Leak In Heating System

[soxmis_sid]

Every other day I have to top up the pressure in my heating system as I must have a small leak somewhere.
Is there a method to finding where the leak is?

[gness]

I guess you mean an underfloor leak....or you'd see it...☺

This happened to me three years ago when I had a new boiler. I was told there was a gadget that could detect a leak but British Gas advised me to repipe.

I decided to have them put something like radweld into the system....against some advice.
I was told it could negate my boiler guarantee but it's been three years now and everything is working very well....so far....☺

[The Builder]

Not without being able to get at the hidden pipework, Sid. A pressure test would confirm that there is a leak, but wouldn't tell you exactly where it is.

Look for a 15mm copper pipe coming out of the wall outside. It's where water is expelled if the boiler's pressure valve is faulty. Put a short length of hose on it. Put the other end of the hose into a bottle or jar. If it fills up, then it's possibly a relief valve fault rather than a leak.

[gness]

Mr Builder....would a damp meter work at all?

[The Builder]

I don't think it would, Gness. If there is a leak, then it's likely to be hidden. Otherwise, it's easily spotted.

[gness]

Thank you, Mr Builder.....I was told to borrow a damp meter to test the floor... but at my age crawling around on the floor needs to have more fun to it than finding a leak...so I went along the stuff in the system route....x

[carrust]

Get some Tenalady gness:-)

[gness]

Rusty....since joining AB I have them delivered in bulk...☺

[carrust]

LOL

[buildersmate]

If we are talking wet UFH here, then I agree with my boss the builder that it is very difficult.

If you have several zones, as most systems do, fed from a manifold, you can pin it down to which zone is faulty by isolating each one in turn, but this needs you to lock down the valve on each zone that controls the volume of water passing per minute through each zone. This is the equivalent of rebalancing a std CH radiator system when you have had to adjust the lockshield valves. In reality, unless you know how to do these things, you are going to have to enjoy a technician.
That tells you nothing more than which zone leaks.
I would approach a specialist before deciding to Radweld the system. It might work but car water systems run at 90 degrees C whilst UFH enters at about 50 degrees and emerges back out at around 25. So the Radweld might not set.

[gness]

Hi, Buildersmate....wasn't actually Radweld the guy used but the same idea only for central heating systems...x

[soxmis_sid]

Thanks for all your help. I'm assuming this is a very small leak as the pressure drops slowly. I have looked around all the joints for leaks and checked under the floor downstairs. There are also no revealing damp patches on any of the ceilings so possibly from the boiler itself?

[alavahalf]

My system did exactly the same and I had to top the pressure up every 2 days.
I checked round all the pipes and valves that were visible and could not find any sign of even the slightest dribble.
I bled every radiator a few times over the next few days. Eventually I made a call to someone I know who seems to have all the answers and he suggested I go outside and check the system drain down valve .... sure enough the valve just needed a slight turn and it has kept it,s pressure ever since.

[soxmis_sid]

Thanks, That sounds like buiders solution too. I'll try that.

[buildersmate]

I've just had to change the expansion vessel on my own UFH system because the membrane was leaking. Having repaired it, I had a minor loss of pressure until I hung a collector vessel on the overflow to find this is where the leak was coming from. Many of the relief valves have a test facility where you can turn the cap on top, which raises the valve seat a little, before it springs back into place, reseating the valve with a sharp snap. This was my problem, and draining down and repressurising the system must have caused a bit of crud to lodge in the valve seat. This caused the leak, even though I hadn't touched the relief valve during the service.
Worth a try.
If it is not the valve, you may find that you can run the system at say half a bar, instead of the normal one bar. Some leaks only show themselves at greater than a specific pressure.