Baxi Solo 3 60PF (6 years old), Cycling

[Wroenco]

I have a Baxi Solo 3 60PF (6 years old). Boiler starts up and heats nicely until water at required temperature, (whether CH or HW), and then powers down, only to refire within seconds.

However, the Corgi man sent of for a new PCB, (on Baxi's advice), and installed it on Monday, only to find the same problem.

Original PCB re-installed, while Corgi man has gone off to query Baxi again. Meanwhile I have Googled all over and found this site.

Just reading up on here I have checked the pump, working fine at all speeds, the 3-way valve, the wall mounted thermostat, the cylinder thermostat and have come to the (non-expert) conclusion that it is the little red flow control thermistor on the flow pipe.

It is securely on. Have photo if necessary.

Please help as it is very expensive taking time off work to accompany Corgiman on voyage of discovery.

TIA

PS: It is my birthday today and I could do with some good fortune!

 

[Vic Spanner]

Check your A.P.S tubes for breaks or splits

 

[Wroenco]

The APS was suspected as earlier when the boiler would not start at all I tapped the APS and it fired up. So given the above advice I replaced the APS. The tubes were OK, if a little hardened at the fan end due to exhaust heat.

I also ended up replacing the thermistor, and finally, after downloading the MI from Baxi and following the fault finding chart, I changed the potentiometer.

It was this last change which restored the boiler to full and satisfactory operation.

Thanks.