I put in a new 6" duct from a 900mm cooker hood to outside and fitted a multi flapped wall vent cover like this one http://www.tlc-direct.co.uk/Products/BGBD6W.html
It flapped like mad in any sort of wind at all, I tried damping it with draught foam and although that made the sound less obtrusive, it wasnt a fix.
6" duct into a big hood space is amplifying any sound, even road noise when its on the side at the back of the house 100ft from any traffic.
I then bought a 6" Cowled vent like this one http://www.screwfix.com/prods/14789/Heating-Cooling/Ducting/Manrose-Square-Brown-140mm-Cowl-Vent
But that was worse, the wind gets under the single large flap and it then acts like a reed in a kids whistle!
I tried damping it down with a weight and even tried angling the flap so the weight pushed down rather than just adding damping. Still flaps when the wind is just gentle.
So my last attempt will be a 6" inline backdraught shutter like this one http://www.alertelectrical.com/Fans...le-Ducting/150mm-Backdraught-Shutter-1232.asp mounted in the 300mm of duct from the hood. I will keep the cowled external part that I have and remove the flap from it.
Has anyone else managed to crack the problem?
I am hoping that inserting the flap inside the tube will stop the wind from getting under the lips and flapping it. I have to assume the spings on these are set so on low settings the fan can still open the flaps.
It flapped like mad in any sort of wind at all, I tried damping it with draught foam and although that made the sound less obtrusive, it wasnt a fix.
6" duct into a big hood space is amplifying any sound, even road noise when its on the side at the back of the house 100ft from any traffic.
I then bought a 6" Cowled vent like this one http://www.screwfix.com/prods/14789/Heating-Cooling/Ducting/Manrose-Square-Brown-140mm-Cowl-Vent
But that was worse, the wind gets under the single large flap and it then acts like a reed in a kids whistle!
I tried damping it down with a weight and even tried angling the flap so the weight pushed down rather than just adding damping. Still flaps when the wind is just gentle.
So my last attempt will be a 6" inline backdraught shutter like this one http://www.alertelectrical.com/Fans...le-Ducting/150mm-Backdraught-Shutter-1232.asp mounted in the 300mm of duct from the hood. I will keep the cowled external part that I have and remove the flap from it.
Has anyone else managed to crack the problem?
I am hoping that inserting the flap inside the tube will stop the wind from getting under the lips and flapping it. I have to assume the spings on these are set so on low settings the fan can still open the flaps.