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Central Heating

Decreasing boiler pressure. once topped pressure keep increasing over 3bar


I recently changed a rad in my hallway. Ever since then I've had problems with my boiler pressure. I left the pipes exposed for a few days to make sure there wasn't any leaks before replacing the flooring.

At the moment overnight the pressure keeps decreasing to around 0.5 andwontkick in. I top it up to 1-1.5 and with with 10 minutes the pressure surges up to 3+ bar. Do you think I have a leak or is it the boiler?

2 Answers from MyBuilder Heating Engineers

I don't think changing your radiator was the main problem. I always ask customer to be cold for a while and do a standing test. Pressurise the boiler to say 1 bar and leave it for 24 hours. If it goes down you have a leak. Leaks may not always be obvious - a joint can let pressure out without leaking. If the pressure goes up and down like a yo yo, then the expansion vessel may be faulty. If the pressure goes constantly too high, you may have a blockage in the system or heat exchanger, or in rare cases the system is too large for the expansion vessel. I hope this helps.


Answered 12th Feb 2015

You need gas engineer to recharge your expansion vessel. Or just keep one radiator full of air :-)


Answered 14th Feb 2015

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