BAXI SOLO 2 60PF fault

[Hawkijo]

My boiler has just started to make strange noises as it switches off.

The boiler generally works fine, but when it switches off, a noise comes from the control box that sounds like a relay switching on and off very fast.
This always starts at the end of the 6 minute pump over-run period and goes on for about 1 minute. There is also a similar sound when it switches on, but then it only lasts a fraction of a second.

A new circuit board was fitted in October 2003 (cost £100 from Baxi) because the ignition coil stopped working.

I'll be grateful for any suggestions
JH

 

[Boilerman2]

Get a Qualified Boiler engineer to check the voltages to the boiler both Permanent Live and Switched Live check between Lives & Neutral AND Neutral to Earth if all OK new PCB (its not done bad 7 years is good for a Pcb on these boilers!)

 

[Hawkijo]

The voltages measured at the terminals on the boiler circuit board are these.

With heating on and boiler alight:
Switched live 243v Permanent live 243v pump live 243v.

With room thermostat turned down so that boiler goes off:
Switched live 210v permanent live 243v pump live 243v

With thermostat still down and at the end of the pump over-run period and at the start of the buzzing:
Switched live 210v permanent live 243v pump live 240 going down to 15v.

During the buzzing period, the pump live voltage rapidly drops to about 15v then slowly down from about 4v to 1v until at the end of approx 1 minute, down to zero and then the buzzing stops.

In all conditions, the voltages between neutral & earth is zero and between earth and live, as above.

 

[Hawkijo]

Boilerman2 was right. It was the circuit board.
We did all the checks recommended and narrowed it down to the boiler PCB. If anyone else is in the same position, I would shop around as I found prices varied from £135 up to £150 although a trade price is probably lower.

My thanks to all who replied, including BAXI engineers on their help-line.

Regards
JH