expansion vessel in combi boiler not coping..
 

The central heating system I installed in my house has worked fine for
5 years or so. Then, last sumer, I installed a larger radiator in one
of the rooms (a double rad, measuring 6' x 18" approx. Since then, the
expansion vessel in the boiler has stopped coping with the expansion
of the heated water. I think the new rad is the problem, beccause if I
isolate that rad, the boiler works ok, and water pressure is
sustained. If I un-isolate that rad, and fill the system to 1.25 bar,
it blows water out of the relief valve as oon as it gets hot, and then
the guage on the boiler soon reads 0 bar, and the boiler starts making
a sort of moaning noise, kinda like an incoming 18" shell from a
battleship, just before it hits you. (At least that's wht my vivid
imagination cooks up). As soon as you increase the pressure ot above 1
bar, the noise stops.

I guess the solution is (a) to switch back to a smaller rad, or (b) to
fit a larger expansion vessel. Do you agree?

Does anyone know if a larger expansion vessel can be fitted to a
Britony 80 combi boiler, and if so, how much one costs, and is it an
easy job to fit it? I'm a bit woried by the manual which says the
expansion vessel is part of the boiler's chassis.

Thank you,
Jake

Dave£ wrote:

I guess the solution is (a) to switch back to a smaller rad, or (b) to
fit a larger expansion vessel. Do you agree?

How about (c) fit an additional expansion vessel?

Assuming your current one is working fine and has not lost air pressure,
it sounds like the volume of water in your system with the bigger rad is
too great for the size of vessel built into the boiler. The simple
solution would be to fit another one somewhere else on the system. They
are not that expensive as a stand alone item.


--
Cheers,

John.

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or (b) to fit a larger expansion vessel. Do you agree?

Yes, although there is no need to remove the old one. Just stick an
additional one on in a convenient location.

Does anyone know if a larger expansion vessel can be fitted to a
Britony 80 combi boiler, and if so, how much one costs, and is it an
easy job to fit it? I'm a bit woried by the manual which says the
expansion vessel is part of the boiler's chassis.

Leave the built in one alone. An additional expansion vessel will cost a few
tens of pounds and is easy to fit. Indeed, I would regard it as a
particularly suitable project for someone interested in learning a bit about
plumbing. It can be installed just about anywhere on the system, but
preferably not zoned off.

Christian.

On Fri, 19 Nov 2004 15:47:58 -0000, "Christian McArdle"
wrote:

or (b) to fit a larger expansion vessel. Do you agree?

Yes, although there is no need to remove the old one. Just stick an
additional one on in a convenient location.

Does anyone know if a larger expansion vessel can be fitted to a
Britony 80 combi boiler, and if so, how much one costs, and is it an
easy job to fit it? I'm a bit woried by the manual which says the
expansion vessel is part of the boiler's chassis.

Leave the built in one alone. An additional expansion vessel will cost a few
tens of pounds and is easy to fit. Indeed, I would regard it as a
particularly suitable project for someone interested in learning a bit about
plumbing. It can be installed just about anywhere on the system, but
preferably not zoned off.

Christian.

Thanks John and Christian. It's good to learn that stand-alone
expansion vessels are available. I didn't know they existed before you
enlightened me. I'll try to source one.

Dave

..

On Fri, 19 Nov 2004 10:48:17 +0000, Dave£ wrote:


The central heating system I installed in my house has worked fine for
5 years or so. Then, last sumer, I installed a larger radiator in one
of the rooms (a double rad, measuring 6' x 18" approx. Since then, the
expansion vessel in the boiler has stopped coping with the expansion
of the heated water. I think the new rad is the problem, beccause if I
isolate that rad, the boiler works ok, and water pressure is
sustained. If I un-isolate that rad, and fill the system to 1.25 bar,
it blows water out of the relief valve as oon as it gets hot, and then
the guage on the boiler soon reads 0 bar, and the boiler starts making
a sort of moaning noise, kinda like an incoming 18" shell from a
battleship, just before it hits you. (At least that's wht my vivid
imagination cooks up). As soon as you increase the pressure ot above 1
bar, the noise stops.

I guess the solution is (a) to switch back to a smaller rad, or (b) to
fit a larger expansion vessel. Do you agree?

Does anyone know if a larger expansion vessel can be fitted to a
Britony 80 combi boiler, and if so, how much one costs, and is it an
easy job to fit it? I'm a bit woried by the manual which says the
expansion vessel is part of the boiler's chassis.

See FAQ. I expect the existing unit has failed. Adding a new one elswhere
_may_ be the easiest course of action. Sub-£50 certinaly for all the bits
probably sub-£30.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at 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

Dave£ wrote:

Thanks John and Christian. It's good to learn that stand-alone
expansion vessels are available. I didn't know they existed before you
enlightened me. I'll try to source one.

Try:-

http://www.bes.ltd.uk/products/109.asp

The smallest is under 15 quid.



--
Cheers,

John.

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| Internode Ltd - http://www.internode.co.uk |
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\================================================= ================/

On Fri, 19 Nov 2004 20:12:07 +0000, John Rumm
wrote:

Dave£ wrote:

Thanks John and Christian. It's good to learn that stand-alone
expansion vessels are available. I didn't know they existed before you
enlightened me. I'll try to source one.

Try:-

http://www.bes.ltd.uk/products/109.asp

The smallest is under 15 quid.

Thanks John! All I need to do now is determine what size I need...

Dave

Dave£ wrote:


Thanks John! All I need to do now is determine what size I need...

Assuming that the first one in the boiler is working OK, then then
smallest will do since you are only "one radiators worth" of water over
what it can cope with.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Fri, 19 Nov 2004 23:28:01 +0000, John Rumm wrote:

Dave£ wrote:


Thanks John! All I need to do now is determine what size I need...

Assuming that the first one in the boiler is working OK, then then
smallest will do since you are only "one radiators worth" of water over
what it can cope with.

Assuming that the one in the boiler is dead or dying then the same size
again. Likely 10 litres (could get away with 8 for a small [1] system).


[1] I mean numbers of radiator == low volume of primary circuit.
--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at 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

Ed Sirett wrote:
On Fri, 19 Nov 2004 23:28:01 +0000, John Rumm wrote:


Dave£ wrote:



Thanks John! All I need to do now is determine what size I need...

Assuming that the first one in the boiler is working OK, then then
smallest will do since you are only "one radiators worth" of water over
what it can cope with.


Assuming that the one in the boiler is dead or dying then the same size
again. Likely 10 litres (could get away with 8 for a small [1] system).

Or even:
Assuming you don't know whether the one in the boiler is dead or alive,
go for one big enough to cope with the whole system, since too little
expansion room is a problem, whereas too much is not. ;-)



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
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