i have a 6yr old combi
which if the heating and water are on will cut out or go to reset
fill boiler to 1.5 bar when stone cold as it warms up spits it out side then cools down to red under half a bar and starts messing around wooring but wont light till cold and the water is off
water stone cold this morning turned ch on water off
half hour later water was hot
pressure valve has been changed and dial british gas
say there must be a leak but no sign any where to warrant rapid pressure drop
when boiler starts needle jumps from 0.1bar to about 1.5bar
please help driving me mad
and british gas seem unable to trace

rob, January 2010

with NO water pressure in the system, test the AIR pressure in the expansion vessel,the large disc thing with a car valve on it. depress the core valve center quickly only AIR should come out,no air pressure vessel has lost it charge no problem re inflate using a car pump to about 1 bar.max. now refill the water system to 1to 1.5 bar cold
NOTE
if water appears from car valve ,the internal vessel diaphragm has failed replacement expansion vessel needed

wirecutterman, January 2010