Ideal boiler only ignites when thermostsat is set to zero?

[twalker]

Ideal minimiser SE 80

Yesterday, the radiators went cold and I discovered that the boiler was not igniting.

I tried various things, including resetting the overheat, dry fire and flue thermostats. By accident, I discovered that the boiler would ignite if the control thermostat was set to 0 (normally have it on 4).

Now, both heating and hot water are working OK (radiator temperature feels higher than normal, hot water is limited by a pipe thermostat and feels roughly normal). If I move the control thermostat above zero, either the boiler cuts out immediately or does not re-ignite during the next cycle. Put it back to zero and it seems to work quite happily.

Is the next step to get the control thermostat replaced? Or is something more sinister afoot?

Thanks for any help.

 

[ChrisR]

If the stat is separate yes change it - won't be too expensive. If the knob operates a potentiometer on the pcb though, that may have a cracked track, which really means a new pcb.