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  #11   Report Post  
Old March 9th 19, 11:19 PM posted to uk.d-i-y
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Posts: 22,076
Default Looking for a leak

On 09/03/2019 19:57, Roger Mills wrote:
On 09/03/2019 18:25, John Rumm wrote:

So far all the normal tricks don't seem to be doing it!

Short version:

There is a leak somewhere in my central heating system - its losing
pressure regularly, and needs topping up with at least a couple of
litres a day.

Longer version:

The pipework is of questionable vintage, but I am guessing 30+ years
old. Almost exclusively copper apart from about 3m of speedfit for one
particularly awkward pipe run. Largish S Plan+ system - unvented
cylinder and about 21 rads (split into separate upstairs and downstairs
zones).

The system was pretty good - only needing a small top up at most once or
twice a year. However over the last year its got worse. It got to the
point where it needed a top up every other week or so. So I carefully
checked around any areas where there have been changes in recent times.

I found one radiator tail in the downstairs loo where I had needed to do
a "live" pipework change and had used a cuprofit fitting that was
knocking about in the plumbing kit. That had a very slight indication of
a weep from around the base of the fitting. So I chopped it out and
re-did it properly. After that, no improvement or the rate of loss
seemed to get even worse! Even though there is definitely no evidence of
a leak in that location now.

So I checked the PRV drain pipe on the system boiler. That's not letting
by. Checked the drain point tap which is outside - again its dry.

Seems unlikely its the coil in the indirect cylinder since it is an
unvented cylinder, and the water pressure inside it is higher than that
of the CH primary - so if that leaked the CH would fill up!

So I had a careful look about. No indications of staining on the
ceilings, and it seems unlily one could lose that much water by
evaporation from the leak point. so I thought ground floor would be more
likely - there is loads of space in the under floor void where you could
lose water without it showing up anywhere.

However over the last few weeks I managed to get eyes on pretty much all
the GF pipework (sometimes indirectly by bribing second born to climb
through a hole in the floor and romp about in void and look for any
signs of leaks or damp, or corroded looking pipes etc). Got some more
boards up today and looked at the last two rad pipe runs. Again all ok.

Any bright ideas?


Do you have a means of isolating individual zones - in order to narrow
down the problem area? I'd be surprised if you didn't have strategically
located quarter turn valves for the purpose.


Alas, I did not install the original system (although I did install the
boiler, hot water tank, and did the zoning and controls).

I know I can easily add isolation for the flow side of each zone - just
after the two port valves. However I am not convinced that I can do the
return at a place that would allow segments to be isolated completely
from each other.

--
Cheers,

John.

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

  #13   Report Post  
Old March 9th 19, 11:24 PM posted to uk.d-i-y
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First recorded activity by DIYBanter: Jul 2006
Posts: 22,076
Default Looking for a leak

On 09/03/2019 21:49, David wrote:
On Saturday, 9 March 2019 18:25:13 UTC, John Rumm wrote:
There is a leak somewhere in my central heating system - its losing
pressure regularly, and needs topping up with at least a couple of
litres a day.

Any bright ideas?


I had a cracked heat exchanger. Because it was a condensing boiler, it happily drained all the leaked water down the condensate pipe.


Yup I did consider that, and was wondering how to test it without taking
the cover off the combustion chamber...

Could you see whether the boiler appears to be producing condensate even when it's powered off?

Alternatively, can you isolate the boiler and see whether its pressure decreases over time?


Yup, that would probably do it actually. If I take the front cover off
then I can see the internal mechanical pressure gauge (normally the one
you can see from outside is electronic and on the boiler's LCD).


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/
  #14   Report Post  
Old March 9th 19, 11:26 PM posted to uk.d-i-y
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First recorded activity by DIYBanter: Jul 2006
Posts: 22,076
Default Looking for a leak

On 09/03/2019 19:14, Thomas Prufer wrote:
On Sat, 9 Mar 2019 18:25:08 +0000, John Rumm
wrote:

Any bright ideas?


Fluorescein dye and a UV flashlight?


What type, and where would be a good place to get it (the dye that is, I
have the torch!)?


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/
  #15   Report Post  
Old March 10th 19, 08:55 AM posted to uk.d-i-y
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First recorded activity by DIYBanter: Sep 2012
Posts: 8,228
Default Looking for a leak

On Saturday, 9 March 2019 18:25:13 UTC, John Rumm wrote:
So far all the normal tricks don't seem to be doing it!

Short version:

There is a leak somewhere in my central heating system - its losing
pressure regularly, and needs topping up with at least a couple of
litres a day.

Longer version:

The pipework is of questionable vintage, but I am guessing 30+ years
old. Almost exclusively copper apart from about 3m of speedfit for one
particularly awkward pipe run. Largish S Plan+ system - unvented
cylinder and about 21 rads (split into separate upstairs and downstairs
zones).

The system was pretty good - only needing a small top up at most once or
twice a year. However over the last year its got worse. It got to the
point where it needed a top up every other week or so. So I carefully
checked around any areas where there have been changes in recent times.

I found one radiator tail in the downstairs loo where I had needed to do
a "live" pipework change and had used a cuprofit fitting that was
knocking about in the plumbing kit. That had a very slight indication of
a weep from around the base of the fitting. So I chopped it out and
re-did it properly. After that, no improvement or the rate of loss
seemed to get even worse! Even though there is definitely no evidence of
a leak in that location now.

So I checked the PRV drain pipe on the system boiler. That's not letting
by. Checked the drain point tap which is outside - again its dry.

Seems unlikely its the coil in the indirect cylinder since it is an
unvented cylinder, and the water pressure inside it is higher than that
of the CH primary - so if that leaked the CH would fill up!

So I had a careful look about. No indications of staining on the
ceilings, and it seems unlily one could lose that much water by
evaporation from the leak point. so I thought ground floor would be more
likely - there is loads of space in the under floor void where you could
lose water without it showing up anywhere.

However over the last few weeks I managed to get eyes on pretty much all
the GF pipework (sometimes indirectly by bribing second born to climb
through a hole in the floor and romp about in void and look for any
signs of leaks or damp, or corroded looking pipes etc). Got some more
boards up today and looked at the last two rad pipe runs. Again all ok.

Any bright ideas?


Leak on heat exchanger of boiler itself.
They can leak only when it's firing/hot.
Water evaporates so not necessarily any drips.


Tie plastic bags over PRV vents, it only leaks as water heats up.
And when it's topped up.

Does it lose water when not running?
(Clue to above)


  #17   Report Post  
Old March 10th 19, 09:59 AM posted to uk.d-i-y
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First recorded activity by DIYBanter: Aug 2006
Posts: 9,766
Default Looking for a leak

Also is there any way to isolate a zone?

I rremember in a friends house about ten years ago, I walked into an
upstairs room and said, it smells like fresh plumbing in here. IE I cannot
describe it, but there is a smell of dampness and something like a coppery
tinge to it.
There was a tiny pinhole in a pipe to the radiator there. It semmed to be
almost like steam. Weird, as I do not see how one can get a pin hole in a
pipe. Still that sort of problem has always put me off of central heating
since.
Brian

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This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Paul Welsh" wrote in message
...
On 09/03/2019 18:25, John Rumm wrote:

Any bright ideas?


I cut strips of kitchen paper and tie it around every possible leaking
joint.

I live in a hard water area so even if the water evaporates I get calcium
deposits after a few weeks or months, these can be felt by the paper going
slightly hard and discoloured.

Two litres sounds a lot. How do you measure it?



  #18   Report Post  
Old March 10th 19, 10:26 AM posted to uk.d-i-y
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First recorded activity by DIYBanter: Jan 2015
Posts: 9,601
Default Looking for a leak

On Sunday, 10 March 2019 08:29:20 UTC, Andrew Gabriel wrote:
On 09/03/2019 20:31, Richard wrote:
On 09/03/2019 20:04, tabbypurr wrote:
On Saturday, 9 March 2019 19:56:59 UTC, Roger MillsĀ* wrote:
On 09/03/2019 18:25, John Rumm wrote:

So far all the normal tricks don't seem to be doing it!

Short version:

There is a leak somewhere in my central heating system - its losing
pressure regularly, and needs topping up with at least a couple of
litres a day.

Do you have a means of isolating individual zones - in order to narrow
down the problem area? I'd be surprised if you didn't have strategically
located quarter turn valves for the purpose.

all of which have seized beyond all hope.


Your optimism is boundless


I installed full bore isolating lever valves for each section, in part
because I installed the system in stages over a year. By about 2 years
later, they were all seized on. These valves only work if exercised
regularly. The two that came with the boiler's system kit did seem to
last significantly longer, so it could be a quality issue.


I changed a pump on a 30-40 year old system and was shocked to discover that one of the ball valves to isolate the pump still worked. Of course the other one didn't.


NT
  #19   Report Post  
Old March 10th 19, 10:46 AM posted to uk.d-i-y
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First recorded activity by DIYBanter: Oct 2011
Posts: 1,131
Default Looking for a leak

"Brian Gaff" wrote in message ...

Also is there any way to isolate a zone?

I rremember in a friends house about ten years ago, I walked into an
upstairs room and said, it smells like fresh plumbing in here. IE I cannot
describe it, but there is a smell of dampness and something like a coppery
tinge to it.
There was a tiny pinhole in a pipe to the radiator there. It semmed to be
almost like steam. Weird, as I do not see how one can get a pin hole in a
pipe. Still that sort of problem has always put me off of central heating
since.
Brian


I once owned a flat (over one of my launderettes) where pin holes kept
appearing in 1/2" (not 15 mm) cold water pipes. Happened several times so
eventually we changed the pipes. Installed mid 1960's I suspect but could
have been as late as mid 1970's. It was a hard water area.

Andrew

  #20   Report Post  
Old March 10th 19, 11:27 AM posted to uk.d-i-y
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First recorded activity by DIYBanter: Apr 2009
Posts: 33,505
Default Looking for a leak

On 10/03/2019 08:29, Andrew Gabriel wrote:
On 09/03/2019 20:31, Richard wrote:
On 09/03/2019 20:04, wrote:
On Saturday, 9 March 2019 19:56:59 UTC, Roger MillsĀ* wrote:
On 09/03/2019 18:25, John Rumm wrote:

So far all the normal tricks don't seem to be doing it!

Short version:

There is a leak somewhere in my central heating system - its losing
pressure regularly, and needs topping up with at least a couple of
litres a day.

Do you have a means of isolating individual zones - in order to narrow
down the problem area? I'd be surprised if you didn't have
strategically
located quarter turn valves for the purpose.

all of which have seized beyond all hope.


Your optimism is boundless


I installed full bore isolating lever valves for each section, in part
because I installed the system in stages over a year. By about 2 years
later, they were all seized on. These valves only work if exercised
regularly. The two that came with the boiler's system kit did seem to
last significantly longer, so it could be a quality issue.

I've had more problems from ball valves leaking at te gland than from
any other type.

Eventually they scale up again.


--
If I had all the money I've spent on drink...
...I'd spend it on drink.

Sir Henry (at Rawlinson's End)


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