Biasi 24S hot water too hot

[UnclePip]

I have a problem with my boiler the Ch works ok but when running the HW I get a reasonable flow rate but it gets too hot. The temp gauge on the boiler goes up to over 100! and then the cut out button pops out. This happens before I can fill the kitchen sink.

I had an engineer here today, he says that I need a new main circuit board which will cost over £400 and that I should cut my losses and fit a new boiler. £2000 !!!!

I had a quick google and seems to me that the heat exchanger might be blocked. Do you think this is likely? Or is it even simpler like a bust thermistor? Presumably the boiler modulates when heating the water?

I found the circuit board available for £120 and even cheaper on ebay. So I think that I am being overcharged. The boiler is about 8 years old.

Anyone know a good plumber in Bristol?

 

[Agile]

Let the boiler cool for a couple of hours and measure the resistance of each sensor. Should be about 13k.

Most likely the HW sensor is o/c.

Most unlikely to be the PCB.

You have an engineer who cannot fix boilers, quotes excessive price and expects you to pay over the odds for a new boiler when all it needs is an £18 sensor!

Tony Glazier

 

[bengasman]

...I had an engineer here today, he says that I need a new main circuit board which will cost over £400 and that I should cut my losses and fit a new boiler. £2000 !!!!

Nonsense, cowboy talk. 99% of boiler problems are economically viable to repair; my whole business is based on this principle. Look at my website if you want more info on repairs.

I had a quick google and seems to me that the heat exchanger might be blocked. Do you think this is likely?

No, only a small chance it's the pcb, and no chance it's a blocked hex

 

[UnclePip]

Thanks for the help.

I had a look inside and found that one of the thermistors was unplugged, So I thought that it was as simple as that, but it turned out not to be,, the boiler still got hotter and hotter. By turning off all but one of the rads I also found out that it does overheat on the CH as well.

I checked the themisors with a multimeter as per the service instructions and they were fine. So I went to the spares supplier around the corner and bought a new PCB, £144 including VAT, no doubt the professionals would have got it cheaper, anyway all working now.

Thanks for the advice, just pleased it was nothing to do with the gas side of things.