A few months ago I had the boiler flue to my Ideal HE12 condensing boiler replaced with a high level flue (ideal V3 flue) due to having a conservatory built. This was carried out by a Corgi registered plumber. Since it has been fitted whenever we have any strong wind the boiler vibrates and sounds as if it will explode and has to be closed down.He has been back but cannot find anything wrong with the fitting of the flue. He says he will come back again and have another look so was wandering if anyone could suggest what is going wrong.

Dave, August 2009

It might well be Acoustic Resonance in an Open Cylinder - see wikipedia article...

http://en.wikipedia.org/wiki/Acoustic_resonance

When the boiler is on, a fan will be blowing the exhaust gasses through the flue - certain wind speeds across the face of the flue opening may be turning your new chimney into a musical instrument - like a didgeridoo.

If you can fit some kind of wind-baffle some distance from the flue outlet, so as not to interrupt the gasses coming out but to divert the wind's airflow away from the flue's opening the change may stop the resonance.

Wait until it happens again and get out there with a square of stiff board - see if you can make the noise stop by diverting the wind a little bit but don't cover the flue.

Peccavi, August 2009