What is the cause of a boiler PCB burning out?

FarmHouse_2

In December our boiler melted it's PCB (quite literally). We had the engineers out and a new PCB was fitted and everything tested. All was fine again. Now (February) the same thing has just happened . . . smelt the acrid burning smell and the boiler was humming quietly (even though no heating or water was on!)

I turned it off and saw that the new PCB was also burnt out. A new one arrives today but wanted to find out what could cause this.

I don't understand how anything should actually get to the point of melting (shouldn't a fuse blow first?) and assume that something must be drawing lots of power through the PCB even though everything is off.

Any ideas? I don't want to be fobbed off by the engineer that it is ok as this is expensive!

Boiler is a Worcester and the whole heating/water system was only installed in 2003.

Thanks.

macman

Why is it 'expensive'? The original part and repair should be guaranteed for more than 2 months, so you shouldn't be paying anything.

Owain_Moneysaver

If you / your engineer want an exchange refurbished PCB instead of a new one, try CET Ltd