Worcester bosch highflow 400 pressure rising and falling??

[eddiemacthedog]

Right folks,
I woke up this morning and the place was freezing, so looked at the boiler, pressure had dropped to 0.6 bar, topped it up to the bloodline setting on the boiler 1.2bar, switched on and off a few times nothing, found a reset switch under the control panel which must be a overtemp switch i presume, pressed that and away we went.

The pressure kept rising and rising and seemed to settle at 1.7 bar. I was out in the garage for a couple of hours and when i came back in the pressure had fallen back to 1bar or thereabouts, topped it up again and it had tripped with the overtemp again.

i put the heating on full to check it all out again and the pressure started to rise again, currently at 2.2bar, the blowoff is set at 3 bar but will switch it off if it gets near that.

The pump seems to be running red hot dont know if this is normal and all radiators seem to be heating ok, its just the pressure.

im no heating engineer so would appreciate some guidance, also the expansion type vessel at the front of the boiler should this have water in it??

cheers

 

[45yearsagasman]

It does indicate your expansion vessel is at fault. Depressurise the system and check the charge pressure is at approx 1 bar. If not, pump it up. If at some stage, water comes out of the Schrader valve, then a new EV Is required. Easy job on that boiler.

 

[eddiemacthedog]

Ive got boilercare thru sse and the guys due tomorrow, is that an easy thing to check as im no heating engineer but reasonable diyer.

 

[45yearsagasman]

Very simple for a heating engineer to check. He should be able to confirm if the EV is ok or not in 10 minutes.