boiler overheating??????????????

[harridw]

baxi combi 105e


Can any one Help??
Boiler fires up ok - burner ignites- dosn't appear to be modulate.
The radiators get piping hot no matter what thermostat is set to ........
If you open up tap the water is scalding - eventaully cools to correct temparture.
In a nutshell the boiler will remain on for about 9/10mins and cut off- if i reset the boiler the same happens .
Pressure is fine although slight leak on 1 rad .
Boiler also comes on randomly sometimes without timer clocks say so and tends to kettle befire cut out.....

 

[EliteHeat]

Suspect the PCB

 

[joeho]

My Ferroli sigma 20/40 boiler also overheats when you switch it on. Turning the temperature control knob on the boiler makes no difference.

I suspect it is a simple problem (boiler thermostat or mother board).

How much should this problem cost to repair? I have seen that new thermostats on these boilers are only about 3-5 pounds.

Anyone in the Leeds/Pudsey area want to look at this and fix it for me?

 

[EliteHeat]

The fact that the boiler fires when there is no call for heat would tend to rule out a faulty stat and point more in the direction of the PCB, given the other symptoms.

 

[DP]

Is suspicion reason enough to replace the PCB?

What if, after the PCB has been replaced, the boiler still malfunctions?

 

[scatmanjohn]

Boiler firing without a demand could be the dhw microswitch