Slow leak from central heating

SimonSeys

Hi all,

I have a slow leak from my central heating. I can tell this because the pressure on the combined boiler falls slowly. Originally I thought it was the combi boiler, and the gas engineer came out, replaced the overflow valve and then tested the system by running it at 70 degrees (May have been higher) and then tested the pressure held steady.

Now over the course of a week or so the pressure slowly falls from around 1bar to zero if I let it.

I’ve seen leak fixing stuff you can put in the system. I’m competent enough to put inhibitor in the system. Is putting leak fixer in the same diy category? And if so any recommendations?

Thanks,

Si

sheslookinhot

My first focus would be finding the leak and resolving the cause.

luckbox

We had this. Turned out a plastic pipe in the loft had been chewed by a thirsty squirrel causing a leak. Got it replaced with a copper pipe and blocked the gaps into the loft. No more issue. You need to find the leak

elsien

https://forums.moneysavingexpert.com/discussion/comment/81913067#Comment_81913067

Easier said than done though. I had a slow leak like the OP for quite a long time. which suddenly got a lot faster and ended up with water coming through my ceiling because it was a pipe under the floor. I would have only found it by emptying every room in turn and pulling the carpet and the floorboards up till I got to the right bit.

Unless someone has an easier leak detection method, when it is out of sight?

I am presuming the OP has already checked the obvious visible pipes and thermostats.

rob7475

A leak is always hard to find. It may be worth starting with something easier like the expansion vessel. If you top up your pressure and then run the central heating, the pressure gauge will probably rise slightly. Keep an eye on it and see if the pressure rises to around 3 bar before dropping off quickly. If it does, it would suggest that the Expansion vessel has an issue and the PRV is triggering which would explain the pressure drop.

SimonSeys

it’s not the expansion vessel, and it’s not the boiler. Those were tested and the pressure those then held steady when the engineer put it into test mode and ran it very hot for ten minutes. (This was after the PRV was replaced).

if I knew where the leak was I would fix it. I can’t find it.

Does anyone have experience of the sealant systems?

elsien

It was next on the list for me to try, but circumstances overtook me.

It may have delayed things, but it wouldn’t have been have been a long-term solution for me anyway due to the ultimate cause of the leak,

SimonSeys

https://forums.moneysavingexpert.com/discussion/comment/81913123#Comment_81913123

Yes. This is the case with me too.

WIAWSNB

https://forums.moneysavingexpert.com/discussion/6656459/boiler-losing-pressure#latest