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Central Heating

Boiler losing pressure when not in use

Our 8yr old combi boiler works fine day-to-day when we’re regularly using hot water, but when we are away from the house for more than 24hrs the pressure drops to below 1 bar and we have to re-pressurise it for it to work.
We’ve only been in the house a few months so not had the central heating on yet.
Could the problem be with the boiler itself? Or is it more likely to be a leak in the system? Is there a straightforward way to find out which it is?

5 Answers from MyBuilder Heating Engineers

Probably the Expansion valve or pressure release valve. Plumber will sort no problems

2019-09-24T08:55:02+01:00

Answered 24th Sep 2019

Most likely to be 1 of 2 things . Either a slight leak in the heating system or the pressure vessel inside the combi boiler needs re-pressurising or replacing.

2019-09-24T08:55:02+01:00

Answered 24th Sep 2019

It could be either the boiler or the system, in these cases you'll need to get the boiler and system looked at by a heating engineer to diagnose where the fault lies and the loss of pressure which isn't healthy for either boiler or system

2019-09-24T08:55:02+01:00

Answered 24th Sep 2019

A failed pressure relief valve or a depleted expansion vessel.

2019-09-24T08:55:02+01:00

Answered 24th Sep 2019

It's most likely a small leak going undetected, could be under the floor. Water is escaping from the system somewhere. The other possibility is your pressure relief valve is passing water, this would leak from the small copper pipe outside where your boiler is

2019-09-24T08:55:02+01:00

Answered 24th Sep 2019

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