Combi Boiler Tripping out on high pressure

Hi,

Having problems with my heatline S30 COMPCT combi boiler. Struggling to get an engineer that touches these boiler.

The symptoms of the problem are When the CH comes on the pressure rises from 1.5 bar to above 2 bar then cuts off. Then the system needds to be reset.

Similarl, when the DHW is asked for the pressure quickly rises to beyond 3 bar and the relief valve activates. The system then needds to be reset.

None of the indicator lights flash indicating a fault. I believe when the DHW is called into duty the pressure should not change as this is part of the CH system. The only common part is the diverter valve. The solenoid which operates it appears to be functioning and the plunger on the divertoer valve appears to work manually.

However, I still do not have heating or hot water.

Any help would greatly appreciated

have you checked the charge pressure on the expansion vessel? Should be set at around one bar? a handy type pressure gauge should come in handy, if it;s below try pumping it up and see wot happens

Hi Plummerman,

I had a plummer look at it and he checked this and everything was as it should be. He did not have much luck with trouble shooting the internal workings any further though.

The strange thing is that the pressure guage on the system should only, under normal running, provide the pressure in CH side of the system. The concerning issue is that when only the DHW is switched on the pressure guage rises dramatically within 30 seconds after the burner lights and activates the pressure relief valve.

I thought it might be the 3 way diverter valve (or some operation related to the diverter valve) which is common to both the CH and DHW systems.