Hi my boiler looses pressure over night, the pressure gauge shows empty every morning if the heating is switched off over night.I was topping the boiler up every morning which resulted in over pressure.the hot water will not work as there is no pressure in tank, but if i turn on the heating, the boiler will repressurise its self, and after turning off the heating i can run hot water for most the day.The next day the same thing.
I have had a plumber look at the boiler but he is puzzeled as there are no leeks in the system ?

stuart kirke, February 2007

SOUNDS LIKE THE EXPANSIONN VESSEL HAS GONE, MINE RECENTLY WENT AND HAD ONE FITTED EXTERNAL TO THE BOILER FOR £150. YOU SHOULD'NT KEEP REPRESSURISING IF YOU DO NOT ADD A RUST INHIBITOR IN THE SYSTEM AS IT WILL SLUDGE UP YOUR RADS. IF IT IS YOUR EXPANSION VESSEL THAT HAS GONE YOU SHOULD SEE HOT WATER BLOWING OFF ON YOUR BOILER OVERFLOW PIPE OUTSIDE.

CM, March 2007

If pressure rises from1 to 3bar or close when heating is on then expansion vessel has failed and the expansion vessel itself needs repressurising or replacing

mr gas, February 2007

it has done at times!

stuart kirke, February 2007

possibly expansion vessel knackered. When nheating works does pressure rise to above 3 bar?

mr gas, February 2007