Ariston System boiler loud buzz

[JonnyGrew]

The hot water ignition seems fine - no noises. However when the CH fires up there's a really loud buzzing noise. This is short to begin with but as the boiler heats up it seems to go on for longer. It trips the system when it buzzes for more than about 15 seconds and I need to reset it every now and again.

I've been informed that it sounds like an AC current is passing though the PCB and that I should replace it.

Does this sound a plausible problem?

Cheers

 

[Agile]

Its likely to be a fault on the smoothing circuit of the PCB and then it applies DC with a 100 Hz ripple to the modulating coil on the gas valve.

This produces a 100 Hz buzz which gets more pronounced as the gas valve modulates down.

You will get the same effect if you turn the hot water tap onto a very small flow rate.

Tony Glazier

 

[JonnyGrew]

cheers Tony,

I'll replace the pcb then!

As it's a system boiler, not a combi, I don't get the same effect by turning the hot tap on a little as we've a hot water tank.

Thanks for the info and advice

 

[Agile]

Sorry, there are so few Ariston system boilers I did not accept that it was not a combi!

Please dont blame me if its not the PCB at fault I am only making the suggestion at a distance based on your description of the problem. I have not tested your boiler myself.

You could try listening to the mod coil and see if that seems to be the source of the buzz.

Tony

 

[JonnyGrew]

not to worry, I wouldn't blame you!!

I'll post up what the problem was once I've tried to replace the pcb - and it's hopefully sorted!!

A plumber mate of mine phoned some kind of help line and held the phone to the boiler to give the operator an idea of the noise. His imediate reaction was that the pcb needed replacing.

Will let you know.. it's on order and I expect it in the next 2 weeks!!

 

[Softus]

Sorry, there are so few Ariston system boilers I did not accept that it was not a combi!

Ariston ® ?