Dear Site,

We have a Baxi Combi 105e, which appears to have a weak PRV, in so much that it is losing pressure from 1.5bar to>0.5 bar over the period of a day. When filling the loop, it is impossible to refil past 2bar, as water passes out from the overfil pipe outside, via the pressure relief valve. Assuming the PRV is faulty, how is the PRV replaced -is it necessary to fully drain the system first? Many thanks in advance. Rob.

Rob, January 2010

you can turn of the flow and return pipes on the boiler, the two on the out side edges of the boiler under neath, turn the rad cap on te PRV till the water stops running then you can take the valve out, some unscrew some are held in with a grum screw. Once you have fitted the new one ceck the persurin te red expansion vessel on the back ou the boiler wit a tyr gage should be about 1.5 bar if not refill with a bike pump. turn on te valves and refil as normal

erj, January 2010