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Old March 9th 19, 06:25 PM posted to uk.d-i-y
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Posts: 22,290
Default Looking for a leak


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?


--
Cheers,

John.

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

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Old March 9th 19, 06:44 PM posted to uk.d-i-y
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Posts: 39
Default Looking for a leak

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?
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Old March 9th 19, 07:14 PM posted to uk.d-i-y
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Posts: 857
Default Looking for a leak

On Sat, 9 Mar 2019 18:25:08 +0000, John Rumm
wrote:

Any bright ideas?


Fluorescein dye and a UV flashlight?


Thomas Prufer
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Old March 9th 19, 07:17 PM posted to uk.d-i-y
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Posts: 22,290
Default Looking for a leak

On 09/03/2019 18:44, Paul Welsh wrote:
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.


Handy tip, ta.

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


I can't directly - I can only estimate by how long I turn the filling
loop on to restore the pressure, and compare that time with filling a
container at the kitchen tap. We have high water pressure (~6 bar), so
it can shift a fair amount in a few seconds.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/
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Old March 9th 19, 07:56 PM posted to uk.d-i-y
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First recorded activity by DIYBanter: Jan 2015
Posts: 10,122
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?


Work out where's the hardest bit to get to. It's there.


NT


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Old March 9th 19, 07:57 PM posted to uk.d-i-y
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First recorded activity by DIYBanter: May 2010
Posts: 3,883
Default Looking for a leak

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.
--
Cheers,
Roger
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Old March 9th 19, 08:04 PM posted to uk.d-i-y
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First recorded activity by DIYBanter: Jan 2015
Posts: 10,122
Default Looking for a leak

On Saturday, 9 March 2019 19:56:59 UTC, 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.


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.


NT
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Old March 9th 19, 09:49 PM posted to uk.d-i-y
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First recorded activity by DIYBanter: Mar 2013
Posts: 38
Default Looking for a leak

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.

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?


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