Baxi Solo 3 30PFL buzzing noise

[suz82]

Its that time of year again when things make strange noises with the heating!

Our boiler has been fine all summer so I have now determined that it makes a strange buzzing noise when the heating has been on (as apposed to just the hot water). The noise happens only when the boiler has been on then goes off (when room is to temp). Any thoughts on the cause? I'm thinking pcb.....?

Many thanks in advance

 

[Beerlover]

Do you have an Auto bypass valve? it could be that opening on the pump overrun from the boiler. Try opening it 1/2 a turn.

 

[expertgasman]

TRV? When buzzing occurs, try turning off trvs. If noise stops, you 've found the problem.

Is it when boiler is firing? If so may be gas valve "chattering"

Stand by for many more ideas

 

[suz82]

Its after the boiler has been on for a bit, then it switches itself off, then the buzzing kicks in. Its coming from the boiler itself.

Not sure what a TRV is or where it is?!

 

[suz82]

Been doing some research - the TRV is on the radiators ok? These are ok, not making a noise.

Looked in the airer - can't see an auto bypass valve, just the pump and diverter.

No noises coming from the airing cupboard, just the boiler.

 

[expertgasman]

OK, not trv's then. When buzzing starts, drop flap to gain access to thermostat. Turn stat right own. If buzzing stops immediately, then suspect gas valve

 

[suz82]

Thanks - will give it a try tomorrow night and update.

Cheers!

 

[suz82]

So an update; each time the buzzing has started it has stopped when I remove the cover! Another thing I have found is that by switching the fuse off at the wall the buzzing stops. If I switch the fuse back on it sometimes starts buzzing again...

This is quite an intermittent fault and only happens after the heating is on. PCB?

 

[suz82]

Finally been in the kitchen when the buzzing happened- turned the thermostat on the boiler down and it didn't stop the buzzing... Turned the boiler off at the fuse(wall switch) and the buzzing stopped. Switched back on and the buzzing returned.

 

[rojaca]

had a really odd noise on occuring on the pcb on a solo being caused by what I think was a back voltage of a dodgy drayton or danfoss 3 way. caused a really odd boing noise on the board but only when the valve motor was moving over.

btw turning stat down doesn't eliminate pump/circulation noise as pump continues to run for several minutes after blr reaches temp. turning the power off kills both the boiler and the pump (usually).

 

[harold5]

is it a really loud buzzing,? if it is then suspect gas valve .

 

[rojaca]

g.v would have shut off with stat harold

 

[harold5]

sorry , didnt read that bit.

 

[suz82]

I don't think it's the pump-noise coming from boiler (bottom bit) rather than upstairs where the pump is...

 

[suz82]

pcb replaced-all fixed!