Extractor fan vents banging

HarrietK · Posted: Sat Nov 11, 2006 8:38 pm Post Subject: Extractor fan vents banging

Hi there

We have an extractor fan in each of two bathrooms recently fitted by our plumber&electrician and when it is off, the slats of the fans bang back in the wind. This constant banging back is really noisy so I am looking for a way of reducing or eliminating this.

It is really cold here as we are in a very windy place, and so just removing the slats would make the bathrooms freezing cold!

Any tips or ideas would be greatly appreciated.

I had thought of putting some sort of pads or something on the slats but not sure where to start with this!

Thank you in advance for your help!

RF Lighting · Posted: Sat Nov 11, 2006 8:52 pm Post Subject:

is it the slats on the external grille that are banging in the wind, or some actually built into the fan?

If it is the external grille you could try changing it to a standard grille, and fit something like this in the ducting, but you may find you still get the same problem if you are in a very windy spot.

If you still have trouble then you will have to fit a fan with a built in electric shutter, such as an Aidelle Icon Fan. Vent axia do them too.

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Jaymack · Posted: Sun Nov 12, 2006 10:53 am Post Subject:

You could try an external fan cowl type, these also have either self-closing slats or a flap; and come in white or brown.
B&Q and Homebase etc. sell these.

Jaymack

JohnD · Posted: Sun Nov 12, 2006 11:11 am Post Subject:

Like this

which is what I use. They have a single large flap under the cover and are somewhat protected from the wind. I live on the coast and it is quite windy.

I hate the ones with little flaps like venetian blinds, they're always rattling, and fall off in bad weather.

nstreet · Posted: Sun Nov 12, 2006 11:23 am Post Subject:

I've siliconed a couple of m10 bolts on the bottom of the flap in the past. This is sometimes just enough to stop the wind lifting the flap but not enough to prevent the fan opening it.

Jaymack · Posted: Sun Nov 12, 2006 12:33 pm Post Subject:

nstreet wrote:

I've siliconed a couple of m10 bolts on the bottom of the flap in the past. This is sometimes just enough to stop the wind lifting the flap but not enough to prevent the fan opening it.

This would increase the air resistance of the fan; and reduce the efficiency: - less air flow!

Jaymack

SparkyMarky · Posted: Sun Nov 12, 2006 1:56 pm Post Subject:

I've got the same problem with my kitchen extractor fan, even though the outlet is sheltered from the wind. I think it's as much to do with the flaps lifting due to the inbalance in air pressures inside and outside the house during strong/gusty winds as the wind actually lifting the flaps. I might try fitting one of the backdraft shutters mentioned earlier and see if this helps, but if it is air pressure imbalance causing the problem then it probably wouldn't help in my case.

During my more creative moments when my engineers head is on I've pondered over the idea of trying to cobble together something using a small solenoid acutator to actually hold the flaps shut when the fan isn't running. Should be easy enough to do in theory, but it's one of the many things I never seem to get around to doing....

Jaymack · Posted: Sun Nov 12, 2006 3:26 pm Post Subject:

SparkyMarky wrote:

During my more creative moments when my engineers head is on I've pondered over the idea of trying to cobble together something using a small solenoid acutator to actually hold the flaps shut when the fan isn't running. Should be easy enough to do in theory, but it's one of the many things I never seem to get around to doing....

There are already fans on the market with solenoid operated grilles, these only open when the fan is energised. You probably know that.

Jaymack

SparkyMarky · Posted: Sun Nov 12, 2006 8:47 pm Post Subject:

Jaymack wrote:

There are already fans on the market with solenoid operated grilles, these only open when the fan is energised. You probably know that.Jaymack

Mine's actually on a cooker hood outlet so I wouldn't need the fan, just the grille. I've seen the fans with built in automatic louvres, but never seen the louvre available as a stand alone item (although I wouldn't be surprised to learn that someone somewhere sells them!). I guess they'd be very similar in design/operation to the control dampers fitted to industrial/commercial building ventilation ductwork.

DIYerHELP · Posted: Mon Nov 13, 2006 9:14 am Post Subject:

We had the same problem and cured it with small amounts of draught excluder strips. Cut a few small strips and stick them to each flap.

Works a treat!

rocky_robin · Posted: Fri Dec 05, 2008 1:10 pm Post Subject:

I know it's about 2 years since this post was created, but to answer SparkyMark's question, you get Anti Back draught dampers on a certain on-line auction site. Clicky

I've got the same problem, but my hob pipe is blooming rectangular! Ggggrrrrr

JohnD · Posted: Fri Dec 05, 2008 3:21 pm Post Subject:

have you got the sort with hanging flaps that look a bit like a venetian blind? they're rubbish, they always rattle annoyingly, and they fly off in strong winds.

I use the cowl vent with a single large flap, and a cowl to reduce wind effects and throw off rain.