The pressure in my volkera compact, about 7 years old, keeps dropping. I have replaced the expansion vessel whos diaphragm had gone, still drops. Not leaking from the pressure relief valve or the air release valve in the boiler and no signs of water in the boiler. I have tried isolating the boiler from the rads by shutting the isolating valves and it still drops, so assuming the valves are truly shut then leak must be in the boiler somewhere. Can it leak from the main heat exchanger into the condensate? If so how can I tell before I call in a gas engineer?

On Wednesday, 17 July 2019 10:39:59 UTC+1, Steve Jones wrote:

The pressure in my volkera compact, about 7 years old, keeps dropping. I have replaced the expansion vessel whos diaphragm had gone, still drops. Not leaking from the pressure relief valve or the air release valve in the boiler and no signs of water in the boiler. I have tried isolating the boiler from the rads by shutting the isolating valves and it still drops, so assuming the valves are truly shut then leak must be in the boiler somewhere. Can it leak from the main heat exchanger into the condensate? If so how can I tell before I call in a gas engineer?

So you have a leak somewhere. Iso valves don't always iso. Anything can leak. Sounds like you need a good plumber rather than gas engineer. A pressure gauge on the other side of the iso valves would help narrow things down. You can also put fluorescein in the water & use uv to help see where it's leaking. I'm not a plumber, there may be better suggestions from others.


NT

On 17/07/2019 10:39, Steve Jones wrote:

The pressure in my volkera compact, about 7 years old, keeps
dropping. I have replaced the expansion vessel whos diaphragm had
gone, still drops. Not leaking from the pressure relief valve or the
air release valve in the boiler and no signs of water in the boiler.
I have tried isolating the boiler from the rads by shutting the
isolating valves and it still drops, so assuming the valves are truly
shut then leak must be in the boiler somewhere. Can it leak from the
main heat exchanger into the condensate?

Yup, I have exactly the same issue with my boiler. Having checked all
the possible pipework leaks, I realised it was in the boiler itself.

If so how can I tell before
I call in a gas engineer?

Turn off the boiler. Top up the pressure to ~1 bar if required. Isolate
the CH flow and return. Now remove and empty the condensate trap[1], and
replace. Leave for an hour or two and see if pressure has dropped. Check
the condensate trap again. If there is a leak in the main HX, then there
will be water in there (you may even see an occasional drip from the
trap mounting point.

[1] Note the water in this should be clean and clear with little
colouration or debris. If it has iron oxide or rust coloured staining,
then its a good indication that primary CH water has been getting
through to the trap - something it ought not be able to do.

--
Cheers,

John.

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

on 17/07/2019, John Rumm supposed :
Turn off the boiler. Top up the pressure to ~1 bar if required. Isolate the
CH flow and return. Now remove and empty the condensate trap[1], and replace.
Leave for an hour or two and see if pressure has dropped. Check the
condensate trap again. If there is a leak in the main HX, then there will be
water in there (you may even see an occasional drip from the trap mounting
point.

Isolator valves don't usually completely isolate, they will still pass
some water.

Last resort to trace the leak, is to drain the water and pump the
system up with air pressure. Air will escape much more easily that
water, so more volume and you will hear an hiss.

On Wed, 17 Jul 2019 15:11:40 +0100, Harry Bloomfield wrote:

Isolator valves don't usually completely isolate, they will still pass
some water.

Gate valves yes, ball valves are much more reliable. I think I've got
rid of any gate valves in this place...

--
Cheers
Dave.

On 17/07/2019 15:11, Harry Bloomfield wrote:
on 17/07/2019, John Rumm supposed :
Turn off the boiler. Top up the pressure to ~1 bar if required.
Isolate the CH flow and return. Now remove and empty the condensate
trap[1], and replace. Leave for an hour or two and see if pressure has
dropped. Check the condensate trap again. If there is a leak in the
main HX, then there will be water in there (you may even see an
occasional drip from the trap mounting point.

Isolator valves don't usually completely isolate, they will still pass
some water.

It does not really matter - if you empty the trap and the boiler is not
running, it should stay empty.


--
Cheers,

John.

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

On Thursday, 18 July 2019 00:24:01 UTC+1, John Rumm wrote:
On 17/07/2019 15:11, Harry Bloomfield wrote:
on 17/07/2019, John Rumm supposed :
Turn off the boiler. Top up the pressure to ~1 bar if required.
Isolate the CH flow and return. Now remove and empty the condensate
trap[1], and replace. Leave for an hour or two and see if pressure has
dropped. Check the condensate trap again. If there is a leak in the
main HX, then there will be water in there (you may even see an
occasional drip from the trap mounting point.

Isolator valves don't usually completely isolate, they will still pass
some water.

It does not really matter - if you empty the trap and the boiler is not
running, it should stay empty.


--
Cheers,

John.

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

Thanks, will try trap test this weekend

On 18/07/2019 11:31, Steve Jones wrote:
On Thursday, 18 July 2019 00:24:01 UTC+1, John Rumm wrote:
On 17/07/2019 15:11, Harry Bloomfield wrote:
on 17/07/2019, John Rumm supposed :
Turn off the boiler. Top up the pressure to ~1 bar if required.
Isolate the CH flow and return. Now remove and empty the condensate
trap[1], and replace. Leave for an hour or two and see if pressure has
dropped. Check the condensate trap again. If there is a leak in the
main HX, then there will be water in there (you may even see an
occasional drip from the trap mounting point.

Isolator valves don't usually completely isolate, they will still pass
some water.

It does not really matter - if you empty the trap and the boiler is not
running, it should stay empty.


Thanks, will try trap test this weekend

If you do the test and the trap does not refill, remember to refill it
manually, since its not good to run the boiler with an empty trap since
there is a slight risk it could allow combustion products back into the
room via the empty trap.


--
Cheers,

John.

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

On 17/07/2019 10:39, Steve Jones wrote:
The pressure in my volkera compact, about 7 years old, keeps dropping.

Having same bother with same boiler and the condensate trap has been
clogged a couple of times with some crap that looks like sand.

Could the sandy crap be forming in the system somewhere,

Or could somehow the crap be being drawn into the condensate trap from
the drain, is that even possible?

It happens that R D S formulated :
Having same bother with same boiler and the condensate trap has been clogged
a couple of times with some crap that looks like sand.

Likely airbourne sand from the Sahara. It just dirt drawn into the
combustion chamber, washed down and out by the condensate. Thats why
the trap is supposed to be checked and cleaned out as part of the
service.