Slow central heating leak

[gaj2002]

Hi, I have a pressurised sealed system with an Ideal system boiler. Unfortunately I have a slowish leak, losing about 0.2 bar pressure per week. It's a big system though, probably 350 to 400 litres.

It's annoying because air gets in and causes airlocks, it takes ages to remove air by bleeding, remove the airlocks by turning other radiators off, turning them back on etc.

There is no visible staining anywhere so presumably it is on the ground floor. I've checked it's not the boiler - I isolated the boiler for a week, its pressure was unchanged, then dropped the 0.2 bar when I opened the valves to the system.

My question is - it's an extended house, the original being suspended floor and the extended parts being screed floor. Is it safe to assume the leak would be under the original house? Would a leak in screed be apparent through staining or damage to the floor?

The leak detection companies are all telling me the leak is too slow for them to find, they want a much bigger pressure drop. But I'm wondering if it is best to try to check carefully the area under the original house.

Thanks

 

[dilalio]

Can you add lever isolation valves at various points so you can narrow down the section that's leaking. This is the easiest way to proceed.

 

[drives]

Try a bottle of leak sealer. It worked for us with a similar slow leak, and no ill effects.

 

[dilalio]

Try a bottle of leak sealer. It worked for us with a similar slow leak, and no ill effects.

I'm a heating engineer and my own system has a slow leak.
I have a bottle of CT1 leak sealer in my boiler cupboard.
Have been loathe to use it for 3 years now!

 

[HERTS P&D]

I'm a heating engineer and my own system has a slow leak.
I have a bottle of CT1 leak sealer in my boiler cupboard.
Have been loathe to use it for 3 years now!

Can you add lever isolation valves at various points so you can narrow down the section that's leaking.



Andy

 

[dilalio]

Can you add lever isolation valves at various points so you can narrow down the section that's leaking.



Andy

Nope! Pipework is all hidden and besides... I know the leak is under suspended ground floor, covered throughout with wooden flooring.

And I ain't pulling that up for a pressure fault that only occurs every 3 months!

But I do see your joke mate

 

[jj4091]

Nope! Pipework is all hidden and besides... I know the leak is under suspended ground floor, covered throughout with wooden flooring.

Don't you have an easily accessible access hatch. Under the stairs for instance

 

[Roddy Young]

I am puzzled to read that air gets into your system. If it's pressurised, air cannot get in.
(That's like imagining a car tyre filling with water when you go through a puddle.....)
Are you sure it has anti-corrosion additive? Maybe the "air" you have to bleed out is hydrogen.

 

[dilalio]

I am puzzled to read that air gets into your system. If it's pressurised, air cannot get in.
(That's like imagining a car tyre filling with water when you go through a puddle.....)
Are you sure it has anti-corrosion additive? Maybe the "air" you have to bleed out is hydrogen.

AAVs

 

[dilalio]

Don't you have an easily accessible access hatch. Under the stairs for instance

No and not enough crawl space.

 

[Razor900]

No and not enough crawl space.

Just fit a 50L expansion vessel and top it up once a year instead

 

[Roddy Young]

AAVs

How does an AAV allow air into a pressurised system?