Vaillant 937 whining noise

[Missinformed]

Hi, hope someone can help.
My new Vaillant 937, installed 11 months ago, has started making an annoying whining noise when the central heating comes on first in the morning. This lasts for about 10 mins and goes away again until the thermostat demands more heat. I've experimented by turning the heating temperature flow dial up or down to see if it makes a difference. If I turn the dial down the noise gradually stops, however, when the system demands more heat later on, the noise is back. It only makes this sound when the burner is on and stops when the burner goes off but the pump is still running. Does anyone have any idea what is causing this? It is driving me slightly mad. Many thanks.

 

[Mike Jackson]

Could be a problem with the air gas ratio. You need a RGE with a flue gas analyser to check it and correct it if that is the problem.

 

[Missinformed]

Thank you Mike. I will ask the installer to investigate. What is a RGE by the way?

 

[Mike Jackson]

Registered Gas Engineer.

 

[dancinplumba]

should still be under guarantee

 

[Mike Jackson]

Considering it's 11 months old the air/gas ratio could be checked and adjusted on the first annual service and Vaillant called in if the problem persists.

 

[Brendan Rodgers]

Like they said pal,, CALL VAILLANT,, it could be a few things could that and it dose sound like a combustion problem as the boiler ramps up and down,, dose it do it on ho****er at all?

 

[Brendan Rodgers]

HOT WATER THATS SUPOSED TO SAY,, dont no what happend ther,, i think the system thoght i was giving you my phone number...lol

 

[Missinformed]

It doesn't do it when the DHW is being drawn off, if in fact the noise stops temporarily.
I did have it serviced recently and I thought he would have checked the gas ratio - he had some kind of hand held reader.

 

[Mike Jackson]

A lot of people will just check the CO/CO2 ratio when a check on the CO2 and O2 levels are also required.

 

[Missinformed]

Thank you for all you replies. The installer is coming to have a look next week and I'll let you know the outcome. Typically it's not doing it at the moment, perhaps that has something to do with it being a bit warmer outside?

 

[Brendan Rodgers]

Yes,, if the co2 level is out the ratio could still be acceptable ,,,on zero governor boilers it's vital the co2 is to the book, but still, it should be under garuntee and shouldn't be doing this.
The hand held digi device he had could have been a digital manomitor checking dynamic gas pressure . Give your service man a ring to check cos if it's a service issue it could void you warrantee..
you could have a faulty burner, injector or flue seal by the sounds of it but check service details first..
good luck,

Brendan.

 

[Missinformed]

Thanks Brendan. I don't believe this is a service issue as the noise was happening before it was serviced. I did mention the noise to the installer but I don't think he took much notice and just concentrated on doing the service. He said in it was most likely the cover vibrating (which it clearly isn't!). To be fair,I hadn't monitored it myself at that stage or worked out that it happens when the heating flow temp dial is turned up, so I didn't give him all the info. The boiler is under a 5 year guarantee which stipulates an annual service and if any problems arise an attempt to resolve must be made with the installer before enlisting Vaillant's support. So, hopefully I'm doing everything by the book in terms of keeping within the guarantee.

 

[Missinformed]

Just a quick update: Vaillant came out to investigate, checked gas/ratio levels etc and they were normal although the co2 level was slightly high. However, the main issue seemed to be that the output (28kw) was too high for my house/number of radiators (11) and so he reduced it down (to 16kw I think he said). So far, touch wood, the noise has stopped and the boiler seems to be running more quietly overall. I have to say I am really impressed with Vaillant, they came out the same day and spent ages checking all aspects of the boiler.