So I have a Potterton Promax HE boiler, I have not used the CH all summer; the boiler has worked fine all summer for the DHW. Now it’s getting colder I went to put the CH on and for some reason it doesn’t work. When the selector switch is on CH & DHW the LED does not come on for CH but it does for DHW and the DHW works ok. As the CH worked fine last year, I started off by checking the basics I could think of, so I increased the water pressure to 1.5 barg, turned the wall thermostat up to max can hear the relay clicking in. There are no error codes coming up. Checked the settings on the programmer both CH & DHW set to 24 hours and run. Checked the fuses and the 2 local fuses to the PCB were 3.15 amp, according to the User Guide they should be 2 amp, so I changed them both out for fast blow 2 amp fuses. This did make me think that maybe the PCB had been damaged due to the wrong fuses been fitted, so I put my PCB in exchange for a reconditioned one and the fault was still the same. I spoke to the manufacturer of the boiler and they said it sounds as though the programmer is not, telling the CH to come on even though everything appears ok on the screen. So I changed the programmer and the fault is still the same. I assumed if there was a fault with one of the sensors it would come up as an error code, but I was running out of ideas so I checked the sensors to the best of my ability and they appear to be ok. The pump is free and runs, but it does appear to be running continuously? One of the main things I haven’t fully checked is the three way valve, but I thought the CH would still run just not circulate warm water to the radiators?
So that is basically were I’m at does anybody have any ideas what the problem is please.
So that is basically were I’m at does anybody have any ideas what the problem is please.