and the varios circuits
tapped off it blending it down when necessary for the various circuit
functions.

In commercial applications they could then have two sequenced boilers,
bringing in both or just one, or none, depending on heat demand, and a spare
boiler if one is down. All was fine and dandy and things went along like
that for decades. These sort of systems are still in the mindset of many
designers today, designing the total system to the highest temp required in
a sub-system.

Then condensing boilers came along offering high efficinencies the lower the
return temp. This required a re-think. With a simple two function system
of say: DHW and UFH you could have the boiler on a weather compensator
serving the UFH to the lowest temps for high efficient operation. If DHW is
called, a 3-way diverter sends all the boilers heat to the cylinder (must be
quick recovery) while ramping up the boiler temp to maximum for the high
temp DHW requies and rapid DHW re-heat. When more than one function is
thrown in, with all three, or more, requiring different operating temps, as
in the rads of your system, matters become a little complicated when the aim
is to keep the boiler running at the lowest return temperature for maximum
efficiency.

Also, boilers became smaller and smaller and cheaper and cheaper. This then
made the dedicated function boiler a cost effective reality. To implement a
condensing boiler system to maxiumum efficiency, running it at the lowest
temps for most of the time, it becomes more expensive in ancilliry equipment
and controls, and complicated, as you have seen in attempting to get a
solution. The best solution was thermal store/heat bank with dedicated
sections, or zones, for the various functions (DHW, UFH, rads) down the
store with these sections providing exactly the the right temperature for
the functions. The boiler only heating one of these sections at a time to
the lowest temperature for that function - ideal, and sorted.

Back to your question. "what application would you recommend the use of a
weather-compensated modulating boiler?"

If you have one function, say just rads or UFH then it is ideal. It is also
ideal for two functions, but a priorty system is required, with the highest
temp having priority with boiler cycling eliminated. A thermal store can
supply a buffer of water to eliminate this, as you don't want the system
cycling from one function (UFH) to the other (rads or UFH) every couple of
minutes.

The answer:

1. One dedicated function (like rads or UFH)

2. Two functions like UFH and DHW (only if the system is designed properly
to a priority system).

To go further.........

As I have said, in your case it is worth costing up:

1. Low Temp Circuit: One dedicated condensing boiler serving the UFH only
on a weather compensator. Simple, separate and sorted.

A number of makers supply integrated weather compensated boilers, as an
extra. Viessmann, MAN, etc, are very expesnive and will probably have far
more control functionallity than what you need. They are very good and the
RRs of boilers, with price to match. Very good boilers are available from
reputable makers much cheaper.

2. High temp circuit. Another boiler using a 3-way diverter valve serving
DHW and rads with DHW priority. You may want a weather compensator
maintaining boiler to the lowest temp the rads require. When DHW is called
the boiler runs up to max temp. This is similar to normal domestic setup.

3. A controller staging in the UFH and rads to give precise seamless
control of room temps. UFH 1st stage, rads 2nd.

4. Backup: Now you have heating backup if one boiler drops out. Electrical
backup for DHW in the cylidner or heat bank cylinder.

6. The cylinder can be:
a) An unvented version,

b) A DHW only heat bank, such the DPS Pandora, which doe not require an
overflow so can be fitted anywhere in the house and will take high pressures
way above 3.5 bar.


You will find that two condensing boilers can be had for less than the price
of the Viessmann, and lots of change too.



  #23   Report Post  
IMM
 
Posts: n/a
Default


"Andy Hall" wrote in message
...
On Wed, 17 Nov 2004 09:07:09 -0000, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Wed, 17 Nov 2004 00:52:49 -0000, "IMM" wrote:



Typo on my part. Should have been
non-condensing. A weather compensator can
be on the rads circuit too. A weather compensator
can be an external controller rather than an
internal one (integrated with the boiler).
Danfoss Randall make one for around £160.

This is a poor way to do it because these controllers work by turning
the boiler on and off for variable periods.


It is not a poor way of doing it. Anti-cycle control is incorporated in

most
boilers and the compensator. I have had one switch a boiler for eons and
there is no excessive cycling at all. Coupled to a large mass of water,
like a heat bank, and cycling will be minimal to the point it is not an
issue.


Cycling a boiler at full output is a
very different issue than doing
so at 3kW in terms of efficiency.


It isn't. As I said cycling is not a issue as control and buffer measures
can be incorporated.

Since the discussion is based around
a modulating boiler, this type of
controller is irrelevant.


It isn't. To you it is as you are obsessed with your boiler. It is about
getting the most cost effective solution to a run a system to maximum
efficiency.

If the UFH heating is being run directly from a boiler dedicated to that
function then there are boilers around a lot cheaper with integral

weather
compensation as an extra, that will modulate down on the compensator
control.

Yes. The store also serves the DHW too.
So it replaces the header and
serves DHW, UFH and rads and prevents
boiler cycling.

The cycling issue is a corner case
and is irrelevant for the types of
boiler under consideration.


Once using a thermal store this
expensive boiler is then not an issue. A
cheaper simpler boiler can be used, that
is one of the selling points of
thermal stores/heat banks.


It is if you're DPS and trying
to flog heatbanks.


It is an issue for everyone as we all have boiler and people wanting most
efficient and simplest at the least cost. You know like all that free
market stuff you were on about, which in your tiny mind does not apply to
boilers or land.

However, if you are the purchaser, the equation may be quite
different,.

In this case with three functions: DHW, UFH and rads, all operating on
different temperatures, a heat bank/thermal store is by far the best
solution, maximising boiler efficiency.


You haven;t explained how all of
this can be done with the operating
parameters of the boiler type under
discussion.


What is under discussion is a system, not a single bloody boiler.

I think that you are simply bunching together all of the claimed
advantages and assuming that they all can happen concurrently. I
don't believe that that is possible.


See my recent post on this.




  #24   Report Post  
Andy Hall
 
Posts: n/a
Default

On Wed, 17 Nov 2004 12:55:55 -0000, "IMM" wrote:


"Andy Hall" wrote in message



Cycling a boiler at full output is a
very different issue than doing
so at 3kW in terms of efficiency.


It isn't. As I said cycling is not a issue as control and buffer measures
can be incorporated.


With the boiler providing the control and the load providing the
buffer.

Are you claiming that the impact of a boiler cycling between full
power (e.g. 40kW and nothing) is the same as it cycling, only at a
certain small range between 3kW and nothing?



Since the discussion is based around
a modulating boiler, this type of
controller is irrelevant.


It isn't. To you it is as you are obsessed with your boiler. It is about
getting the most cost effective solution to a run a system to maximum
efficiency.


I'm not obsessed with anything. Efficiency comes from maintaining
the lowest possible return temperature and matching generation to load
to minimise cycling.


iler under consideration.

Once using a thermal store this
expensive boiler is then not an issue. A
cheaper simpler boiler can be used, that
is one of the selling points of
thermal stores/heat banks.


It is if you're DPS and trying
to flog heatbanks.


It is an issue for everyone as we all have boiler and people wanting most
efficient and simplest at the least cost.


We are hardly discussing the simplest type of system or the average
requirement here. Other factors such as reliability and
performance also enter the equation.

You know like all that free
market stuff you were on about, which in your tiny mind does not apply to
boilers or land.


What on earth does land have to do with anything here? Don't bother
to answer that.



However, if you are the purchaser, the equation may be quite
different,.

In this case with three functions: DHW, UFH and rads, all operating on
different temperatures, a heat bank/thermal store is by far the best
solution, maximising boiler efficiency.


You haven;t explained how all of
this can be done with the operating
parameters of the boiler type under
discussion.


What is under discussion is a system, not a single bloody boiler.


Of course.



I think that you are simply bunching together all of the claimed
advantages and assuming that they all can happen concurrently. I
don't believe that that is possible.


See my recent post on this.


You mean the collection of cut and paste from the DPS and other web
sites? If you can't answer the question, then I understand why,
don't worry about it.





--

..andy

To email, substitute .nospam with .gl
  #25   Report Post  
IMM
 
Posts: n/a
Default


"Andy Hall" wrote in message
...
On Wed, 17 Nov 2004 12:55:55 -0000, "IMM" wrote:


"Andy Hall" wrote in message



Cycling a boiler at full output is a
very different issue than doing
so at 3kW in terms of efficiency.


It isn't. As I said cycling is not a issue as control and buffer

measures
can be incorporated.


With the boiler


snip

You have a lot to learn.





  #26   Report Post  
John Aston
 
Posts: n/a
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Aidan wrote in message
om...
"John Aston" wrote in message

...

snip comments - thanks for these

The UFH heating circuits have their own individual themostats.


Yes, but I was querying why you need a motorized control valve
adjacent to the UFH manifolds' mixing valves. If the pipe stat
temperature was exceeded, you could stop the pump and/or set the
mixing valve to 0%. Are the mixing valves thermostatic or electric?


I put the valve in because the UFH supplier has one shown on his manifold
drawing. You're right about simply stopping the pump though...
The mixing valve is thermostatic, so flow control should be via the pump.

A couple of other points;

snip


Thanks, Aidan. For the benefit of The Wall, I've posted a revised drawing at
http://tinyurl.com/5lx84 (although it has one DCV too many).


  #27   Report Post  
IMM
 
Posts: n/a
Default


"John Aston" wrote in message
.. .

Aidan wrote in message
om...
"John Aston" wrote in message

...

snip comments - thanks for these

The UFH heating circuits have their own individual themostats.


Yes, but I was querying why you need a motorized control valve
adjacent to the UFH manifolds' mixing valves. If the pipe stat
temperature was exceeded, you could stop the pump and/or set the
mixing valve to 0%. Are the mixing valves thermostatic or electric?


I put the valve in because the UFH supplier has one shown on his manifold
drawing. You're right about simply stopping the pump though...
The mixing valve is thermostatic, so flow control should be via the pump.

A couple of other points;

snip


Thanks, Aidan. For the benefit of The Wall, I've posted a revised drawing

at
http://tinyurl.com/5lx84 (although it has one DCV too many).


I can't see much which has been revised. Still lots to do to get it right.




  #28   Report Post  
John Aston
 
Posts: n/a
Default

IMM wrote in message ...


It would be interesting to see what the Yanks say. They don't do thermal
stores in a big way there and thinking tends to be 1950ish, so only regard
what they say as interest only.


It's posted at http://tinyurl.com/6ff4u



  #29   Report Post  
John Aston
 
Posts: n/a
Default


"IMM" wrote in message
...

"John Aston" wrote in message
.. .

Aidan wrote in message
om...

snip


Thanks, Aidan. For the benefit of The Wall, I've posted a revised

drawing
at
http://tinyurl.com/5lx84 (although it has one DCV too many).


I can't see much which has been revised. Still lots to do to get it

right.

This revised drawing reflected Aidan's comments. Whether my design is
feasible is still open to discussion.


  #30   Report Post  
John Aston
 
Posts: n/a
Default

"IMM" wrote in message ...
"John Aston" wrote in message
.. .

snip

Simpler Alternative:

1. Low Temp Circuit: One dedicated condensing boiler serving the UFH only
on a weather compensator. Simple, separate and sorted.

2. High temp circuit. Another boiler using a 3-way diverter valve serving
DHW and rads. You may want a weather compensator switching the boikler to
give the ideal temp for the rads.


Do you mean that the weather compensator changes the boiler setpoint
according to the outdoor temperature? If so, which (good quality)
boilers have this feature, please?

When DHW is called the boiler runs up to
max temp. This is similar to normal domestic setup.

3. A controller staging in the UFH and rads to give precise control of room
temps. UFH 1st stage.

4. Backup: Now you have heating backup if one boiler drops out.
Electrical backup for DHW.

5. Cold water storage tank instead of an accumulator with a booster pump.
Tank can be fitted anywhere.

6. The cylinder can be:

a) An unvented version,

b) A DHW only heat bank, such the DPS Pandora, which does requires an
overflow so can be fitted anywhere in the house.

You will find that two condensing boilers can be had for less than the price
of the Viessmann, and lots of change too.


For an inexpensive condensing boiler, if the resistance of the load is
greater than the boiler pump's residual head, can I simply put an
external pump in series with the flow output?


  #31   Report Post  
IMM
 
Posts: n/a
Default



"John Aston" wrote in message
om...

"IMM" wrote in message

...


Simpler Alternative:

1. Low Temp Circuit: One dedicated condensing


boiler serving the UFH only on a weather compensator.


Simple, separate and sorted.

2. High temp circuit. Another boiler using a 3-way


diverter valve serving DHW and rads. You may


want a weather compensator switching the boiler to
give the ideal temp for the rads.


Do you mean that the weather compensator


changes the boiler setpoint according to the


outdoor temperature?




Yes.



If so, which (good quality)
boilers have this feature, please?




The Veissmann you have been looking at. The MAN (Eco-Hometec). Cheaper is
the Ferroli MaXima 35 S which incorporates a weather compensator and geared
for UFH. A quick Google shows this for £625 + VAT, so well priced and a good
boiler too.



http://www.ferroli.co.uk/



A stand alone weather compensator can be bought for around £160, which will
switch in and out a boiler to the dictates of the weather compensator. This
can be used on cheaper good quality boilers: Worcester-Bosch, Glow Worm,
Ideal, etc.



The boilers with integrated weather compensators modulate the burner to
suit.


When DHW is called the boiler runs up to
max temp. This is similar to normal domestic setup.

3. A controller staging in the UFH and rads


to give precise control of room
temps. UFH 1st stage.

4. Backup: Now you have heating


backup if one boiler drops out.
Electrical backup for DHW.

5. Cold water storage tank instead of an


accumulator with a booster pump.
Tank can be fitted anywhere.

6. The cylinder can be:

a) An unvented version,

b) A DHW only heat bank, such the DPS Pandora,


which doesn't requires an
overflow so can be fitted anywhere in the house.

You will find that two condensing boilers can be


had for less than the price
of the Viessmann, and lots of change too.


For an inexpensive condensing boiler,


if the resistance of the load is
greater than the boiler pump's residual head,




Where did you get that from? Cheaper doesn't mean smaller.



can I simply put an
external pump in series with


the flow output?




Yes, but a boiler of around 25kw for your needs will do fine.



Your setup. If a boiler is only doing UFH, then no 3-way valve is required
and the boiler is set to 55C max temp, and the weather compensator raises
and lowers the boiler temp. Totally direct. Now a system boiler has an
integral pump and will switch this off when the burner is switched off
(there may be a run on for overheat). You want the pump on all the time. So
a heating boiler that comes without a pump is probably the best option. The
weather compensator switches the burner and the pump always running.



Some of the expensive boilers that take into account UFH may keep the pump
running.






  #32   Report Post  
John Aston
 
Posts: n/a
Default

Thanks to everyone who contributed heating design ideas.

The design is finalised and I am considering placement of the
components.

I plan to put the 40kW condensing boiler (Keston C40) and cylinder in a
cupboard at one end of the bathroom. At the opposite end of the
bathroom, 4m away, is the adjoining wall with my bedroom.

Is the boiler likely to keep me awake at night if I put it in this
location?

  #33   Report Post  
John Aston
 
Posts: n/a
Default

Thanks to everyone who contributed heating design ideas.

The design is finalised and I am considering placement of the
components.

I plan to put the 40kW condensing boiler (Keston C40) and cylinder in a
cupboard at one end of the bathroom. At the opposite end of the
bathroom, 4m away, is the adjoining wall with my bedroom.

Is the boiler likely to keep me awake at night if I put it in this
location?

  #34   Report Post  
IMM
 
Posts: n/a
Default


"John Aston" wrote in message
oups.com...
Thanks to everyone who contributed heating design ideas.

The design is finalised and I am considering placement of the
components.

I plan to put the 40kW condensing boiler (Keston C40) and cylinder in a
cupboard at one end of the bathroom. At the opposite end of the
bathroom, 4m away, is the adjoining wall with my bedroom.

Is the boiler likely to keep me awake at night if I put it in this
location?


Make sure the cupboard is well sealed and flimsey. You make need draught
stip on the doors to prevent sopunds getting oit. It does work.

Two Keston Celisus boilers are near the price of one 40kW Keston.


  #35   Report Post  
Andy Hall
 
Posts: n/a
Default

On Mon, 6 Dec 2004 11:09:39 -0000, "IMM" wrote:


"John Aston" wrote in message
roups.com...
Thanks to everyone who contributed heating design ideas.

The design is finalised and I am considering placement of the
components.

I plan to put the 40kW condensing boiler (Keston C40) and cylinder in a
cupboard at one end of the bathroom. At the opposite end of the
bathroom, 4m away, is the adjoining wall with my bedroom.

Is the boiler likely to keep me awake at night if I put it in this
location?


Make sure the cupboard is well sealed and flimsey. You make need draught
stip on the doors to prevent sopunds getting oit. It does work.

Two Keston Celisus boilers are near the price of one 40kW Keston.


You've been quiet for the last few days. Been ill or ?




--

..andy

To email, substitute .nospam with .gl


  #36   Report Post  
Bob Mannix
 
Posts: n/a
Default


"Andy Hall" wrote in message
...
On Mon, 6 Dec 2004 11:09:39 -0000, "IMM" wrote:


"John Aston" wrote in message
roups.com...
Thanks to everyone who contributed heating design ideas.

The design is finalised and I am considering placement of the
components.

I plan to put the 40kW condensing boiler (Keston C40) and cylinder in a
cupboard at one end of the bathroom. At the opposite end of the
bathroom, 4m away, is the adjoining wall with my bedroom.

Is the boiler likely to keep me awake at night if I put it in this
location?


Make sure the cupboard is well sealed and flimsey. You make need draught
stip on the doors to prevent sopunds getting oit. It does work.

Two Keston Celisus boilers are near the price of one 40kW Keston.


You've been quiet for the last few days. Been ill or ?


Leave him alone! Rarely is such lyrical prose posted here.. I love the idea
of sopunds getting oit. ;o)


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)


  #37   Report Post  
John Aston
 
Posts: n/a
Default

IMM wrote in message
...

"John Aston" wrote in message
oups.com...
Thanks to everyone who contributed heating design ideas.

The design is finalised and I am considering placement of the
components.

I plan to put the 40kW condensing boiler (Keston C40) and cylinder in a
cupboard at one end of the bathroom. At the opposite end of the
bathroom, 4m away, is the adjoining wall with my bedroom.

Is the boiler likely to keep me awake at night if I put it in this
location?


Make sure the cupboard is well sealed and flimsey. You make need draught
stip on the doors to prevent sopunds getting oit. It does work.

Two Keston Celisus boilers are near the price of one 40kW Keston.


I've heard that the Keston boiler is noisier because the flue fan needs to
go faster to get the air through a 2 inch flue. Any Keston owners out there
care to comment?


  #38   Report Post  
IMM
 
Posts: n/a
Default


"IMM" wrote in message
...

"John Aston" wrote in message
oups.com...
Thanks to everyone who contributed heating design ideas.

The design is finalised and I am considering placement of the
components.

I plan to put the 40kW condensing boiler (Keston C40) and cylinder in a
cupboard at one end of the bathroom. At the opposite end of the
bathroom, 4m away, is the adjoining wall with my bedroom.

Is the boiler likely to keep me awake at night if I put it in this
location?


Make sure the cupboard is well sealed and flimsey. You make need draught
stip on the doors to prevent sopunds getting oit. It does work.

Two Keston Celisus boilers are near the price of one 40kW Keston.


Typo. should be.. Make sure the cupboard is well sealed and not flimsey.
You make need draught strip on the doors to prevent sounds getting out. It
does work.




  #39   Report Post  
IMM
 
Posts: n/a
Default


"Andy Hall" wrote in message
...
On Mon, 6 Dec 2004 11:09:39 -0000, "IMM" wrote:


"John Aston" wrote in message
roups.com...
Thanks to everyone who contributed heating design ideas.

The design is finalised and I am considering placement of the
components.

I plan to put the 40kW condensing boiler (Keston C40) and cylinder in a
cupboard at one end of the bathroom. At the opposite end of the
bathroom, 4m away, is the adjoining wall with my bedroom.

Is the boiler likely to keep me awake at night if I put it in this
location?


Make sure the cupboard is well sealed and flimsey. You make need draught
stip on the doors to prevent sopunds getting oit. It does work.

Two Keston Celisus boilers are near the price of one 40kW Keston.


You've been quiet for the last few days. Been ill or ?


I'm as right as rain. I have been abroad jet setting.


  #40   Report Post  
IMM
 
Posts: n/a
Default


"John Aston" wrote in message
.. .
IMM wrote in message
...

"John Aston" wrote in message
oups.com...
Thanks to everyone who contributed heating design ideas.

The design is finalised and I am considering placement of the
components.

I plan to put the 40kW condensing boiler (Keston C40) and cylinder in

a
cupboard at one end of the bathroom. At the opposite end of the
bathroom, 4m away, is the adjoining wall with my bedroom.

Is the boiler likely to keep me awake at night if I put it in this
location?


Make sure the cupboard is well sealed and flimsey. You make need

draught
stip on the doors to prevent sopunds getting oit. It does work.

Two Keston Celisus boilers are near the price of one 40kW Keston.


I've heard that the Keston boiler is noisier because the flue fan needs to
go faster to get the air through a 2 inch flue. Any Keston owners out

there
care to comment?


They are a bit on the noisy side.


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