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Plumbing

Constant water loss through PRV after powerflush

Anonymous user 15/03/2024 - 2.52 PM

Hi I had a powerflush completed. No issues or leaks during flush. However the system is constantly leaking water out the PRV valve and I’m having to top it up every hour. Have checked and repressurised the cold feed expansion vessel and heating expansion vessel. That slowed the water loss down to begin with. When checking the heating expansion vessel got a tiny amount of water vapour out. Could hear a constant hiss sound like air is being lost from the PRV. Do you think it’s the heating expansion vessel that is the issue and replacing it will fix the issue? Update - Replaced the PRV, checked the expansion vessel then topped up system to 1 bar. System rises to 1.5bar when on. No pressure loss at all. Thanks for the help.

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3 Answers

Gas plumbing and heating

Rating: 4.9 out of 5

Tottenham, London

You must change the expansion vesel and prv both off them they are gone

Answered24 November 2019

D & R Property and Plumbing Maintenance

Rating: 4.9 out of 5

New Romney

you should not get water out of valve,this means membrane has gone,it needs replacing ,prv may be ok once expansion vessel is changed,if you do not want to strip boiler to get to expansion vessel ,you could fit an expansion vessel external on heating pipework.

Answered27 November 2019

Anonymous user

I don’t fully agree, yes the pressure relief valve could be passing, but that could just be debris, there could also be a very slight leak on a radiator valve, sometime tiny leaks on pressurised systems can be missed , and are hard to detect, unless you are looking for them, inspect all rad valves first and , as for the PRV, try turning the spring cap for a couple of seconds to activate it, that should clear debris

Answered4 December 2019