Humming noise from Vaillant Turbomax VUW 242/1 E

[dradambbb]

This has recently developed with noise being heard in every room of the apartment.

Symptoms: Turn on CH and let it run - absolutely fine for hours. Then I open HW for a few seconds and shut HW off. Now this combi boiler begins to hum. When HW is turned on the noise goes away until the tap is shut off at which point the noise resumes.

All TRVs are fully open. The DHW diverter valve was replaced about 4 or 5 months ago and the boiler has been faultless until a few days ago.

I've searched this forum for this topic without finding a conclusive explanation. My neighbour who is an experienced Vaillant adoring fitter says he's not experienced anything like it. So I'm welcoming the input of the wider community.

Thanks,
Adam

 

[Agile]

My neighbour who is an experienced Vaillant adoring fitter says he's not experienced anything like it. So I'm welcoming the input of the wider community.

Thanks,
Adam

So he is not experienced after all.

Boiler noises can be caused by many different situations and a competent boiler engineer would be doing a few simple tests to see what is the cause.

Who changed the diverter valve? Thats unlikely to be the cause though.

Tony

 

[namsag]

You will notice Agile slags the guy and says simple tests will tell you what the prob is but doesnt mention what these are , i wonder why.
Although the noise maybe heard by the boiler it prob has nothing to do with it .
It could be a faulty tap washer/faulty stop cock/faulty ball valve somewhere else on the system causing a vibration through the pipework that is amplified by the boiler.

Or perhaps Agile will let us in on these secret simple tests

 

[dradambbb]

Thanks for your replies. So far I gather that it can be anything and everything. Any suggestion for practical diagnosis steps one might take to reduce the set of possibilities?

One thing I've read is that one could try shutting off all TRVs to see if makes a difference.

I've also read that by changing the pump speed it is possible to work around the problem but AFAIK the pump on this model is not adjustable for speed.

I could get the pump and/or the diverter valve replaced but that is not fault investigation as I know it.

Adam

 

[Agile]

Or perhaps Agile will let us in on these secret simple tests

I would have thought that with all your years with BG you will be as familliar with what to do as I am but you dont list them either.

From what he says it sounds like a hydraulic resonance initiated by an operation of the diverter valve.

Listening with a mechanical stethoscope might help to identify the location of the source. Curing it might be another matter.

It may be possible to reduce it by SLIGHTLY closing the CH flow isolator under the boiler.

Tony

 

[namsag]

There you go again ,mechanical stethoscope . Why dont you just say a big screwdriver placed to your ear.
Thought i had gave him a list of the most likely things it could be.

Pray tell when was the last time you had a divertor on a 242 give off hydraulic resonance.

 

[Agile]

There you go again ,mechanical stethoscope . Why dont you just say a big screwdriver placed to your ear.

Because I like to use the proper tool for the job!

See:-

http://www.saxon-motorsport.co.uk/i...pID=22&zenid=d775b560a25666ff5f8c6360e0be0129

 

[namsag]

Must have been another Agile then that suggested using a screwdriver on this very site then. I am sure your customers must be very impressed when you take that out of your box.
So how many vailants have you diagnosed with a faulty divertor with that device then??

 

[dradambbb]

Now now boys, let's not get into scrap

Placing a knife (or long screwdriver as you say) against the various components to check-out for the source of the resonance has been tried. It doesn't appear to be the pump but could be the diverter - it's a bit harder to get to with the "stethoscope".

As for tweaking the CH water isolator, that's worth a try.

 

[Agile]

I only suggest a screwdriver as a listening stick to a DIYer who is unlikely to have the correct tool unless he is a car enthusiast.

They can get into places the screwdriver cannot reach.

I have never had to deal with a noisy 242 yet and I dont think its the diverter itself either!

Tony

 

[namsag]

So basically then you just thought you would slag the guy who actually looked at it and try and sound clever when infact you are guessing and have not got a clue .
I am sure the guy who looked at it would know where to stick your stethoscope

 

[Agile]

The plain fact is that this CORGI installer was unable to diagnose the cause of the problem!

I expect that I could identify it and I would hope that you could as well.

Using the correct tool means that I would have a headstart though!

Tony