Baxi 105he fault! Having a trouble getting to the bottom of this one. When there is a heating demand the DHW tap symbol flashes on/off at the same time as the pump running for 1sec on 1sec off. There is no ignition and no red fault lights flashing. Nothing happens when hot tap is running. Changed pcb but still the same. Any ideas??
Baxi 105he pump pulsing on/off
- Thread starter Buzzbar
- Start date
- Joined
- 5 Nov 2024
- Messages
- 4,505
- Reaction score
- 2,203
- Country
- Joined
- 5 Nov 2024
- Messages
- 4,505
- Reaction score
- 2,203
- Country
Ok. Anything you’ve tried but not stated in your opening post?
- Joined
- 5 Nov 2024
- Messages
- 4,505
- Reaction score
- 2,203
- Country
Thermistors checked for correct operation and tolerance? Disconnected external controls? Polarity checked?
Thermistors checked and all fine, only a Drayton hardwired roomstat which is operating correctly. With hot tap running nothing happens atall , power light remains on but nothing else, diaphragm activates pin and activates micro switch and nothing happens, no DHW demand light and no ignition.
very strange fault
Was it a brand new pcb or reconditioned and definitely not an instant pcb by mistake . Earth wires from and to pcb re connected /altered
Correct wires put back on sensors / red to ch sensor green to hw sensor
Has anything else been done to boiler ?
Polarity well worth a check
Was it a brand new pcb or reconditioned and definitely not an instant pcb by mistake . Earth wires from and to pcb re connected /altered
Correct wires put back on sensors / red to ch sensor green to hw sensor
Has anything else been done to boiler ?
Polarity well worth a check
Brand new pcb and the fault is exactly the same as old pcb and it’s not an instant board defo correct pcb. Nothing else done to the boiler it was all working fine with heating and hot water up until yesterday when it tripped the power and when power was resumed it is doing as described in my first post.
certainly a head scratcher
