Vaillant Ecotech Plus 415 Conventional boiler “bass noise”

[confused56789]

Hi

Have been having issues with a bass noise that my boiler has been making ever since a new PCB and sensor was fitted last week.

Video shows the slight noise as it fires and then at about 18 seconds in, the noise starts again

https://youtube.com/shorts/GQuwzE7a6C0?si=pWnOQv8kc23wIdkP

These parts were fitted under a service contract with Homeserve due to issues with boiler not staying on and it has resolved that issue. However this “bass” noise started even when the engineer was here when he cycled the boiler after fitting the parts but I thought he was just fine tuning something.

It has never once made this noise before in the whole 14 years we have had the boiler.

I called them back and was told (same engineer) that it may settle down but that they could change the fan and gas valve. But then this plan was swiftly aborted as the cost of these additional parts would push the job into “beyond economical repair”. I have been trying to decide what to do as can’t afford a new boiler right now.

The engineer reckons all the readings were fine when he tested it after fitting the parts. He didn’t do any further tests when he came back.

This noise was only occurring intermittently when the boiler fired up. This morning it is even more frequent and louder …and continuing beyond the initial fire up too.

My thoughts are this may be that something hasn’t been adjusted properly (fan speed/combustion?) and that new parts may not be needed at all. Should I call them back again and insist on 2nd opinion?

 

[Razor900]

That's combustion related. Did they leave any readouts with you?
Call them back out. If it's not burning right it could be a CO risk

 

[confused56789]

No readouts.
Funnily enough he asked me before he left "you do have a carbon monoxide detector right?"
Almost like he was concerned. Wtf?
I don't have one. Was planning on getting one

 

[CarloHeatingEng]

A new bass noise straight after a PCB and sensor change is worth treating as a combustion issue until someone has taken flue gas readings. Ask them for those figures in writing, before and after the parts went in. If the readings were fine there'll be a record of it, and if there isn't a record then nobody actually knows.


Ask them to confirm the board was coded to this exact appliance too. A wrong appliance code can put the fan speed out, which gives you a noise you've never heard before and poor combustion together.


And ask when it was last properly serviced. At fourteen years a heat exchanger that wants cleaning can do this, and that's a long way from fan and gas valve money.


I'd switch it off and get them back rather than run it and see. A CO alarm isn't cover for this one, though you should have one in regardless.

 

[confused56789]

Thanks for the help. Agree that the age can cause noise re: heat exchanger. Its just the fact that it started only when they changed the PCB. Which points towards it being that and not some other issue

 

[CarloHeatingEng]

Fair, and the timing does point at the work. Worth knowing it isn't always the new part itself though. Opening a boiler up disturbs things, and something that was marginal before can stop being happy once it's been moved about. That doesn't mean the board's wrong or that anyone's done a bad job.


Either way it's on them to come back and look. Their work, and the noise started while he was still stood there.