I'm having a new CH/HW system installed from scratch (to replace a
somewhat antique, expensive and broken warm air/gravity system). Our
chosen plumber has recommended:

Vaillant Ecotec 630 condensing boiler
Santon Premier Plus unvented pressurized cylinder
15 radiators
for a 5-bed house.

He seems to be competent, but any comments would be appreciated. Is
mains pressure HW the way to go? (We already have a CW tank in the
loft, which would go.)

I am particularly interested in the safety and servicing requirements
of unvented systems.
http://www.gasapplianceguide.co.uk/M...er_Systems.htm
gives warnings, but is it partisan?

We already have a shower pump fitted in one of the bathrooms. Is this
permitted under the bye-law that prevents pumping from mains pressure
systems, or does that only apply to combi systems?

thanks,
Andrew.

"Andrew Haylett" wrote in message
ps.com...
I'm having a new CH/HW system installed from scratch (to replace a
somewhat antique, expensive and broken warm air/gravity system). Our
chosen plumber has recommended:

Vaillant Ecotec 630 condensing boiler

Good boiler.

Santon Premier Plus unvented pressurized cylinder

Bzzzt. Wrong. This what they can do.
http://www.waterheaterblast.com

Tell him to fit an integrated heat bank (thermal store with a plate heat
exchanger). This will outperform the unvented cylinder and no annual
service charge. Unvented cylinders require an annual charge of £60-£100.
If he says otherwise take no notce. That is £2,000 over 20 years for
storing water.

15 radiators
for a 5-bed house.

He seems to be competent, but any comments would be appreciated. Is
mains pressure HW the way to go?

No.

(We already have a CW tank in the
loft, which would go.)

I am particularly interested in the safety and servicing requirements
of unvented systems.
http://www.gasapplianceguide.co.uk/M...er_Systems.htm
gives warnings, but is it partisan?

See above.

We already have a shower pump fitted in one of the bathrooms. Is this
permitted under the bye-law that prevents pumping from mains pressure
systems, or does that only apply to combi systems?

You can't have a pump on any mains pipe. Is the mains pressure and flow
good? If so then go heat bank. They provide a wonderful buffer for the
boiler and the CH circuit. You can have TRVs on all rads using a Grundfos
Alpha pump too. No electric wall stat. Boiler cycling is elinminated.

In article ews.net,
Doctor Drivel wrote:
You can have TRVs on all rads using a Grundfos
Alpha pump too. No electric wall stat. Boiler cycling is elinminated.

Poor advice. A programmable wall stat saves energy as well as making the
house more comfortable.

--
*I didn't fight my way to the top of the food chain to be a vegetarian.

Dave Plowman London SW
To e-mail, change noise into sound.

On 11 Aug 2006 14:59:02 -0700 someone who may be "Andrew Haylett"
wrote this:-

I am particularly interested in the safety and servicing requirements
of unvented systems.

If installed and maintained properly they are reasonably safe. Not
100% safe, but nothing else is either.

Annual servicing costs money (and I suspect the costs will only ever
go up) just to store some hot water. A nice little earner if one can
get it.

http://www.gasapplianceguide.co.uk/M...er_Systems.htm
gives warnings, but is it partisan?

I agree with the ticks and crosses at the bottom.

Were I doing what you are doing at the moment I would look very
seriously at the Conus 502 supplied by multiple heat sources
http://www.consolar.co.uk/index.php?...= 2&Itemid=16


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

"David Hansen" wrote in message
...
On 11 Aug 2006 14:59:02 -0700 someone who may be "Andrew Haylett"
wrote this:-

I am particularly interested in the safety and servicing requirements
of unvented systems.

If installed and maintained properly they are reasonably safe. Not
100% safe, but nothing else is either.

Annual servicing costs money (and I suspect the costs will only ever
go up) just to store some hot water. A nice little earner if one can
get it.

http://www.gasapplianceguide.co.uk/M...er_Systems.htm
gives warnings, but is it partisan?

I agree with the ticks and crosses at the bottom.

Were I doing what you are doing at the moment I would look very
seriously at the Conus 502 supplied by multiple heat sources
http://www.consolar.co.uk/index.php?...= 2&Itemid=16


This is a very clever design to maintain stratification within the cylinder.
It is good for solar applications. I would go for heat bank (thermal store
with a plate heat exchanger) with a more efficient plate. Range, Nu-Heat,
DPS, etc do them. I would have a blending valve (UFH models) on the flow
and return of the boiler to ensure condensing operation and swift reheat. A
plate heat exchanger as opposed to a coil is far more efficient and delivers
higher flows than a coil (that gas appliance guide does not mention plates
being out of date). Also plate heat exchangers can operate at higher
pressures, hence higher flows than unvented cylinders. Also have a
Magnaclean filter on the CH return to the heat bank cylinder. This ensures
no sludge build up.

Andrew Haylett wrote:
I'm having a new CH/HW system installed from scratch (to replace a
somewhat antique, expensive and broken warm air/gravity system). Our
chosen plumber has recommended:

Vaillant Ecotec 630 condensing boiler
Santon Premier Plus unvented pressurized cylinder
15 radiators
for a 5-bed house.

He seems to be competent, but any comments would be appreciated. Is
mains pressure HW the way to go? (We already have a CW tank in the
loft, which would go.)


IMHO yes. for a 5 bed house.

I am particularly interested in the safety and servicing requirements
of unvented systems.
http://www.gasapplianceguide.co.uk/M...er_Systems.htm
gives warnings, but is it partisan?


I put mine in the loft, where even if it blows up the worst it would so
is drip scalding water into a bedroom. However the thing is covered with
safety valves and overflow and safety pipes. Needs a competent plumber,
but the results are worth it in terms of sheer volume of hot water
available for showers, or in my case, baths full to the plugholes and a
good book, a cup of coffee and a packet of fags, and a portable radio..

We already have a shower pump fitted in one of the bathrooms. Is this
permitted under the bye-law that prevents pumping from mains pressure
systems, or does that only apply to combi systems?

You scrap that as well. Won't be needed.


thanks,
Andrew.

"The Natural Philosopher" wrote in message
...
Andrew Haylett wrote:
I'm having a new CH/HW system installed from scratch (to replace a
somewhat antique, expensive and broken warm air/gravity system). Our
chosen plumber has recommended:

Vaillant Ecotec 630 condensing boiler
Santon Premier Plus unvented pressurized cylinder
15 radiators
for a 5-bed house.

He seems to be competent, but any comments would be appreciated. Is
mains pressure HW the way to go? (We already have a CW tank in the
loft, which would go.)


IMHO yes. for a 5 bed house.

I am particularly interested in the safety and servicing requirements
of unvented systems.
http://www.gasapplianceguide.co.uk/M...er_Systems.htm
gives warnings, but is it partisan?


I put mine in the loft, where even if it blows up the worst it would so is
drip scalding water into a bedroom. However the thing is covered with
safety valves and overflow and safety pipes. Needs a competent plumber,
but the results are worth it in terms of sheer volume of hot water
available for showers, or in my case, baths full to the plugholes and a
good book, a cup of coffee and a packet of fags, and a portable radio..

We already have a shower pump fitted in one of the bathrooms. Is this
permitted under the bye-law that prevents pumping from mains pressure
systems, or does that only apply to combi systems?

You scrap that as well. Won't be needed.

You really don't know, do you.

Andrew Haylett wrote:
I'm having a new CH/HW system installed from scratch (to replace a
somewhat antique, expensive and broken warm air/gravity system). Our
chosen plumber has recommended:

Vaillant Ecotec 630 condensing boiler
Santon Premier Plus unvented pressurized cylinder
15 radiators
for a 5-bed house.

Wow, thanks for all the help. I'm a CH neophyte so all information is
helpful. A few (quite a few) follow-up questions to help my learning
experience.

Mains pressure. Yes, there are some concerns about that. When the
plumber first measured the flow rate at a tap it was about 15l/min.
They replaced the stopcock at the entry point (it was locked solid) and
maybe they fiddled with something, but he said he can now measure
20l/min, which he professes to be adequate. What he wants to do is run
22mm from the entry point (currently 15mm) all the way up to the boiler
to improve the flow rate/pressure. (The boiler is to be on the first
floor, in the airing cupboard.) Is that a helpful thing to do, given
that the rest of the system is 15mm which will presumably limit the
flow rate at the tap?

What are the implications of the mains water pressure falling below a
certain level? Sub-standard performance at the taps/shower head, or
worse?

Location. He offered to put the boiler in the loft (makes the flue a
bit easier if mounted on the side wall). I demurred since it seemed we
weren't going to have much room for clothes in the airing cupboard
anyway due to the size of the cylinder, so might as well stick the
boiler there, and because we don't have a 'proper' loft ladder so I was
concerned about servicing access. But it has been suggested AIUI that
both the boiler and the cylinder could be put in the loft, with safety
advantages. I'll ask him about that.

Shower pumps. He didn't mention about getting rid of the one we have.
I guess I don't fully understand the regs. I thought as it was pumping
out of the cylinder then it would be OK - or does having a pressurized
system mean that the whole house effectively becomes an extension of
the mains?

Unvented/heat store. I think I understand how the latter works. I
guess it's a bit like a combi where the HW to the taps is heated on
demand, except that the heating is done via a pre-heated body of water,
right? How large is a typical thermal store compared with an unvented
cylinder? How common, relatively speaking, are the two types of
system? And are there any ease-of-installation issues either way?

Could the Vaillant boiler already specced drive a vented system? I
guess the boiler just sees an indirect system either way, whether
heating a pressurized body of water or a thermal store.

Safety/maintenance. That's obviously a concern with 6 people in the
house - but how prone are unvented systems to blow up? Do they have a
bad safety record (assuming appropriate maintenance)? I'll check with
the plumber about servicing costs.

He hasn't said anything about building control approval for an unvented
system. Whose job would this be?

TRV/room stat. I'll skirt clear of this debate. ;-) He's fitting TRVs
throughout, plus an RF room controller. Hopefully that will give us
enough flexibility. I haven't considered zoning - didn't even know
about it - but will ask anyway. I would *think* that TRVs will give
enough flexibility to save energy in lesser used areas, e.g. spare
room, utility room, etc.

many thanks again,
Andrew.

On 2006-08-12 23:43:12 +0100, "Andrew Haylett" said:


Andrew Haylett wrote:
I'm having a new CH/HW system installed from scratch (to replace a
somewhat antique, expensive and broken warm air/gravity system). Our
chosen plumber has recommended:

Vaillant Ecotec 630 condensing boiler
Santon Premier Plus unvented pressurized cylinder
15 radiators
for a 5-bed house.

Wow, thanks for all the help. I'm a CH neophyte so all information is
helpful. A few (quite a few) follow-up questions to help my learning
experience.

Mains pressure. Yes, there are some concerns about that. When the
plumber first measured the flow rate at a tap it was about 15l/min.
They replaced the stopcock at the entry point (it was locked solid) and
maybe they fiddled with something, but he said he can now measure
20l/min, which he professes to be adequate.

It is if you just want to run one shower at a time or fill one bath -
not if you want to do more than this.

Also, it would be a good idea to check this at peak water usage times
and the times that you are likely to want to shower or bath.


What he wants to do is run
22mm from the entry point (currently 15mm) all the way up to the boiler
to improve the flow rate/pressure.

This may well improve the flow rate depending on the supply.


(The boiler is to be on the first
floor, in the airing cupboard.) Is that a helpful thing to do, given
that the rest of the system is 15mm which will presumably limit the
flow rate at the tap?

It depends on the length of the runs. Unless they are particularly
long - i.e. one side of the house to the other - that should be OK for
showers. The bath plumbing may already be 22mm - it usually is if
there is a roof tank system originally.



What are the implications of the mains water pressure falling below a
certain level? Sub-standard performance at the taps/shower head, or
worse?

Substandard performance and variation in flow as other things are used.
A thermostatic valve on showers will maintain temperature reasonable
well unless there are gross changes in available flow.



Location. He offered to put the boiler in the loft (makes the flue a
bit easier if mounted on the side wall). I demurred since it seemed we
weren't going to have much room for clothes in the airing cupboard
anyway due to the size of the cylinder, so might as well stick the
boiler there, and because we don't have a 'proper' loft ladder so I was
concerned about servicing access. But it has been suggested AIUI that
both the boiler and the cylinder could be put in the loft, with safety
advantages. I'll ask him about that.

You would have to check the construction in the loft if the cylinder is
to go up there. Should be OK if it goes in the position of an
existing storage tank but needs to be checked - it's a lot of weight if
you have a large cylinder. If the boiler goes up there, the area
from the access hatch to it must be boarded and there must be a safety
rail around the hatch.




Shower pumps. He didn't mention about getting rid of the one we have.
I guess I don't fully understand the regs. I thought as it was pumping
out of the cylinder then it would be OK - or does having a pressurized
system mean that the whole house effectively becomes an extension of
the mains?

In effect, yes. The pump would have to go.



Unvented/heat store. I think I understand how the latter works. I
guess it's a bit like a combi where the HW to the taps is heated on
demand, except that the heating is done via a pre-heated body of water,
right? How large is a typical thermal store compared with an unvented
cylinder? How common, relatively speaking, are the two types of
system? And are there any ease-of-installation issues either way?

A thermal store can be run at 75-80 degrees as opposed to the 60
degrees of stored HW. The implication of that is that for an
equivalent amount of HW production, the thermal store cylinder can be
3/4 of the size of a storage cylinder. However, there are
additional plumbing components such as valves, pump and a heat
exchanger. By the time those are added, there is not really any
saving of space. Also a thermal store needs some kind of header tank
to supply the water in the main part of the cylinder because this is
vented. Either this can be a small tank in the loft, or if the
cylinder goes in the loft, there are thermal stores with the header
tank integrated on the top. Again by the time you add this, there is
no space saving. On the other hand, space may not be as critical in
the loft.
If you want an airing cupboard, you can always put a small radiator in there.





Could the Vaillant boiler already specced drive a vented system? I
guess the boiler just sees an indirect system either way, whether
heating a pressurized body of water or a thermal store.

If you use an indirect store, there are, in effect, three lots of water.

- The primary, which runs through the boiler, the heating circuit and a
coil in the cylinder. This can be sealed and pressurised or open
vented according to boiler requirements and preference. There are a
lot of advantages in going for sealed and no real disadvantages.

- The water in the store cylinder. This is open vented and is
circulated, on HW demand between store and heat exchanger. Having it
open vented gets around the regulatory requirements of a pressurised
cylinder.

- The HW being heated from the mains. With a thermal store, there is
again no large volume storage in this part either.



Safety/maintenance. That's obviously a concern with 6 people in the
house - but how prone are unvented systems to blow up? Do they have a
bad safety record (assuming appropriate maintenance)?

They are widely fitted in many countries outside the UK and do not have
a bad reputation or safety record.


I'll check with
the plumber about servicing costs.

He hasn't said anything about building control approval for an unvented
system. Whose job would this be?

He needs to have a particular training and certification to
install/service an unvented system. Ask him about that. Assuming he
does, then he can self certify the installation and there is no need
for other approvals.


TRV/room stat. I'll skirt clear of this debate. ;-) He's fitting TRVs
throughout, plus an RF room controller. Hopefully that will give us
enough flexibility. I haven't considered zoning - didn't even know
about it - but will ask anyway. I would *think* that TRVs will give
enough flexibility to save energy in lesser used areas, e.g. spare
room, utility room, etc.

You could get him to fit TRVs on all the radiators - even the one where
the room thermostat is going. Normally, the radiator in that location
does not have a TRV in order to prevent the two controls conflicting.
However, you may find that the initial location for the room thermostat
is not ideal for one reason or another - for example a hallway and
someone leaves the door open or living room and you want a separate
log/gas fire or something. Either can affect the behaviour of the
heating in an unwanted way.

If you fully open the TRV on the radiator where the room thermostat is
located, then that room becomes the "controlling" room. You cn even
take the thermostat from room to room if you want.

"Andy Hall" wrote in message
...
On 2006-08-12 23:43:12 +0100, "Andrew Haylett" said:

Andrew Haylett wrote:
I'm having a new CH/HW system installed from scratch (to replace a
somewhat antique, expensive and broken warm air/gravity system). Our
chosen plumber has recommended:

Vaillant Ecotec 630 condensing boiler
Santon Premier Plus unvented pressurized cylinder
15 radiators
for a 5-bed house.

Wow, thanks for all the help. I'm a CH neophyte so all information is
helpful. A few (quite a few) follow-up questions to help my learning
experience.

Mains pressure. Yes, there are some concerns about that. When the
plumber first measured the flow rate at a tap it was about 15l/min.
They replaced the stopcock at the entry point (it was locked solid) and
maybe they fiddled with something, but he said he can now measure
20l/min, which he professes to be adequate.

It is if you just want to run one shower at a time or fill one bath - not
if you want to do more than this.

Also, it would be a good idea to check this at peak water usage times and
the times that you are likely to want to shower or bath.

What he wants to do is run
22mm from the entry point (currently 15mm) all the way up to the boiler
to improve the flow rate/pressure.

This may well improve the flow rate depending on the supply.

(The boiler is to be on the first
floor, in the airing cupboard.) Is that a helpful thing to do, given
that the rest of the system is 15mm which will presumably limit the
flow rate at the tap?

It depends on the length of the runs. Unless they are particularly
long - i.e. one side of the house to the other - that should be OK for
showers. The bath plumbing may already be 22mm - it usually is if there
is a roof tank system originally.

What are the implications of the mains water pressure falling below a
certain level? Sub-standard performance at the taps/shower head, or
worse?

Substandard performance and variation in flow as other things are used. A
thermostatic valve on showers will maintain temperature reasonable well
unless there are gross changes in available flow.

Pressure equalisation valves should be used, or mixers with them
incorporated.

Location. He offered to put the boiler in the loft (makes the flue a
bit easier if mounted on the side wall). I demurred since it seemed we
weren't going to have much room for clothes in the airing cupboard
anyway due to the size of the cylinder, so might as well stick the
boiler there, and because we don't have a 'proper' loft ladder so I was
concerned about servicing access. But it has been suggested AIUI that
both the boiler and the cylinder could be put in the loft, with safety
advantages. I'll ask him about that.

You would have to check the construction in the loft if the cylinder is to
go up there. Should be OK if it goes in the position of an existing
storage tank but needs to be checked - it's a lot of weight if you have a
large cylinder. If the boiler goes up there, the area from the access
hatch to it must be boarded and there must be a safety rail around the
hatch.

Shower pumps. He didn't mention about getting rid of the one we have.
I guess I don't fully understand the regs. I thought as it was pumping
out of the cylinder then it would be OK - or does having a pressurized
system mean that the whole house effectively becomes an extension of
the mains?

In effect, yes. The pump would have to go.

Unvented/heat store. I think I understand how the latter works. I
guess it's a bit like a combi where the HW to the taps is heated on
demand, except that the heating is done via a pre-heated body of water,
right? How large is a typical thermal store compared with an unvented
cylinder? How common, relatively speaking, are the two types of
system? And are there any ease-of-installation issues either way?

A thermal store can be run at 75-80 degrees as opposed to the 60 degrees
of stored HW.

Can be as low as 60C.

The implication of that is that for an equivalent amount of HW production,
the thermal store cylinder can be 3/4 of the size of a storage cylinder.
However, there are additional plumbing components such as valves, pump and
a heat exchanger. By the time those are added, there is not really any
saving of space.

Some thermal stores/heat banks have the plate heat exchangers inside the
cylinder. Some can be sealed to 1 bar, like a CH system.

Also a thermal store needs some kind of header tank to supply the water in
the main part of the cylinder because this is vented.

Not if it is sealed. One 24 litres expansion vessel will act on the
cylinder, CH pipes and boiler. But you have the same explosion points of an
unvented cylinder, but the boiler and cylinder have independent relief valve
giving two blow-off points.

Either this can be a small tank in the loft, or if the cylinder goes in
the loft, there are thermal stores with the header tank integrated on the
top. Again by the time you add this, there is no space saving. On the
other hand, space may not be as critical in the loft.
If you want an airing cupboard, you can always put a small radiator in
there.

Could the Vaillant boiler already specced drive a vented system? I
guess the boiler just sees an indirect system either way, whether
heating a pressurized body of water or a thermal store.

If you use an indirect store, there are, in effect, three lots of water.

- The primary, which runs through the boiler, the heating circuit and a
coil in the cylinder. This can be sealed and pressurised or open vented
according to boiler requirements and preference. There are a lot of
advantages in going for sealed and no real disadvantages.

- The water in the store cylinder. This is open vented and is
circulated, on HW demand between store and heat exchanger. Having it
open vented gets around the regulatory requirements of a pressurised
cylinder.

- The HW being heated from the mains. With a thermal store, there is
again no large volume storage in this part either.

Safety/maintenance. That's obviously a concern with 6 people in the
house - but how prone are unvented systems to blow up? Do they have a
bad safety record (assuming appropriate maintenance)?

They are widely fitted in many countries outside the UK and do not have a
bad reputation or safety record.

Abroad they do. I read one case in the US where they think a nasty
neighbour broke into a house while they were on hols. He put a compression
cap on open vent relief pipe and by-passed the electric immersion stat. He
then switched it on. Many hours later while he was elsewhere - kaboom, the
side of the house gone.

I'll check with
the plumber about servicing costs.

He hasn't said anything about building control approval for an unvented
system. Whose job would this be?

He needs to have a particular training and certification to
install/service an unvented system. Ask him about that. Assuming he
does, then he can self certify the installation and there is no need for
other approvals.

TRV/room stat. I'll skirt clear of this debate. ;-)

There is no debate, it is just me explaining it the amateurs.

He's fitting TRVs
throughout, plus an RF room controller. Hopefully that will give us
enough flexibility. I haven't considered zoning - didn't even know
about it - but will ask anyway. I would *think* that TRVs will give
enough flexibility to save energy in lesser used areas, e.g. spare
room, utility room, etc.

You could get him to fit TRVs on all the radiators - even the one where
the room thermostat is going.

Just have a Grundfos Alpha pump when using a thermal store/heat bank. TRVs
all around, and no wall stat just a simple programmer.

If you fully open the TRV on the radiator where the room thermostat is
located, then that room becomes the "controlling" room. You cn even take
the thermostat from room to room if you want.

Until it gets lost down the back of the sofa with the rest of the remotes.

On 2006-08-13 11:01:15 +0100, "Doctor Drivel" said:


"Andy Hall" wrote in message ...
On 2006-08-12 23:43:12 +0100, "Andrew Haylett" said:

Andrew Haylett wrote:

Unvented/heat store. I think I understand how the latter works. I
guess it's a bit like a combi where the HW to the taps is heated on
demand, except that the heating is done via a pre-heated body of water,
right? How large is a typical thermal store compared with an unvented
cylinder? How common, relatively speaking, are the two types of
system? And are there any ease-of-installation issues either way?

A thermal store can be run at 75-80 degrees as opposed to the 60
degrees of stored HW.

Can be as low as 60C.

Becomes rather pointless then, because the cylinder would need to be
the same size as a HW cylinder, and the temperature of the HW produced
less than 60 degrees.



The implication of that is that for an equivalent amount of HW
production, the thermal store cylinder can be 3/4 of the size of a
storage cylinder. However, there are additional plumbing components
such as valves, pump and a heat exchanger. By the time those are
added, there is not really any saving of space.

Some thermal stores/heat banks have the plate heat exchangers inside
the cylinder. Some can be sealed to 1 bar, like a CH system.

Also a thermal store needs some kind of header tank to supply the water
in the main part of the cylinder because this is vented.

Not if it is sealed. One 24 litres expansion vessel will act on the
cylinder, CH pipes and boiler.

????

Why would one seal it? One of the main points is not to need to do that.





Safety/maintenance. That's obviously a concern with 6 people in the
house - but how prone are unvented systems to blow up? Do they have a
bad safety record (assuming appropriate maintenance)?

They are widely fitted in many countries outside the UK and do not have
a bad reputation or safety record.

Abroad they do. I read one case in the US where they think a nasty
neighbour broke into a house while they were on hols. He put a
compression cap on open vent relief pipe and by-passed the electric
immersion stat. He then switched it on. Many hours later while he was
elsewhere - kaboom, the side of the house gone.

Mmmm.........

Hardly a common occurence though, is it?

"Andy Hall" wrote in message
...
On 2006-08-13 11:01:15 +0100, "Doctor Drivel" said:


"Andy Hall" wrote in message
...
On 2006-08-12 23:43:12 +0100, "Andrew Haylett" said:

Andrew Haylett wrote:

Unvented/heat store. I think I understand how the latter works. I
guess it's a bit like a combi where the HW to the taps is heated on
demand, except that the heating is done via a pre-heated body of water,
right? How large is a typical thermal store compared with an unvented
cylinder? How common, relatively speaking, are the two types of
system? And are there any ease-of-installation issues either way?

A thermal store can be run at 75-80 degrees as opposed to the 60 degrees
of stored HW.

Can be as low as 60C.

Becomes rather pointless then, because the cylinder would need to be the
same size as a HW cylinder, and the temperature of the HW produced less
than 60 degrees.

Using a double pass Danfoss plate heat exchanger 50-55C can be obtained at
the taps.

The implication of that is that for an equivalent amount of HW
production, the thermal store cylinder can be 3/4 of the size of a
storage cylinder. However, there are additional plumbing components such
as valves, pump and a heat exchanger. By the time those are added,
there is not really any saving of space.

Some thermal stores/heat banks have the plate heat exchangers inside the
cylinder. Some can be sealed to 1 bar, like a CH system.

Also a thermal store needs some kind of header tank to supply the water
in the main part of the cylinder because this is vented.

Not if it is sealed. One 24 litres expansion vessel will act on the
cylinder, CH pipes and boiler.

????

Why would one seal it? One of the main points is not to need to do that.

Another option. All he system, boiler CH pipes and cylinder are sealed. It
virtually eliminates any sludging.

Safety/maintenance. That's obviously a concern with 6 people in the
house - but how prone are unvented systems to blow up? Do they have a
bad safety record (assuming appropriate maintenance)?

They are widely fitted in many countries outside the UK and do not have
a bad reputation or safety record.

Abroad they do. I read one case in the US where they think a nasty
neighbour broke into a house while they were on hols. He put a
compression cap on open vent relief pipe and by-passed the electric
immersion stat. He then switched it on. Many hours later while he was
elsewhere - kaboom, the side of the house gone.

Mmmm.........

Hardly a common occurence though, is it?

Easy to do Matt.

In article ews.net,
Doctor Drivel wrote:
They are widely fitted in many countries outside the UK and do not
have a bad reputation or safety record.

Abroad they do. I read one case in the US where they think a nasty
neighbour broke into a house while they were on hols. He put a
compression cap on open vent relief pipe and by-passed the electric
immersion stat. He then switched it on. Many hours later while he was
elsewhere - kaboom, the side of the house gone.

And that's the fault of the device?

Hint. Any water heater of any type can be made to explode if tampered with
in the intention of making it do so.

--
*Change is inevitable, except from a vending machine.

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ews.net,
Doctor Drivel wrote:
They are widely fitted in many countries outside the UK and do not
have a bad reputation or safety record.

Abroad they do. I read one case in the US where they think a nasty
neighbour broke into a house while they were on hols. He put a
compression cap on open vent relief pipe and by-passed the electric
immersion stat. He then switched it on. Many hours later while he was
elsewhere - kaboom, the side of the house gone.

And that's the fault of the device?

If you think so. Please eff off as you are stupid.

Andy Hall wrote:

You could get him to fit TRVs on all the radiators - [...]

I wonder what became of the system you were working on a few years ago
with the individually addressable Sauter valve heads - as mentioned in
this article?

http://groups.google.com/group/uk.d-...e=source&hl=en

ISTR you mentioning commercial potential and patentable features in
later postings, but don't recall hearing anything since. Is is on the
market yet... ?

--
Andy

"Andy Wade" wrote in message
...
Andy Hall wrote:

You could get him to fit TRVs on all the radiators - [...]

I wonder what became of the system you were working on a few years ago
with the individually addressable Sauter valve heads - as mentioned in
this article?

http://groups.google.com/group/uk.d-...e=source&hl=en

ISTR you mentioning commercial potential and patentable features in later
postings, but don't recall hearing anything since. Is is on the market
yet... ?

He has a high pressure cylinder working low pressure. best he fits an
accumulator to get the mains water pressure/flow up to scratch and convert
the cylinder into a heat bank.

On 2006-08-13 11:48:56 +0100, Andy Wade said:

Andy Hall wrote:

You could get him to fit TRVs on all the radiators - [...]

I wonder what became of the system you were working on a few years ago
with the individually addressable Sauter valve heads - as mentioned in
this article?

http://groups.google.com/group/uk.d-...e=source&hl=en

ISTR you mentioning commercial potential and patentable features in
later postings, but don't recall hearing anything since. Is is on the
market yet... ?

Still in development. Tuit shortage.

The radiator control and data logging is effective, the main part is
coming up with a suitable front end interface.

Andy Hall wrote:

Tuit shortage.

A familiar state of affairs.

The radiator control and data logging is effective, the main part is
coming up with a suitable front end interface.

Announcements awaited with interest...
--
Andy

On 12 Aug 2006 15:43:12 -0700 someone who may be "Andrew Haylett"
wrote this:-

Unvented/heat store. I think I understand how the latter works. I
guess it's a bit like a combi where the HW to the taps is heated on
demand, except that the heating is done via a pre-heated body of water,
right?

Right. Think of it as a bit like a siege engine. One slowly winds
the mechanism up, it being impossible to wind the mechanism up
rapidly. Then all the energy is released in one go and the rock
shoots off at a far higher speed than one could throw it.

The store stores energy at the maximum rate that the boiler can
provide, but can release it more quickly.

How large is a typical thermal store compared with an unvented
cylinder?

The sizes are given on the links people provided. The answer is that
it depends.

How common, relatively speaking, are the two types of system?

Plumbers go by fashion. The fashion for some time has been unvented
systems, which have the additional advantage of a nice little earner
every year. Thermal stores are also somewhat newer and so news of
them has not penetrated everywhere.

And are there any ease-of-installation issues either way?

It depends. Generally the thermal store has slight advantages.



--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

Andrew Haylett wrote:
I'm having a new CH/HW system installed from scratch (to replace a
somewhat antique, expensive and broken warm air/gravity system). Our
chosen plumber has recommended:

Vaillant Ecotec 630 condensing boiler
Santon Premier Plus unvented pressurized cylinder
15 radiators
for a 5-bed house.

Wow, thanks for all the help. I'm a CH neophyte so all information is
helpful. A few (quite a few) follow-up questions to help my learning
experience.

Mains pressure. Yes, there are some concerns about that. When the
plumber first measured the flow rate at a tap it was about 15l/min.
They replaced the stopcock at the entry point (it was locked solid) and
maybe they fiddled with something, but he said he can now measure
20l/min, which he professes to be adequate. What he wants to do is run
22mm from the entry point (currently 15mm) all the way up to the boiler
to improve the flow rate/pressure. (The boiler is to be on the first
floor, in the airing cupboard.) Is that a helpful thing to do, given
that the rest of the system is 15mm which will presumably limit the
flow rate at the tap?

What are the implications of the mains water pressure falling below a
certain level? Sub-standard performance at the taps/shower head, or
worse?

Location. He offered to put the boiler in the loft (makes the flue a
bit easier if mounted on the side wall). I demurred since it seemed we
weren't going to have much room for clothes in the airing cupboard
anyway due to the size of the cylinder, so might as well stick the
boiler there, and because we don't have a 'proper' loft ladder so I was
concerned about servicing access. But it has been suggested AIUI that
both the boiler and the cylinder could be put in the loft, with safety
advantages. I'll ask him about that.

Shower pumps. He didn't mention about getting rid of the one we have.
I guess I don't fully understand the regs. I thought as it was pumping
out of the cylinder then it would be OK - or does having a pressurized
system mean that the whole house effectively becomes an extension of
the mains?

Unvented/heat store. I think I understand how the latter works. I
guess it's a bit like a combi where the HW to the taps is heated on
demand, except that the heating is done via a pre-heated body of water,
right? How large is a typical thermal store compared with an unvented
cylinder? How common, relatively speaking, are the two types of
system? And are there any ease-of-installation issues either way?

Could the Vaillant boiler already specced drive a vented system? I
guess the boiler just sees an indirect system either way, whether
heating a pressurized body of water or a thermal store.

Safety/maintenance. That's obviously a concern with 6 people in the
house - but how prone are unvented systems to blow up? Do they have a
bad safety record (assuming appropriate maintenance)? I'll check with
the plumber about servicing costs.

He hasn't said anything about building control approval for an unvented
system. Whose job would this be?

TRV/room stat. I'll skirt clear of this debate. ;-) He's fitting TRVs
throughout, plus an RF room controller. Hopefully that will give us
enough flexibility. I haven't considered zoning - didn't even know
about it - but will ask anyway. I would *think* that TRVs will give
enough flexibility to save energy in lesser used areas, e.g. spare
room, utility room, etc.

many thanks again,
Andrew.

In article om,
Andrew Haylett wrote:
TRV/room stat. I'll skirt clear of this debate. ;-) He's fitting TRVs
throughout, plus an RF room controller. Hopefully that will give us
enough flexibility. I haven't considered zoning - didn't even know
about it - but will ask anyway. I would *think* that TRVs will give
enough flexibility to save energy in lesser used areas, e.g. spare
room, utility room, etc.

If you balance up the system carefully with all the TRVs fully open so
you're relying on the main thermostat in the living area set to the
maximum you want, the TRVs will then take care of other rooms getting too
hot and wasting energy - but will still cool down to the lower
temperatures that you may programme in. It can work very well.

--
*A bartender is just a pharmacist with a limited inventory *

Dave Plowman London SW
To e-mail, change noise into sound.

On Fri, 11 Aug 2006 14:59:02 -0700, Andrew Haylett wrote:

I'm having a new CH/HW system installed from scratch (to replace a
somewhat antique, expensive and broken warm air/gravity system). Our
chosen plumber has recommended:

Vaillant Ecotec 630 condensing boiler
Santon Premier Plus unvented pressurized cylinder
15 radiators
for a 5-bed house.

He seems to be competent, but any comments would be appreciated. Is
mains pressure HW the way to go? (We already have a CW tank in the
loft, which would go.)

I am particularly interested in the safety and servicing requirements
of unvented systems.
http://www.gasapplianceguide.co.uk/M...er_Systems.htm
gives warnings, but is it partisan?

We already have a shower pump fitted in one of the bathrooms. Is this
permitted under the bye-law that prevents pumping from mains pressure
systems, or does that only apply to combi systems?


I think you might do well to read the BoilerChoice FAQ.

I have no strong preference for or against unvented cylinders.
They are not liked on this newsgroup because the regulations require the
use of a qualified installer and a notification to building control (the
latter is not relevant because installing a vented cylinder is also a
notifiable activity).

However, I acknowledge my bias as I do hold a G3 card (the unvented HW
storage qualification).

A properly installed mains pressure HW system (whether unvented, heat
bank or thermal store) will make the use of a pump both illegal and
unnecessary. Not all properties are suitable for mains pressure
installations.

HTH

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

"Ed Sirett" wrote in message
news
On Fri, 11 Aug 2006 14:59:02 -0700, Andrew Haylett wrote:

I'm having a new CH/HW system installed from scratch (to replace a
somewhat antique, expensive and broken warm air/gravity system). Our
chosen plumber has recommended:

Vaillant Ecotec 630 condensing boiler
Santon Premier Plus unvented pressurized cylinder
15 radiators
for a 5-bed house.

He seems to be competent, but any comments would be appreciated. Is
mains pressure HW the way to go? (We already have a CW tank in the
loft, which would go.)

I am particularly interested in the safety and servicing requirements
of unvented systems.
http://www.gasapplianceguide.co.uk/M...er_Systems.htm
gives warnings, but is it partisan?

We already have a shower pump fitted in one of the bathrooms. Is this
permitted under the bye-law that prevents pumping from mains pressure
systems, or does that only apply to combi systems?


I think you might do well to read the BoilerChoice FAQ.

It is about 20 years out of date.

I have no strong preference for or against unvented cylinders.
They are not liked on this newsgroup because the regulations require the
use of a qualified installer and a notification to building control (the
latter is not relevant because installing a vented cylinder is also a
notifiable activity).

You forgot the annual service charge. That precludes them full stop.

However, I acknowledge my bias as I do hold a G3 card (the unvented HW
storage qualification).

A properly installed mains pressure HW system (whether unvented, heat
bank or thermal store) will make the use of a pump both illegal and
unnecessary. Not all properties are suitable for mains pressure
installations.

They are if an accumulator is fitted. See my post on how to make one up.

"Andrew Haylett" wrote in message
ps.com...
I'm having a new CH/HW system installed from scratch (to replace a
somewhat antique, expensive and broken warm air/gravity system). Our
chosen plumber has recommended:

Vaillant Ecotec 630 condensing boiler
Santon Premier Plus unvented pressurized cylinder
15 radiators
for a 5-bed house.

He seems to be competent, but any comments would be appreciated. Is
mains pressure HW the way to go? (We already have a CW tank in the
loft, which would go.)

I am particularly interested in the safety and servicing requirements
of unvented systems.
http://www.gasapplianceguide.co.uk/M...er_Systems.htm
gives warnings, but is it partisan?

We already have a shower pump fitted in one of the bathrooms. Is this
permitted under the bye-law that prevents pumping from mains pressure
systems, or does that only apply to combi systems?

thanks,
Andrew.

Another approach is to have a Rinnai multi-point high flow water heater
(which can also be fitted outside) and a small CH boiler. No space taken up
and high flow at mains pressure. Cost is about the same, or maybe cheaper
than a boiler/unvented cylinder/heat bank. Both can go in the loft as well.
The downside is the Rinnai may need a service as does the unvented cylinder.
One big plus is that you never run out of hot water and can run multi-jet
Tower Showers from it and "never" run out of hot water. No standing heat
losses either.