pic from under the boiler far right pipe is expasion pipe, then heating return, then cold feed, then gas, hot water and heating out

mmm, so if its behind the heat exchanger on the preasure release valve side, as thats where the expasion pipe comes from, unless its behind the big metal burner part at the top as i wouldnt of thought a 12ltr one would fit anywhere else?

Its hard to say with out having a poke around it, its a 12 ltr one in them so it wont be small

how would i get to that? as that bits on the wall.

no, thats an automatic air vent

from the pics it looks like it could be at the back behind the heat exchanger, behind the silver plate

is it that thing on top of the pump?

i cant find anything that looks orange or red in the boiler? ive got some pics if that helps

i take it , it will be behind the big heat plate?

yeah you cant miss it really, their normally red or orange, will most probably be on the side if its a baxi, the valve will be easy to get to, pump it up as you would a car / bike tyre

its a baxi combi eco80 is there just a valve to attach the pump to? the picks i found look like an orange hockey puck

in fact when you see the vessel push the valve down to see if any air comes out, if water comes out its goosed

put in google images expansion vessel

Make sure the pressure guage on the front of teh boiler is on zero

well ill have to unscrew the front first to have a look, what does it look like

bike pump or summat, it has to have a pressure guage on it though, does it say on the boiler what the pressur eshould be? its usually 1 bar or there about

ive not got a foot pump are they best to use or will anything with a preasure gauge do, going to look tomorrow

thankyou people will give it ago

haha gas engineer lol

I take it your a plumber as well then

u have to dump the pressure 1st then pump up to one bar.. if u can get to the exp vessel take the dust cap off and push the pin if water comes out brust if air flat

its the expansion vessel in the boiler is either failed or simply needs re charging, they just pump up like car tyres

but would the preasure not increase even when off then

pissibly a let by on the filling loop so is slowly filling and passing the relief valve pressue when hot.

If your combi boiler keeps building up preasure when the heating is on, then not dropping back down when cold what could be causing this?, it keeps going up to 3 bar and then dumping water out the relief valve, any ideas have searched and could it be that the expansion vessel needs recharging?