Baxi Solo Overheating

[simms5280]

I have a Baxi Solo Bolier.

When i call for hot water the boiler fires up for around 3 minutes (noises from the boiler get louder during this 3 minutes)then the overheat switch goes and i have to leave it a good 5 minutes before it will reset.

When i call for central heating the boiler does not fire up at all. So i dont know whats wrong with that.

I have had all the electrics checked and they are fine, the pump is also new aswell. Could it be the diverter? Valves ?

Im really lost now

 

[gas4you]

Sounds like lack of circulation. I would firstly check there is 230V at the pump when the hot water is on. The boiler pcb supply's this so if there isn't it could be a pcb failure.

The not coming on on heating sounds like a zone valve fault. If you have 2 zone valves then check for 230V at the orange wire from the heating valve. If a 3 port valve then do the same.

 

[coggy101]

Even if you have 230V on the zone valve, check the small wheel at the side. It should rotate to a flat side when driven open. Sometimes they will fail to open even with the 230V applied. This water blockage will stall the water flow through the boiler and cause an overheat trip.