I have a biasi 24s combi boiler. Dhw working but heating not working, flow pipe from boiler and first radiator hot but the rest only warm, return pipe going into boiler cold, pump very hot and on continuously, ive drained whole system, filled it back up again and bled all radiators, ive stripped down pump and thats ok, but heating still not working.
I have to say , it does sound like pump not working, try disconnecting the pump and see if it is still the same, sometimes what appears to be a functioning pump can be false, as they are driven by manetism they can easily stick if the impeller bearing gets worn.
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