I have an unvented Vaillant condensing boiler which is regularly losing
pressure - I guestimate te loss to be of the order of about 3 pints per
week judging by the length of time I have to open the valve on the
filling loop. (The gauge on the boiler falls to zero and said boiler
starts to make strangulated noises...)

This has been happening all summer, ie with the CH switched off. I
can't see any leaks anywhere, and the tundish by the pressure relief
valve is dry; but logic tells me the water must be going somewhere, and
surely at this rate ought to be detectable. Where's it going?!

Thanks
David

On Fri, 08 Sep 2006 16:30:44 +0000, Lobster wrote:

I have an unvented Vaillant condensing boiler which is regularly losing
pressure - I guestimate te loss to be of the order of about 3 pints per
week judging by the length of time I have to open the valve on the
filling loop. (The gauge on the boiler falls to zero and said boiler
starts to make strangulated noises...)

This has been happening all summer, ie with the CH switched off. I
can't see any leaks anywhere, and the tundish by the pressure relief
valve is dry; but logic tells me the water must be going somewhere, and
surely at this rate ought to be detectable. Where's it going?!

Have a read of the SealedCH FAQ and then see what else you need to know.



--
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:
On Fri, 08 Sep 2006 16:30:44 +0000, Lobster wrote:

I have an unvented Vaillant condensing boiler which is regularly losing
pressure - I guestimate te loss to be of the order of about 3 pints per
week judging by the length of time I have to open the valve on the
filling loop. (The gauge on the boiler falls to zero and said boiler
starts to make strangulated noises...)

This has been happening all summer, ie with the CH switched off. I
can't see any leaks anywhere, and the tundish by the pressure relief
valve is dry; but logic tells me the water must be going somewhere, and
surely at this rate ought to be detectable. Where's it going?!

Have a read of the SealedCH FAQ and then see what else you need to know.

Already have actually! Decided it couldn't be the expansion vessel
because the pressure only drops, it doesn't cycle (have I understood
that correctly?); and the pressure-relief valve seems OK as I said. And
I'd have thought I'd notice the effects of the volume of water which is
apparently vanishing... so I'm stumped!

David

On Fri, 08 Sep 2006 20:50:05 +0000, Lobster wrote:

Ed Sirett wrote:
On Fri, 08 Sep 2006 16:30:44 +0000, Lobster wrote:

I have an unvented Vaillant condensing boiler which is regularly losing
pressure - I guestimate te loss to be of the order of about 3 pints per
week judging by the length of time I have to open the valve on the
filling loop. (The gauge on the boiler falls to zero and said boiler
starts to make strangulated noises...)

This has been happening all summer, ie with the CH switched off. I
can't see any leaks anywhere, and the tundish by the pressure relief
valve is dry; but logic tells me the water must be going somewhere, and
surely at this rate ought to be detectable. Where's it going?!

Have a read of the SealedCH FAQ and then see what else you need to know.

Already have actually! Decided it couldn't be the expansion vessel
because the pressure only drops, it doesn't cycle (have I understood
that correctly?); and the pressure-relief valve seems OK as I said. And
I'd have thought I'd notice the effects of the volume of water which is
apparently vanishing... so I'm stumped!

Have a really good look all around the pipe work.
Is there any place where it could go unnoticed?
You could probably get the leak to stop with leak sealer.
It could be in the boiler itself and evaporating with the heat.


--
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, 08 Sep 2006 20:50:05 +0000, Lobster wrote:

Ed Sirett wrote:
On Fri, 08 Sep 2006 16:30:44 +0000, Lobster wrote:

I have an unvented Vaillant condensing boiler which is regularly losing
pressure - I guestimate te loss to be of the order of about 3 pints per
week judging by the length of time I have to open the valve on the
filling loop. (The gauge on the boiler falls to zero and said boiler
starts to make strangulated noises...)

This has been happening all summer, ie with the CH switched off. I
can't see any leaks anywhere, and the tundish by the pressure relief
valve is dry; but logic tells me the water must be going somewhere, and
surely at this rate ought to be detectable. Where's it going?!

Have a read of the SealedCH FAQ and then see what else you need to know.

Already have actually! Decided it couldn't be the expansion vessel
because the pressure only drops, it doesn't cycle (have I understood
that correctly?); and the pressure-relief valve seems OK as I said. And
I'd have thought I'd notice the effects of the volume of water which is
apparently vanishing... so I'm stumped!

Have a really good look all around the pipe work.
Is there any place where it could go unnoticed?
You could probably get the leak to stop with leak sealer.
It could be in the boiler itself and evaporating with the heat.


my boiler did this and it turned out to be the thermostatic valves. 3 out of
4 leaked around the top under the thermostat control.
Dave

Ed Sirett wrote:
On Fri, 08 Sep 2006 20:50:05 +0000, Lobster wrote:

On Fri, 08 Sep 2006 16:30:44 +0000, Lobster wrote:

I have an unvented Vaillant condensing boiler which is regularly losing
pressure - I guestimate te loss to be of the order of about 3 pints per
week judging by the length of time I have to open the valve on the
filling loop. (The gauge on the boiler falls to zero and said boiler
starts to make strangulated noises...)

This has been happening all summer, ie with the CH switched off. I
can't see any leaks anywhere, and the tundish by the pressure relief
valve is dry; but logic tells me the water must be going somewhere, and
surely at this rate ought to be detectable. Where's it going?!

Already have actually! Decided it couldn't be the expansion vessel
because the pressure only drops, it doesn't cycle (have I understood
that correctly?); and the pressure-relief valve seems OK as I said. And
I'd have thought I'd notice the effects of the volume of water which is
apparently vanishing... so I'm stumped!

Have a really good look all around the pipe work.
Is there any place where it could go unnoticed?

Thanks Ed. Well, I thought I had had a good look... the pipework twixt
boiler and HW tank does pass under the upstairs floor for several
metres, and I haven't pulled up carpets to inspect that; but you'd think
that level of leak would have manifested itself, wouldn't you?

You could probably get the leak to stop with leak sealer.

Mm, maybe that's where I'm headed; seems a bit of a bodge solution though?

It could be in the boiler itself and evaporating with the heat.

Because my problem is not tied to the central heating being on?
Presumably I just need to be looking at the boiler/HW tank/intermediate
pipes, is that right?

David

On Sat, 09 Sep 2006 21:03:07 +0000, Lobster wrote:

Ed Sirett wrote:
On Fri, 08 Sep 2006 20:50:05 +0000, Lobster wrote:

On Fri, 08 Sep 2006 16:30:44 +0000, Lobster wrote:

I have an unvented Vaillant condensing boiler which is regularly losing
pressure - I guestimate te loss to be of the order of about 3 pints per
week judging by the length of time I have to open the valve on the
filling loop. (The gauge on the boiler falls to zero and said boiler
starts to make strangulated noises...)

This has been happening all summer, ie with the CH switched off. I
can't see any leaks anywhere, and the tundish by the pressure relief
valve is dry; but logic tells me the water must be going somewhere, and
surely at this rate ought to be detectable. Where's it going?!

Already have actually! Decided it couldn't be the expansion vessel
because the pressure only drops, it doesn't cycle (have I understood
that correctly?); and the pressure-relief valve seems OK as I said. And
I'd have thought I'd notice the effects of the volume of water which is
apparently vanishing... so I'm stumped!

Have a really good look all around the pipe work.
Is there any place where it could go unnoticed?

Thanks Ed. Well, I thought I had had a good look... the pipework twixt
boiler and HW tank does pass under the upstairs floor for several
metres, and I haven't pulled up carpets to inspect that; but you'd think
that level of leak would have manifested itself, wouldn't you?

You could probably get the leak to stop with leak sealer.

Mm, maybe that's where I'm headed; seems a bit of a bodge solution though?

It could be in the boiler itself and evaporating with the heat.

Because my problem is not tied to the central heating being on?
Presumably I just need to be looking at the boiler/HW tank/intermediate
pipes, is that right?

No. All the primary pipework ( that includes the rads) are under
pressure, although some types of leakage happen only when the pipes are
warmed.

IME you can loose a litre or two a week and not be flooded out, look
carefully for damp patches. Assuming its not the relief valve itself then
the most likely places a
1) The radiator valves.
2) The boiler

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:
On Sat, 09 Sep 2006 21:03:07 +0000, Lobster wrote:

Ed Sirett wrote:
On Fri, 08 Sep 2006 20:50:05 +0000, Lobster wrote:

On Fri, 08 Sep 2006 16:30:44 +0000, Lobster wrote:

I have an unvented Vaillant condensing boiler which is regularly losing
pressure - I guestimate te loss to be of the order of about 3 pints per
week judging by the length of time I have to open the valve on the
filling loop. (The gauge on the boiler falls to zero and said boiler
starts to make strangulated noises...)

This has been happening all summer, ie with the CH switched off. I
can't see any leaks anywhere, and the tundish by the pressure relief
valve is dry; but logic tells me the water must be going somewhere, and
surely at this rate ought to be detectable. Where's it going?!
Already have actually! Decided it couldn't be the expansion vessel
because the pressure only drops, it doesn't cycle (have I understood
that correctly?); and the pressure-relief valve seems OK as I said. And
I'd have thought I'd notice the effects of the volume of water which is
apparently vanishing... so I'm stumped!

Have a really good look all around the pipe work.
Is there any place where it could go unnoticed?
Thanks Ed. Well, I thought I had had a good look... the pipework twixt
boiler and HW tank does pass under the upstairs floor for several
metres, and I haven't pulled up carpets to inspect that; but you'd think
that level of leak would have manifested itself, wouldn't you?

You could probably get the leak to stop with leak sealer.
Mm, maybe that's where I'm headed; seems a bit of a bodge solution though?

It could be in the boiler itself and evaporating with the heat.
Because my problem is not tied to the central heating being on?
Presumably I just need to be looking at the boiler/HW tank/intermediate
pipes, is that right?

No. All the primary pipework ( that includes the rads) are under
pressure, although some types of leakage happen only when the pipes are
warmed.

Thanks again Ed. Armed with that knowledge I'll have (yet) another good
look round.

IME you can loose a litre or two a week and not be flooded out, look
carefully for damp patches. Assuming its not the relief valve itself then
the most likely places a
1) The radiator valves.
2) The boiler

Cheers
David