Another Baxi Solo Overheat Problem!

[zrx]

Searched through the forum but couldn't find anything similar to this.

We have a Baxi Solo 2 PF which developed an overheat fault yesterday. Haven't made any changes to the system recently, problem happens with both hot water and central heating.

Boiler runs for about 10-20 mins with boiler, fan, pilot & burner lights all on. Then boiler light goes out but the fan, pilot & burner lights are still on with the flame burning. The boiler and pipes make lots of noise until the overheat light comes on and the burner shuts off with the pump running continuously.

At first suspected the pump and turned this up from II to III but this has made no difference. Have ordered a new one anyway but am also wondering if this could be a PCB problem - if the pump over-run is not working then this could also explain what's going on. Have tried to check whether the pump is running once the boiler light goes out but this was difficult after running upstairs and trying to hear whether the pump is running while the pipes are popping and whooshing! Pump is running when the overheat light is lit however.

Can you help?

 

[zrx]

Have now found that once lit the boiler won't turn off until it goes into overheat or you turn the whole system off at the mains - neither of these seem like a good idea!

Turning the boiler off using its' own control or turning off the hot water demand from the controller have no effect - the boiler keeps burning. I'm now pretty sure a new pump won't fix this. New one has arrived but one or both stop valves either side of old pump still let through water even when turned off. Looks like I'm going to have to drain thge whole system

Can anyone help me please? Is a new PCB required or does this sound like something else at fault?

 

[gazthepottertonengineer]

Check to see if there is power to the switched live if there isn't and boiler is still running must be pcb! If there is power to switch live when no Hot water or heating demand then you have a controls problem!

 

[zrx]

Thanks gaz. it was indeed the PCB - that now makes four that have been fitted to this boiler. This has got to be shoddy design work!!!