Leak at boiler help!!

[peter wilson]

Hello
I have woecester greenstar he 30 plus combi boiler. Pressure gauge dropping half a bar over night. I isolated the boiler from the heating system, no lose of pressure. Nothing been lost fron auto air vent or pressure relief valve, no visable leaks.
It only looses pressure when boiler is running, my thoughts are poss crack in primary exchanger , water getting in to combustion chamber. Any one no of any where else the water could be going.

Peter

 

[stevetheplumber]

doess it lose when connectted to system but not running ?

 

[peter wilson]

hi steve
when connectted to system and not running it keeps its pressure