Pressure down then up.

[dav657]

Seeking advice from the experts. I have a Baxi 150HE combi boiler. Been losing some pressure since we started reading using the central heating a few weeks ago after around 3 month's of not using apart from hot tap and shower water. No obvious leaks or beneath floor on areas that I've checked. No discharge from prv. Loses Pressure whilst heating is on. Weird thing is that when it's switched off and cools down it loses half a bar pressure from what the pressure was when switched on and run for a few hours. We then go to bed and by morning after around during 8 hours, whilst switch he'd off it regains the half a bar pressure. After a few days it has lost around a third of a bar and I top up. Also the boiler switches itself off even though a couple of radiators no longer get as hot as they used to. No air in rads.

 

[Billy Bob Bob]

Baxi 105,s are considered to be one of the best combis to hit the uk market,normally very reliable and well behaved,you need a GSR Engineer to sort this for you,you can either post in our find a plumber/gas engineer section or go direct to Baxi for a one off fixed repair,whatever you decide to do,do not replace it unless its a instant version ,seen one ripped out recently that only needed a pump Repairs [DLMURL]http://www.ukplumbersforums.co.uk/im-looking-plumber-gas-engineer/[/DLMURL]

 

[dav657]

Thank you very much for your reply. Our Baxi 105 boiler is the HE version with instant hot water. We have breakdown cover and the Baxi engineer checked it out, but couldn't find anything gets wrong. He didn't have an answer for it regaining pressure when cold overnight. I have an engineering g background d and although I may be completely wrong - to regain lost pressure, water has to somehow come back into the boiler where the gauge is. It seems to me that the only place that can come from is the pressure vessel maybe initially retaining water then gradually releasing it? The vessel was checked and pressure ok.