Combi boiler overflow leaking

[robpreece]

This morning I found that my combi boiler pressure had reduced to zero. I re-pressurised the system up to 2 bar and although the system (heating and hot water) is working I'm losing pressure - the overflow is continually dripping at quite a rate. Any ideas?

[The Builder]

Hi Rob...................don't take this as gospel, but I always understood combi pressure should be around 1 bar............................might explain it?

Hang on 'til a proper heating engineer comes along............

[robpreece]

thanks - when it was serviced in September the engineer suggested between 11/2 and 2 bar - problem seems that the escaping water from the overflow is continually reducing the pressure back to zero at which point the system shuts down

[The Builder]

......fair enough Rob...................sorry I can't help.........hope there's someone else out there :o)

[gucciman]

the water is leaking out the pressure relief valve because the valve has opned up to relieve excess pressure and failed to reseat properly.

you need a heating engineer out to examine why the valve opened in the first place and to rectify the problem, i would be looking at an expasion vessel fault.

and yes 1 bar is the correct pressure for most combis, and that is when the boiler is off and cold.

[paulhever]

it sounds like you had the same problem as me, mine was leaking from the condensation trap, i called a money grabber sorry plumber out and it was the heat exchanger that had gone p.s my boiler is a vokera