Potterton Kingfisher Thermostate problems

[awmw]

Hello

I have a Potterton Kingfisher MF RSL60 boiler.

The problems seam to be with the thermostate as the boiler will keep running and not cut out when the water is too hot, resulting in the radiators becoming very hot (100*c).

Every now and again, the boiler will shut off and a relay type clicking sound can be heard which I think is the thermostate switching on and off about once a second and the fan speeds up and slows down.

This will continue for about 30 seconds and will end with the boiler firing up or staying off but if, during the clicking, the temperature control knob is moved up or down then the boiler will fire up.

I crudly tested the temperature control varible resistor with a multimeter and i appears ok with no dead spots.

I replaced the thermistor with a new one as they are cheap and I thought it was worth a try but it made no difference.


Any ideas?

Thanks
Adrian

 

[ChrisR]

Hope you used sufficient thermal paste on the sensor.

But it sounds like a pcb problem - or connections to/on it. Hopefully a potty guy will know...

 

[awmw]

Yes, I used plenty of thermal paste.

I'm hoping it's not the PCB as that sounds expensive

 

[cozzmic]

Check for water in your system. Had same symptons on the same boiler thought it was the stat but turned out to be low water in the boiler followed by a fault on the PCB (the clicking).

 

[awmw]

Cozzmic,

This sounds interesting.
Are you saying that low water caused a fault with the PCB or that you just happened to have both faults at the same time?

What's the best way to check the water level?

Both hot water tank and radiators get very hot.

 

[baxpoti]

If you have replaced the thermistor and checked the potentiometer
it only leaves, other than the wiring loom, the control board to change.

The clicking noise/ fan oscillating also points at a control board related problem