Combi Boiler Pressure

[mthorniley]

I've recently moved into a new house with a worcester Bosch Greenstar R35 HE Boiler.

On the moving day, the lad who owned the house found an isolating valve weeping and changed it while the system was still pressurised.

I have a strange problem where the boiler shows zero pressure when cold, but kicks in and raises to 1-1.5 bar when running. It does not go into lockout and seems to run ok.

I've bled all the radiators and water comes out

Just wondering if the expansion vessel needs recharging. The Relief pipe feels wet inside but that may be where I have topped up when cold and then Its gone above 3 bar when running.

There are no visible leaks. The house has solid floors so everything is under the upstairs boards so leaks would be visible.

 

[BigSnoopy01]

was it serviced/ checked before you got the property? do you have Indemnity insurance with the purchase?

you need to be a gas safe engineer to remove the case on this boiler, best get a local engineer to take a look. Water should only leave the overflow pipe at 3 bar and above assuming the gauge is working correctly.Best not to run the boiler at zero pressure.