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Central Heating

Boiler pressure

Hello, I’ve had a problem with loosing pressure on my boiler for a while now. I’m topping up every other day when I use the heating. So I’ve had a new boiler fitted and the problem is still there. I’ve got no leaks on my radiotors and I’ve checked all the pipe work under the house and there’s is no leaks, I’m stuck now on what to do. Any help would be brilliant cheers

10 Answers from MyBuilder Heating Engineers

Best Answer

Have the expansion vessel checked as may need recharging
Or pressure relief could be faulty
Check if PRV pipe outside is dripping or any signs of water

2020-01-13T09:55:02+00:00

Answered 13th Jan 2020

It’s very simple, if you put water into a piped system and seal it the water can’t get out. If the water gets out you have a leak.
First point of call is usually the radiators, valves and pipework. All visible pipes. If they are dry the second place to look is the boiler and it’s pressure relief valve. The PRV can be checked at it’s outlet which is usually outside directly behind the boiler (15mm pipe with a bend towards the ground). With a new boiler one would hope this would not be leaking. If the boiler and the visible pipes are dry your leak will be in the pipes under the floor or in the ceiling. If it’s the latter you will have visible staining. If it’s the last resort you will have to take up the floor or replace all the underfloor system.
Silly question but why did you allow a gas engineer to fit a new boiler in an unsound system?
Guy

2020-01-13T09:55:02+00:00

Answered 13th Jan 2020

If you're topping up every other day with a brand new boiler I'd suggest you almost certainly have a water leak on your system.

If you have a particularly large radiator circuit there is the possibility that your expansion vessel is undersized for your property size which would cause pressure related issues but, beyond that I think you're looking at a leak like I say.

2020-01-13T09:55:02+00:00

Answered 13th Jan 2020

Is it a combi boiler? Could be a problem with the pressure relief valve or expansion vessel. It could simply be you have air in the system some where. Have you tried bleeding your rads? Start down stairs and work your way upstairs, if you have towel rad in the bathroom then bleed that last. If you are in doubt, call a gas safe engineer. Hope this helps

2020-01-13T09:55:02+00:00

Answered 13th Jan 2020

"I’m topping up every other day when I use the heating."
This is possibly your clue to your problem.
How much are you topping up ? to what bar?
So do you loose pressure when the heating off?
What temperature are you running your rads / boiler? Are you at the Max?
Have got water evaporating / dripping from a small white pipe? (this may be outside or hidden someplace.
If all the above is normal then you still have a leak in a pipe some place and likely on the ground floor. Unless you see wet patches on the ceiling......:)

2020-01-13T09:55:02+00:00

Answered 13th Jan 2020

It sounds to me like there is definitely a leak in the system somewhere if you are still loosing pressure as you say you have had boiler changed and still loosing pressure maybe pipe in wall underfloor usually joints leak causing problem
Otherwise would be leak within boiler
Don’t no how old your new boiler is but if you have had new boiler installed and still same problem sounds like leak in system somewhere

2020-01-13T09:55:02+00:00

Answered 13th Jan 2020

if new boiler is ok then you must have a leak.

2020-01-13T09:55:02+00:00

Answered 13th Jan 2020

Before we can answer the question what kind of Central heating system does this person have?

It is unlikely but the boiler that is been installed may have a fault with it.
Has the customer checked the expansion vessel and the pressure relief valve?

If the central heating is losing pressure you will have a leak somewhere, It may be very small and may be difficult to detect unless you have a train eye.

2020-01-13T09:55:03+00:00

Answered 13th Jan 2020

Your boiler system is a sealed system . As the name suggests its sealed like a tyre on a wheel . Assuming the expansion vessel is ok . ( does your boiler have one or is it external ) . And the pressure release valve on the boiler is not open . ( it usually exits through the wall to outside ) you have a Leak somewhere . The pressure is the water pressure in the boiler and it cant drop unless water is getting out somewhere . The trick is finding it . And having had a new boiler fitted it is not likely to be the boiler thats at fault . I hope this helps .

2020-01-13T12:35:02+00:00

Answered 13th Jan 2020

The pressure on the boiler gauge is for the boiler, radiators and central heating pipework. Especially with a new boiler one liter of water can be shown on the gauge with a fall from 1.3 bar to 0 bar.
So there is definitely a leak underneath the house but is getting soaked by the ground and is not easy to find it.
Try a dose of leak sealer and repeat the treatment after two weeks if still loosing pressure. Cheers

2020-01-15T08:05:02+00:00

Answered 15th Jan 2020

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