faulty worcester 24i combi

[wozza191]

hi

the fault i have is the fan stays running after the demand for hot water or heating has stopped it says in the manual it should stay on for up to 4 mins but this stays on until you turn it off from the mains.can anyone help please


thanks

 

[ollski]

The fan? or the pump?

 

[wozza191]

its the fan that keeps running

 

[ollski]

Bypass closed?, main thermistor maybe. On a 24i junior the fan runs for about 30s or until the main flow temperature falls below 80 deg.

 

[wozza191]

hi
when you say thermistor is that the overheat thermistat you refer to the model is a 24i RSF on LPG

thanks for your help

 

[ollski]

I was thinking of a 24i junior but the same applies on this one, it is the ch thermistor which controls the overrun.

 

[nickso]

its the pcb that opens and closes power to the fan though, it could be faulty.

 

[Agile]

If you turn on the power to the boiler when its cold, does the fan run immediately if there is no demand for heat?

Or does it only run after there has been a demand for heat?

Tony

 

[wozza191]

hi
it runs after the demand for heat but then will not stop untill you turn the boiler off at mains again

 

[Agile]

The sensor may be showing an incorrect resistance.

Can you measure the resistance cold?

I think it should be about 25k ?

Even if it were correct when cold it might still not be following the correct curve.

Tony

 

[wozza191]

hi Tony
thanks for your input i can but the said boiler is down north wales in my static caravan,do you think its worth me getting one and trying it

thanks again Warren