Ferroli boiler water temperature

[paul39]

Hi all,
I am probably going to answer my own question here but would just like to see if there are anymore options before i order a new part.
OK, I have a Ferroli F24B combi boiler and the problem over the past couple of weeks is that when hot water or heating is called for the boiler fires up ok and works normally, except that when the desired temperature is reached the boiler doesn't stop. It is finally stopped by the saftey thermistor and then everything runs cold for a couple of minutes until the boiler fires up again and the cycle is repeated.
I have checked the hot water senor and that seems ok as the temperature dispay is pretty much the same reading as i get with a thermometer.
Will i need to change the main PCB as it is not controlling the temp or is there something else that may be wrong.
thanks

 

[diamondgas]

You say this happens the same on heating also yeh? Are you GSR Paul?

 

[paul39]

hi,
Yeah this happens on heating aswell as water and no I'm not GSR I'm a time served industrial maintenance technican, this is my home boiler that i'm having probems with. All i have done at the minute is check the temp on the front display is similar to the temp of the copper water out pipe with a IR temp monitor and had a thorough read of the manual.
As a repacement PCB costs around £200 I was hoping for some advice before calling in a professonal

 

[diamondgas]

There are plenty other things to check before you even consider the PCB.... You'll need to get someone in though IMO 🙁

 

[handsomejackuk]

same problem here, hot water cycles on and off gets hot, then flame goes out and water runs cold. temp sensor on front lcd display is working, as temp goes up and down, and reads very low if clipped off the dhw pipe... any ideas anyone... ?

or has anyone determined the cause of this.