my alpha boiler looses pressure through the copper overflow pipe to the outside (puddle on floor) every couple of days,is it something to do with the expansion vessel,or something else .is it repairable by self or too difficult ..thanks.

barrie green, October 2006

Expansion vessel or pressure relief valve. Drop water pressure from system and check that the air pressure in the vessel is 0.8 bar (you can do this with a normal car or bike pump) repressurise water in system back to about 1.2bar and then test over next few days - is the air pressure still the same or has it gone? If it has then it's the vessel that's damaged and you need a new one or an external one. If not then its time to change the prv.

Ben, February 2013

pressure relief valve

hi-spec plumbing, October 2006