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Plumbing

Weter Pressure dropping after heating is switched off

Anonymous user 28 February 2024 - 4.08 PM

My water pressure keeps on dropping after the heating is switched off. I have to fill up the boiler two or three times a day it is not leaking from the overflow the expansion vessel looks fine, there is only air in one Rad when the pressure drops that is closest to the boiler upstairs, and is fine when re-pressurised, all other reads are ok. I cannot see any damp or mould in the property. The boiler has been isolated for about 10 hours and it has not dropped in pressure so I still have hot water. When the valves from boiler is open pressure drops instantly again. I believe there might be a leak somewhere I don’t know what else it could be or what to do

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3 Answers

DRAIN-CLEAR(NW)
DRAIN-CLEAR(NW)
Rating: 5 out of 555362 reviews
Deeside
There are a few reasons why your boiler may be losing pressure when it is switched off. It may be that there is a leak in your pressure relief valve or that there is air in your system. There may also be a small leak that you have yet to notice on a radiator, or the network of pipes.
Answered2 December 2023
9
Jamie Whibley

No reviews yet

Putney, London
If you have isolated the flow and return on the boiler via the isolation valves and the boiler maintains pressure then the pressure loss will be from the system. Any pipe work under concrete floor should be inspected. That being said, it is still advisable to get a gas safe engineer to check the boiler.
Answered2 December 2023
2
T S Plumbing and Heating
T S Plumbing and Heating
Rating: 5 out of 55511 reviews
Kendal
Will be because your expansion vessel has either deflated or failed completely. Pressure will rise when heating is on and boiler will keep that under 3 bars when it is on, as everything cools down the water pressure drops as the water takes up less space when colder. Even though there is the same amount of water in the system as when warm, the cooler water takes up less space so pressure is lower.
Answered9 December 2023
0