Ideal C80FF combi problem

[relief123]

I came home tonight and the heating was on full blast, the heating thermostat wasnt on, I turned the whole boiler off and wheneva you turn it on it fire up even though no hot taps are running or the thermos on.
The heating was on even when the heating switch was just turned to hot water only.
The only thing that turns it off is the water temperature knob for the hot water.

What can this be and how much will it cost to get put right and could I do it myself, I do a bit of plumbing..

Thanks

 

[lor]

flow switch stuck on

 

[relief123]

Thanks mate...

Dont spose there is any way of unsticking it for now or is it a replacement job.

 

[relief123]

Is there any other thing that it could be rather than the flow switch.

 

[HarrogateGas]

Possibly the PCB or yor external controls but this is rare.

 

[relief123]

I have just drained down system and repressurised, now it works however the heating doesnt work, but at least the problem with the boiler being on constant isnt an issue, and the hot water is ok with the boiler turning off on when water goes off on

 

[Agile]

The flow switch will be on due to a stuck diverter or due to the gland having leaked water into the DHW flow switch, more often the latter.

This is not a DIY job because the gas valve has to be removed to access the switch. I did once hear of someone who managed it by removing the whole of the diverter valve assembly instead but that is quite a job and would even take me more that an hour.

Tony