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  #1   Report Post  
Mike Hibbert
 
Posts: n/a
Default Central Heating question

Hi all,

I have been thinking about my central heating this morning as it seems to be
getting very toasty at the moment. We have a Combi boiler (Worcester Bosch
Highflow 400) which has a heat setting on it. There are TRV on all the rads
(except the bathroom - I assume to stop the boiler overheating if the TRV's
shut off) , but we dont have a room stat.

Are the TRV's really temperature controlled or do they simply reduce the
amount of water the rad can get? If that is the case, then with no room
stat, the only way I can control the overall temperature is by the boiler,
so I have to go into the garage and turn it down/up. Is this a normal set
up?

Normally I would leave the heating on 24*7 during the winter and control it
via the room stat so it would get to a reasonable temp and then switch off,
but now if I leave the heating on the boiler tuns all the time (this must be
expensive!!) and the bathroom is like a sauna. The missus loves it, but I
guess the heating bills will be huge!

Any thoughts?

Mike


  #2   Report Post  
BillR
 
Posts: n/a
Default Central Heating question

Mike Hibbert wrote:
Hi all,

I have been thinking about my central heating this morning as it
seems to be getting very toasty at the moment. We have a Combi boiler
(Worcester Bosch Highflow 400) which has a heat setting on it. There
are TRV on all the rads (except the bathroom - I assume to stop the
boiler overheating if the TRV's shut off) , but we dont have a room
stat.

Are the TRV's really temperature controlled or do they simply reduce
the amount of water the rad can get? If that is the case, then with
no room stat, the only way I can control the overall temperature is
by the boiler, so I have to go into the garage and turn it down/up.
Is this a normal set up?

Its normal for installers to fit TRVs on all rads because they can't be
bothered with the hassle of roomstat wiring...
Normally I would leave the heating on 24*7 during the winter and
control it via the room stat so it would get to a reasonable temp and
then switch off, but now if I leave the heating on the boiler tuns
all the time (this must be expensive!!) and the bathroom is like a
sauna. The missus loves it, but I guess the heating bills will be
huge!

Any thoughts?

Fit a programmable room stat. If wiring it up is a problem get one of the RF
models e.g. CM67 RF.


  #3   Report Post  
Set Square
 
Posts: n/a
Default Central Heating question

Mike Hibbert wrote:
Hi all,

I have been thinking about my central heating this morning as it
seems to be getting very toasty at the moment. We have a Combi boiler
(Worcester Bosch Highflow 400) which has a heat setting on it. There
are TRV on all the rads (except the bathroom - I assume to stop the
boiler overheating if the TRV's shut off) , but we dont have a room
stat.

Are the TRV's really temperature controlled or do they simply reduce
the amount of water the rad can get? If that is the case, then with
no room stat, the only way I can control the overall temperature is
by the boiler, so I have to go into the garage and turn it down/up.
Is this a normal set up?

Normally I would leave the heating on 24*7 during the winter and
control it via the room stat so it would get to a reasonable temp and
then switch off, but now if I leave the heating on the boiler tuns
all the time (this must be expensive!!) and the bathroom is like a
sauna. The missus loves it, but I guess the heating bills will be
huge!

Any thoughts?

Mike


Well, your system certainly wouldn't satisfy the latest building regs on
energy efficiency - because the system has to be capable of turning itself
off when the heating demand is met.

The simplest solution is to install a room stat - which really needs to be
in a room whose radiator *doesn't* have a TRV - otherwise they will fight.
You could probably put it in the hallway, and leave the TRV on that rad
fully open - or, even better, swap it for the conventional valve on the
bathroom rad.

--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is Black Hole!


  #4   Report Post  
Mike Hibbert
 
Posts: n/a
Default Central Heating question

"BillR" wrote in message
...
Mike Hibbert wrote:
Hi all,

I have been thinking about my central heating this morning as it
seems to be getting very toasty at the moment. We have a Combi boiler
(Worcester Bosch Highflow 400) which has a heat setting on it. There
are TRV on all the rads (except the bathroom - I assume to stop the
boiler overheating if the TRV's shut off) , but we dont have a room
stat.

Are the TRV's really temperature controlled or do they simply reduce
the amount of water the rad can get? If that is the case, then with
no room stat, the only way I can control the overall temperature is
by the boiler, so I have to go into the garage and turn it down/up.
Is this a normal set up?

Its normal for installers to fit TRVs on all rads because they can't be
bothered with the hassle of roomstat wiring...
Normally I would leave the heating on 24*7 during the winter and
control it via the room stat so it would get to a reasonable temp and
then switch off, but now if I leave the heating on the boiler tuns
all the time (this must be expensive!!) and the bathroom is like a
sauna. The missus loves it, but I guess the heating bills will be
huge!

Any thoughts?

Fit a programmable room stat. If wiring it up is a problem get one of the

RF
models e.g. CM67 RF.


Thanks Bill, it would still need wiring at the boiler end wouldn't it? Is
that a (relatively) straightforward job?



  #5   Report Post  
Set Square
 
Posts: n/a
Default Central Heating question

Mike Hibbert wrote:
"BillR" wrote in message
...
Fit a programmable room stat. If wiring it up is a problem get one
of the RF models e.g. CM67 RF.


Thanks Bill, it would still need wiring at the boiler end wouldn't
it? Is that a (relatively) straightforward job?


Presumably you have a programmer with a time switch which tells the heating
when to come on? There will be a cable connecting the CH ON terminal on the
programmer to an appropriate point on the boiler. This cable needs to be
diverted to go via the roomstat - so that the live feed only gets to the
boiler when the programmer and roomstat are *both* calling for heating. In
other words, the CH switch in the programmer and the roomstat both need to
be wired in series between the mains and the boiler. You may well have a
junction box somewhere to which the programmer and boiler are both
connected. If so, this probably has a link between the two terminals to
which the roomstat needs to be connected. If this is the case, you simply
need to remove the link and take 2 wires to the stat - probably to the COM
and NC terminals if there are more than 2. I assume that the pump is
integral with the boiler - or at least controlled by the boiler? If so, this
will take care of itself once you have the boiler under control.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is Black Hole!




  #6   Report Post  
Andy Hall
 
Posts: n/a
Default Central Heating question

On Sun, 07 Dec 2003 17:06:25 GMT, "Mike Hibbert"
wrote:

"BillR" wrote in message
...
Mike Hibbert wrote:
Hi all,

I have been thinking about my central heating this morning as it
seems to be getting very toasty at the moment. We have a Combi boiler
(Worcester Bosch Highflow 400) which has a heat setting on it. There
are TRV on all the rads (except the bathroom - I assume to stop the
boiler overheating if the TRV's shut off) , but we dont have a room
stat.

Are the TRV's really temperature controlled or do they simply reduce
the amount of water the rad can get? If that is the case, then with
no room stat, the only way I can control the overall temperature is
by the boiler, so I have to go into the garage and turn it down/up.
Is this a normal set up?

Its normal for installers to fit TRVs on all rads because they can't be
bothered with the hassle of roomstat wiring...
Normally I would leave the heating on 24*7 during the winter and
control it via the room stat so it would get to a reasonable temp and
then switch off, but now if I leave the heating on the boiler tuns
all the time (this must be expensive!!) and the bathroom is like a
sauna. The missus loves it, but I guess the heating bills will be
huge!

Any thoughts?

Fit a programmable room stat. If wiring it up is a problem get one of the

RF
models e.g. CM67 RF.


Thanks Bill, it would still need wiring at the boiler end wouldn't it? Is
that a (relatively) straightforward job?



Mike

I spotted a couple of things from your original post.

TRVs are fairly effective in that they do monitor the room temperature
(albeit they are a little influenced by being near the radiator).
There is a wax or equivalent capsule inside which expands with
temperature and reduces and ultimately stops the water flow. In that
sense they are somewhat more "analogue" than "digital" which is not a
bad thing anyway. Of course, you also have the effect in a house
that there is transfer of heat from room to room so the overall
environment is quite complex. However, they are effective for what
they are.

Adding a room thermostat is a good way to implement overall control of
the house temperature.

I completely agree with Bill, an RF thermostat would probably be a
good solution for you. Apart from the Honeywell CM67RF there is the
Danfoss TP75-RF (about to be superceded by TP7000-RF)

These consist of a remote unit which you can site anywhere, or even
take from room to room if you wanted. There is a clock and a
temperature setting and measuring function and the whole thing is
battery powered.

One useful capability is of night set back. This means that you can
drop the temperature over night by a few degrees rather than turning
off the heating completely. 6 degrees or so setback is fairly
typical. Apart from the improved comfort, depending on the system
and the house, doing this can also result in less use of energy as
well. One of the principles behind this is that in some systems and
houses, when the heating goes on in a cold house, there is an
overshoot past the set point and more energy is used. If the house
is not as cold then the overshoot is less. However this does all
depend on the complete environment of the system and the house thermal
characteristics. Also, with this type of room thermostat, the
temperature sensing is more sensitive and accurate than an old
fashioned bimetal strip type.

Moreover, there is also what is called a proportional control
facility. This basically turns the boiler on and off in proportion
to the heat required when the temperature is a degree or two either
side of the set point. The effect is that overshoot can be
practically eliminated.

Added to this, the boiler that you have is a modulating type which
will adjust heat output according to demand.
Overall, this sounds quite complex. In one sense it is - the
control theory for a system like this and a house is involved.

However, you don't need to be overly concerned.
The main points to achieve are that a) you are getting to the right
temperatures when you want them, b) that there is not significant
temperature overshoot when the system begins the start of a heating
period and c) that the boiler doesn't short cycle (= 30-60 second
burns) because it is producing too much heat.
In reality, you have to experiment a little until you are happy with
the settings.


Regarding installation, at the boiler end you have a receiver which is
connected to the boiler. You can download the installation manual
for the boiler and you will find a wiring diagram. The boiler has a
set of terminals with a permanent live and a switched live for the
heating. At present, these will have a link between them, I would
expect.

After removing the link, you would wire out to the receiver (which
should be located outside the case of the boiler) using the permanent
live and neutral and then the switched live, plus an earth if
required.

It's possible that you might already have a timeswitch on these two
terminals, although I note that some versions of this boiler have one
built in.

The best thing if there is a time switch already would be to set it to
24x7 as you are now and to use the clock function on the remote room
controller.

If you can run the wiring easily, there are non-RF versions of these
two programmers which cost a little less and have the same
functionality.

I hope that that helps. This is not a particularly difficult task
if you are comfortable with doing wiring. Obviously, sketch down
what you have before you start in case you need to revert back for any
reason.





..andy

To email, substitute .nospam with .gl
  #7   Report Post  
Mike Hibbert
 
Posts: n/a
Default Central Heating question


"Set Square" wrote in message
...
Mike Hibbert wrote:
"BillR" wrote in message
...
Fit a programmable room stat. If wiring it up is a problem get one
of the RF models e.g. CM67 RF.


Thanks Bill, it would still need wiring at the boiler end wouldn't
it? Is that a (relatively) straightforward job?


Presumably you have a programmer with a time switch which tells the

heating
when to come on? There will be a cable connecting the CH ON terminal on

the
programmer to an appropriate point on the boiler. This cable needs to be
diverted to go via the roomstat - so that the live feed only gets to the
boiler when the programmer and roomstat are *both* calling for heating. In
other words, the CH switch in the programmer and the roomstat both need to
be wired in series between the mains and the boiler. You may well have a
junction box somewhere to which the programmer and boiler are both
connected. If so, this probably has a link between the two terminals to
which the roomstat needs to be connected. If this is the case, you simply
need to remove the link and take 2 wires to the stat - probably to the COM
and NC terminals if there are more than 2. I assume that the pump is
integral with the boiler - or at least controlled by the boiler? If so,

this
will take care of itself once you have the boiler under control.
--
Cheers,
Set Square
______


Hello,

I have just pulled out the wiring diagram for the boiler and it looks ok
actually. I simply (!) need top wire in the live, switched live and neutral
from the stat and then remove a link between the live and switched live
points.


___
A / B-/\//\- C (room stat)
| | |
| | |
1 2 3 (control board)
\___/

Where A is live
B is switched live
C is Neutral

and the link beween 1 & 2 is to be removed

Cheers for the advice!

Mike







  #8   Report Post  
Set Square
 
Posts: n/a
Default Central Heating question

Mike Hibbert wrote:
______


Hello,

I have just pulled out the wiring diagram for the boiler and it looks
ok actually. I simply (!) need top wire in the live, switched live
and neutral from the stat and then remove a link between the live and
switched live points.


___
A / B-/\//\- C (room stat)
| | |
| | |
1 2 3 (control board)
\___/

Where A is live
B is switched live
C is Neutral

and the link beween 1 & 2 is to be removed

Cheers for the advice!

Mike


Should be a piece of cake then! As others have suggested, If you use a
wireless programmable stat you will need virtually no wiring and will also
be able to have different temperatures (or switch off completely) at
different times of day - even if you don't currently have a timeswitch in
the system.

--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is Black Hole!


  #9   Report Post  
The Natural Philosopher
 
Posts: n/a
Default Central Heating question

Mike Hibbert wrote:

Hi all,

I have been thinking about my central heating this morning as it seems to be
getting very toasty at the moment. We have a Combi boiler (Worcester Bosch
Highflow 400) which has a heat setting on it. There are TRV on all the rads
(except the bathroom - I assume to stop the boiler overheating if the TRV's
shut off) , but we dont have a room stat.

Are the TRV's really temperature controlled or do they simply reduce the
amount of water the rad can get? If that is the case, then with no room
stat, the only way I can control the overall temperature is by the boiler,
so I have to go into the garage and turn it down/up. Is this a normal set
up?



Each TRV shuts down when its room gets warm enough.

Eventually teh heat loss from te hot water is so low, that teh boiler
shuts off as return flow temps exceed 60.

Your pump will run all the time, but the boiler won't.



Normally I would leave the heating on 24*7 during the winter and control it
via the room stat so it would get to a reasonable temp and then switch off,
but now if I leave the heating on the boiler tuns all the time (this must be
expensive!!) and the bathroom is like a sauna. The missus loves it, but I
guess the heating bills will be huge!



Not necessarily. You COULD fit a stat, but why bother? Better if teh
house is decentluy insulated to run teh CH off a timer and set it to
come on at susnet, and go off around midnight, and again a little before
dawn.



Any thoughts?

Mike





  #10   Report Post  
The Natural Philosopher
 
Posts: n/a
Default Central Heating question

Set Square wrote:

Mike Hibbert wrote:

Hi all,

I have been thinking about my central heating this morning as it
seems to be getting very toasty at the moment. We have a Combi boiler
(Worcester Bosch Highflow 400) which has a heat setting on it. There
are TRV on all the rads (except the bathroom - I assume to stop the
boiler overheating if the TRV's shut off) , but we dont have a room
stat.

Are the TRV's really temperature controlled or do they simply reduce
the amount of water the rad can get? If that is the case, then with
no room stat, the only way I can control the overall temperature is
by the boiler, so I have to go into the garage and turn it down/up.
Is this a normal set up?

Normally I would leave the heating on 24*7 during the winter and
control it via the room stat so it would get to a reasonable temp and
then switch off, but now if I leave the heating on the boiler tuns
all the time (this must be expensive!!) and the bathroom is like a
sauna. The missus loves it, but I guess the heating bills will be
huge!

Any thoughts?

Mike


Well, your system certainly wouldn't satisfy the latest building regs on
energy efficiency - because the system has to be capable of turning itself
off when the heating demand is met.



The booer will turn itself off. It has its own stat on teh water temp.


The simplest solution is to install a room stat - which really needs to be
in a room whose radiator *doesn't* have a TRV - otherwise they will fight.
You could probably put it in the hallway, and leave the TRV on that rad
fully open - or, even better, swap it for the conventional valve on the
bathroom rad.






  #11   Report Post  
Set Square
 
Posts: n/a
Default Central Heating question

In an earlier contribution to this discussion,
The Natural Philosopher wrote:



The booer will turn itself off. It has its own stat on teh water temp.

??????
boiler?


ISTR that you said something similar in an earlier thread. Whilst true, it
still wouldn't satisfy the new regs because it will come on again when *it*
cools down - even if no heating zones are calling for heat.

--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is Black Hole!


  #12   Report Post  
Mike Hibbert
 
Posts: n/a
Default Central Heating question

"The Natural Philosopher" wrote in message
...
Set Square wrote:

Mike Hibbert wrote:

Hi all,

I have been thinking about my central heating this morning as it
seems to be getting very toasty at the moment. We have a Combi boiler
(Worcester Bosch Highflow 400) which has a heat setting on it. There
are TRV on all the rads (except the bathroom - I assume to stop the
boiler overheating if the TRV's shut off) , but we dont have a room
stat.

Are the TRV's really temperature controlled or do they simply reduce
the amount of water the rad can get? If that is the case, then with
no room stat, the only way I can control the overall temperature is
by the boiler, so I have to go into the garage and turn it down/up.
Is this a normal set up?

Normally I would leave the heating on 24*7 during the winter and
control it via the room stat so it would get to a reasonable temp and
then switch off, but now if I leave the heating on the boiler tuns
all the time (this must be expensive!!) and the bathroom is like a
sauna. The missus loves it, but I guess the heating bills will be
huge!

Any thoughts?

Mike


Well, your system certainly wouldn't satisfy the latest building regs on
energy efficiency - because the system has to be capable of turning

itself
off when the heating demand is met.



The booer will turn itself off. It has its own stat on teh water temp.



Yes, but it doesn't measure the room temp, on nights when it has been cold,
I have to turn the boiler up or it gets cold, and then the next day the
place is boiling so I have to turn it down again. A room stat would give
consistency.




  #13   Report Post  
Peter
 
Posts: n/a
Default Central Heating question

This is all rubbish, after 20 years in the controls businessI have concluded
the only solution is a rectal thermometer worn by SWHBO with an RF link to
the main heating plant. In this way the system responds to her core
temperature and ignores all the other irrelevant factors.
"The Natural Philosopher" wrote in message
...
Mike Hibbert wrote:

Hi all,

I have been thinking about my central heating this morning as it seems

to be
getting very toasty at the moment. We have a Combi boiler (Worcester

Bosch
Highflow 400) which has a heat setting on it. There are TRV on all the

rads
(except the bathroom - I assume to stop the boiler overheating if the

TRV's
shut off) , but we dont have a room stat.

Are the TRV's really temperature controlled or do they simply reduce the
amount of water the rad can get? If that is the case, then with no room
stat, the only way I can control the overall temperature is by the

boiler,
so I have to go into the garage and turn it down/up. Is this a normal

set
up?



Each TRV shuts down when its room gets warm enough.

Eventually teh heat loss from te hot water is so low, that teh boiler
shuts off as return flow temps exceed 60.

Your pump will run all the time, but the boiler won't.



Normally I would leave the heating on 24*7 during the winter and control

it
via the room stat so it would get to a reasonable temp and then switch

off,
but now if I leave the heating on the boiler tuns all the time (this

must be
expensive!!) and the bathroom is like a sauna. The missus loves it, but

I
guess the heating bills will be huge!



Not necessarily. You COULD fit a stat, but why bother? Better if teh
house is decentluy insulated to run teh CH off a timer and set it to
come on at susnet, and go off around midnight, and again a little before
dawn.



Any thoughts?

Mike







  #14   Report Post  
Owain
 
Posts: n/a
Default Central Heating question

"Peter" wrote
| This is all rubbish, after 20 years in the controls businessI have
| concluded the only solution is a rectal thermometer worn by SWHBO

she who has ...; no I'm not going there

| with an RF link to the main heating plant. In this way the system
| responds to her core temperature and ignores all the other
| irrelevant factors.

I would quite like an infra-red thermometer under the desk aimed at my
kneecaps, as they're the bits of me that get coldest whilst sitting at the
PC. And one over the bedhead aimed at my nose, as ditto whilst in bed.

Owain


  #15   Report Post  
The Natural Philosopher
 
Posts: n/a
Default Central Heating question

Set Square wrote:

In an earlier contribution to this discussion,
The Natural Philosopher wrote:



The booer will turn itself off. It has its own stat on teh water temp.

??????
boiler?


ISTR that you said something similar in an earlier thread. Whilst true, it
still wouldn't satisfy the new regs because it will come on again when *it*
cools down - even if no heating zones are calling for heat.



No, not when IT cools down, when the water circulating through it cools
down, and if you have insulated pipes and no demand, that will be an
awfully long time. In my case well over ten minutes to overcome the
thermostat hysteresis. Then a quick minute burn up to temp, and a ten
minute gap again.

In fact since I superlagged the CH pipes in the attic, its even longer now.








  #16   Report Post  
The Natural Philosopher
 
Posts: n/a
Default Central Heating question

Mike Hibbert wrote:

"The Natural Philosopher" wrote in message
...

Set Square wrote:


Mike Hibbert wrote:


Hi all,

I have been thinking about my central heating this morning as it
seems to be getting very toasty at the moment. We have a Combi boiler
(Worcester Bosch Highflow 400) which has a heat setting on it. There
are TRV on all the rads (except the bathroom - I assume to stop the
boiler overheating if the TRV's shut off) , but we dont have a room
stat.

Are the TRV's really temperature controlled or do they simply reduce
the amount of water the rad can get? If that is the case, then with
no room stat, the only way I can control the overall temperature is
by the boiler, so I have to go into the garage and turn it down/up.
Is this a normal set up?

Normally I would leave the heating on 24*7 during the winter and
control it via the room stat so it would get to a reasonable temp and
then switch off, but now if I leave the heating on the boiler tuns
all the time (this must be expensive!!) and the bathroom is like a
sauna. The missus loves it, but I guess the heating bills will be
huge!

Any thoughts?

Mike


Well, your system certainly wouldn't satisfy the latest building regs on
energy efficiency - because the system has to be capable of turning

itself

off when the heating demand is met.



The booer will turn itself off. It has its own stat on teh water temp.




Yes, but it doesn't measure the room temp, on nights when it has been cold,
I have to turn the boiler up or it gets cold, and then the next day the
place is boiling so I have to turn it down again. A room stat would give
consistency.



TRV's are room stats you burk!








  #17   Report Post  
The Natural Philosopher
 
Posts: n/a
Default Central Heating question

Peter wrote:

This is all rubbish, after 20 years in the controls businessI have concluded
the only solution is a rectal thermometer worn by SWHBO with an RF link to
the main heating plant. In this way the system responds to her core
temperature and ignores all the other irrelevant factors.



There is definitely something to be said for that approach...


  #18   Report Post  
Andrew Gabriel
 
Posts: n/a
Default Central Heating question

In article ,
The Natural Philosopher writes:
Peter wrote:

This is all rubbish, after 20 years in the controls businessI have concluded
the only solution is a rectal thermometer worn by SWHBO with an RF link to
the main heating plant. In this way the system responds to her core
temperature and ignores all the other irrelevant factors.


There is definitely something to be said for that approach...


The building control inspection could be rather interesting...

--
Andrew Gabriel
  #19   Report Post  
IMM
 
Posts: n/a
Default Central Heating question


"Set Square" wrote in message
...


Cheers,
Set Square
______
Please reply to newsgroup. Reply address is Black Hole!


Or reply to IMM as this loon thinks he is me.


---
--

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.548 / Virus Database: 341 - Release Date: 05/12/2003


  #20   Report Post  
BigWallop
 
Posts: n/a
Default Central Heating question


"Andrew Gabriel" wrote in message
...
In article ,
The Natural Philosopher writes:
Peter wrote:

This is all rubbish, after 20 years in the controls businessI have

concluded
the only solution is a rectal thermometer worn by SWHBO with an RF link

to
the main heating plant. In this way the system responds to her core
temperature and ignores all the other irrelevant factors.


There is definitely something to be said for that approach...


The building control inspection could be rather interesting...


Andrew Gabriel


As long as you don't make an arse of it.




  #21   Report Post  
Ed Sirett
 
Posts: n/a
Default Central Heating question

On Sun, 07 Dec 2003 19:59:08 +0000, The Natural Philosopher wrote:




Well, your system certainly wouldn't satisfy the latest building regs on
energy efficiency - because the system has to be capable of turning itself
off when the heating demand is met.



The boiler will turn itself off. It has its own stat on teh water temp.



Yes but that is not enough to comply with Part L whcih the OP does not
have to do since this is not a new replacement.


The simplest solution is to install a room stat - which really needs to be
in a room whose radiator *doesn't* have a TRV - otherwise they will fight.
You could probably put it in the hallway, and leave the TRV on that rad
fully open - or, even better, swap it for the conventional valve on the
bathroom rad.

Agreed this is simpler that going for all TRVs and 'smart' bypass units
with interlocks.

--
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  #22   Report Post  
IMM
 
Posts: n/a
Default Central Heating question


"The Natural Philosopher" wrote in message
...
Set Square wrote:

Mike Hibbert wrote:

Hi all,

I have been thinking about my central heating this morning as it
seems to be getting very toasty at the moment. We have a Combi boiler
(Worcester Bosch Highflow 400) which has a heat setting on it. There
are TRV on all the rads (except the bathroom - I assume to stop the
boiler overheating if the TRV's shut off) , but we dont have a room
stat.

Are the TRV's really temperature controlled or do they simply reduce
the amount of water the rad can get? If that is the case, then with
no room stat, the only way I can control the overall temperature is
by the boiler, so I have to go into the garage and turn it down/up.
Is this a normal set up?

Normally I would leave the heating on 24*7 during the winter and
control it via the room stat so it would get to a reasonable temp and
then switch off, but now if I leave the heating on the boiler tuns
all the time (this must be expensive!!) and the bathroom is like a
sauna. The missus loves it, but I guess the heating bills will be
huge!

Any thoughts?

Mike


Well, your system certainly wouldn't satisfy the latest building regs on
energy efficiency - because the system has to be capable of turning

itself
off when the heating demand is met.



The booer will turn itself off. It has its own stat on teh water temp.


Duh! Then it will cycle. The regs say it requires a control interlock.
Which mean when all the house is satisfied the burner is off.



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  #23   Report Post  
geoff
 
Posts: n/a
Default Central Heating question

In message , IMM
writes

Well, your system certainly wouldn't satisfy the latest building regs on
energy efficiency - because the system has to be capable of turning

itself
off when the heating demand is met.



The booer will turn itself off. It has its own stat on teh water temp.


Duh! Then it will cycle. The regs say it requires a control interlock.
Which mean when all the house is satisfied the burner is off.

How many sheep are we talking about here?

--
geoff
  #24   Report Post  
IMM
 
Posts: n/a
Default Central Heating question


"geoff" wrote in message
news
In message , IMM
writes

Well, your system certainly wouldn't satisfy the latest building regs

on
energy efficiency - because the system has to be capable of turning

itself
off when the heating demand is met.



The booer will turn itself off. It has its own stat on teh water temp.


Duh! Then it will cycle. The regs say it requires a control interlock.
Which mean when all the house is satisfied the burner is off.


How many sheep are we talking about here?


Good question Maxie! Our snotty uni person is surrounded by them. He was
banished from mixing with normal people.


---
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  #25   Report Post  
The Natural Philosopher
 
Posts: n/a
Default Central Heating question

geoff wrote:

In message , IMM
writes


Well, your system certainly wouldn't satisfy the latest building
regs on
energy efficiency - because the system has to be capable of turning


itself

off when the heating demand is met.




The booer will turn itself off. It has its own stat on teh water temp.



Duh! Then it will cycle. The regs say it requires a control interlock.
Which mean when all the house is satisfied the burner is off.

How many sheep are we talking about here?


Dunno.

I actually don't run my central heating when the whole house is warm enough.

And teh boiler cycles in teh house stat when one is used anyway. So waht
is the difference?

Nothing, except the pump runs all the time.

There is no requirement to make sure your pump doesn't run when the
whole house is warm.




  #26   Report Post  
IMM
 
Posts: n/a
Default Central Heating question


"The Natural Philosopher" wrote in message
...

There is no requirement to make sure your pump doesn't run when the
whole house is warm.


That is true, and in many cases it is best to keep it running, especially
when having an outside weather compensator. But switching out the burner
when the house is up to temp is pretty well necessary.


---
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  #27   Report Post  
Zymurgy
 
Posts: n/a
Default Central Heating question

"Mike Hibbert" wrote
Hi all,

We have a Combi boiler ... which has a heat setting on it.
There are TRV on all the rads (except the bathroom - I assume to stop the
boiler overheating if the TRV's shut off) , but we dont have a room stat.

Are the TRV's really temperature controlled or do they simply reduce the
amount of water the rad can get? If that is the case, then with no room
stat, the only way I can control the overall temperature is by the boiler,
so I have to go into the garage and turn it down/up. Is this a normal set
up?

Normally I would leave the heating on 24*7 during the winter and control it
via the room stat so it would get to a reasonable temp and then switch off,
but now if I leave the heating on the boiler tuns all the time (this must be
expensive!!) and the bathroom is like a sauna.


This is almost if not exactly the same as my setup.

There's no room stat and I control the overall temperature via the
control on the boiler (which for me is in the kitchen).

I have TRV's on all the rads, including now the recently installed
towel rail, however, I don't turn off any of the TRV's.

Maybe i've done wrong by TRV'ing the last radiator, but I don't know
whether the lack of a room stat is an issue. I suppose it'd save
visiting the boiler !

I tend to whack the TRV's on max and keep the boiler on low rather
than the reverse.

Cheers,

Paul.
  #28   Report Post  
Christian McArdle
 
Posts: n/a
Default Central Heating question

In my case well over ten minutes to overcome the thermostat
hysteresis. Then a quick minute burn up to temp, and a ten
minute gap again.


So your boiler runs 10% of the time during the middle of the day when no
heating is required?

This is simply not allowed for a new system. You might think it acceptable.
HMG thinks not. If no heat is required, the boiler and water must be allowed
to cool down. The requirement is pretty clearly worded (but only applies to
gas/oil, not solid fuel).

Christian.


  #29   Report Post  
Christian McArdle
 
Posts: n/a
Default Central Heating question

I tend to whack the TRV's on max and keep the boiler on low
rather than the reverse.


The TRVs sense room temperature. They should be set at around 21C, so that
the radiators turn themselves off when the room gets to temperature. Many
people erroneously think that they are "power" controls rather than
"temperature" controls and think the room will heat quicker on a higher
setting. They are wrong. The radiator will get to the same high temperature
whatever the setting, provided the room is colder than the selected
temperature. I really wish TRVs were marked in Celcius, as people would
understand the meaning rather than the ambiguous 1-6 thing.

The boiler control is probably the output water temperature. This will
affect how hot the radiators get and will affect their output power. If you
set this too low on a conventional boiler, you may get some condensing
action, which may corrode the heat exchanger. However, lower settings get
better thermodynamic efficiency. On a condensing boiler, the heat exchanger
is designed to condense, so set it as low as is effective.

Maybe i've done wrong by TRV'ing the last radiator,


If you have TRVs on all radiators, or you have an S-plan system with room
stat, you need an (preferably automatic) bypass valve on the system.
Otherwise, the water circuit can be entirely blocked, which can cause
problems for the boiler circulation and any pump overrun.

but I don't know whether the lack of a room stat is an issue.


It is. It reduces the efficiency, causing you to waste energy by continuing
to heat water that isn't required.

Christian.



"Zymurgy" wrote in message
om...
"Mike Hibbert" wrote
Hi all,

We have a Combi boiler ... which has a heat setting on it.
There are TRV on all the rads (except the bathroom - I assume to stop

the
boiler overheating if the TRV's shut off) , but we dont have a room

stat.

Are the TRV's really temperature controlled or do they simply reduce the
amount of water the rad can get? If that is the case, then with no room
stat, the only way I can control the overall temperature is by the

boiler,
so I have to go into the garage and turn it down/up. Is this a normal

set
up?

Normally I would leave the heating on 24*7 during the winter and control

it
via the room stat so it would get to a reasonable temp and then switch

off,
but now if I leave the heating on the boiler tuns all the time (this

must be
expensive!!) and the bathroom is like a sauna.


This is almost if not exactly the same as my setup.

There's no room stat and I control the overall temperature via the
control on the boiler (which for me is in the kitchen).

I have TRV's on all the rads, including now the recently installed
towel rail, however, I don't turn off any of the TRV's.

Maybe i've done wrong by TRV'ing the last radiator, but I don't know
whether the lack of a room stat is an issue. I suppose it'd save
visiting the boiler !

I tend to whack the TRV's on max and keep the boiler on low rather
than the reverse.

Cheers,

Paul.



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