Worchester 24CDi CH

[PR]

Ref: Worcester 24CDi Boiler. The boiler appears to work OK, hot water etc. However when the CH is turned on the CH water pressure increases up from 1 bar until water comes out of the pressure relife pipe at about 3.5bar after about 30 min running time. I have noticed that only the top half of the rads are getting hot. I have gone round bleeding all the rads to insure that there is no air in the system. At present I had to turned down the CH temp control to 1.5.

It may not be related, but I replaced the water diverter valve on the boiler due to no hot water (as to the servicing instructions) about a month ago.

Any help is welcome.

 

[MJN]

The expansion vessel could be shot, or require re-pressurising. The non-functioning vessel will be unable to absorb the pressure rise in the system such that the PRV ends up opening.

The failure of the radiators to heat up at the bottom could be build-up of sludge or poor flow rate.

Mathew