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Central Heating

Boiler losing pressure, no leaks, not the expansion valve

Anonymous user 03/03/2024 - 3.26 PM

Hi all, I’m really hoping someone can give me some guidance because I’m at the end of my tether. We have an Ariston 25HE boiler which in September started losing pressure about once a day. This got worse and it got to the stage where it was losing pressure every four hours. If it had been up to me I would’ve had someone in straight away but we lived in private rented accommodation and the landlord was dragging his feet. Finally I got someone in and said I’d be taking the cost out of our rent, and the tradesman replaced the expansion valve. This was on October 25 and until now (November 10) everything has been working fine but this morning the boiler lost pressure again. On both occasions there are no signs of leaks (we’re a mid floor flat so with the amount of water I imagine we would have heard from downstairs if there was a leak and there’s nothing on the ceilings), and the copper pipe which turns back into the building was leaking previously - which is what led us to believe it was the expansion valve, I haven’t seen it leak this time yet but will keep checking (it’s too high up to tie a bag to as some have suggested). So can anyone give any suggestions on what we can do next? The problem we have is getting our landlord to do anything is a massive struggle so I want to be able to go to him with a suggestion of why the problem could be. Thank you in advance!

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4 Answers

D & R Property and Plumbing Maintenance

Rating: 4.9 out of 5
New Romney
it may well be the expansion vessel that needs topping up or if defective replacing ,when a prv on a boiler has lifted you should first check the charge in expansion vessel,this would be the first thing to check before changing the prv,failure of expansion vessel leads to overpressure of boiler making prv open.
Answered10 November 2019
5

BPH

Rating: 4.6 out of 5
Trowbridge
Aswell as the expansion vessel, get an engineer to check there isn't a crack in the heat exchanger and passing through the condense pipe. The only way to tell this would be to isolate the boiler on both sides of the heating and leave overnight. If pressure drops you need a new heat exchanger
Answered28 November 2019
2

JRZ HANDYMAN

No reviews yet

West Norwood, London
You might need to top up the expansion vessel with compressed air
Answered11 November 2019
0

Lacey Heating

Rating: 5 out of 5
Hertford
It could potentially be the heat exchanger leaking internally and running in to the condensate
Answered27 November 2019
0