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Back Draft Shutters - does a good design exist?

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RichardG

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Our house has 360 unobstructed views which means we get the wind no matter what direction it’s blowing. We also have 3 vent outlets from bathroom, toilet and kitchen. I have yet to find a back draft shutter that works, is quiet and lasts for more than a few years.

I started off with the 3 horizontal flap style on the outside wall of the vent. These kind of work but are continually flapping in the wind and eventually one of flaps blows off in the wind.

I then tried the internal style that has two half round flaps and a spring. These are probably the best so far but the spring fails after a year and then means I have to crawl around the loft or lift floorboards to replace.

I then tried the internal single flap style which has an offset pivot. These just continually slap open and shut and are driving me mad...

I’m just about to try one of these

https://www.extractorfanworld.co.uk/4-inch-no-resist-back-draught-grille---brown-3458-p.asp

But though I would ask the wise folk here for any suggestions.

Thanks


Richard
 

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I live in a windy place too. 30km/hr at the moment, going up to 80 on some days, then storms over 100. I have a couple vents that make noise and one has broken too. So I understand your frustration. Have you considered a motorized intake / exhaust damper? It opens when the appliance is powered up and closes when it is off. You'll need an electrician to wire them in if you aren't qualified.

https://www.wayfair.ca/appliances/pdp/b ... d=18526081

https://www.aliexpress.com/item/3280368 ... lsrc=aw.ds

Pete
 

RichardG

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Inspector":23srsnv0 said:
I live in a windy place too. 30km/hr at the moment, going up to 80 on some days, then storms over 100. I have a couple vents that make noise and one has broken too. So I understand your frustration. Have you considered a motorized intake / exhaust damper? It opens when the appliance is powered up and closes when it is off. You'll need an electrician to wire them in if you aren't qualified.

https://www.wayfair.ca/appliances/pdp/b ... d=18526081

https://www.aliexpress.com/item/3280368 ... lsrc=aw.ds

Pete
Mmm, hadn’t thought of an actuator driven one. Not sure if I would trust a cheap one from aliexpress though, I’d want to see a CE certificate. I will explore this idea further .

Thanks.
 

RichardG

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sunnybob":tk04gjrq said:
easy peasy.
Use the normal louvre face plate, but then over the top of that fix a downward facing cowl used for tumble dryers.
Like this
https://www.amazon.co.uk/Tumble-Dryer-V ... B01AV9MZES
My parents had one of these over the vent that was installed when a gas fire was fitted, it was quiet but not very effective at stoping the draft. However, I’m thinking I’d rather have a draft than flap, flap, flap....
 

sunnybob

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RichardG":2ooab718 said:
sunnybob":2ooab718 said:
easy peasy.
Use the normal louvre face plate, but then over the top of that fix a downward facing cowl used for tumble dryers.
Like this
https://www.amazon.co.uk/Tumble-Dryer-V ... B01AV9MZES
My parents had one of these over the vent that was installed when a gas fire was fitted, it was quiet but not very effective at stoping the draft. However, I’m thinking I’d rather have a draft than flap, flap, flap....
I thought the idea was to NOT stop the draught? :shock:

I have a 4" extractor fan in an upstairs bathroom, and from there you can see to the horizon in 2 directions. The flappy thing drove me mad so I removed it and put fly screen mesh across. Which was a failure because then the wind howled in. So I put one of the dryer vent covers over it. This worked well untill I realised there was no air movement when the fan was on. Removing the vent showed that sparrows had gone up under, bitten through the fly screen mesh, and nested in the tunnel (hammer) (hammer) (hammer)

So now I have fine steel mesh across the hole and the dryer vent over it. It is very effective. No noticeable draughts whatever the wind is doing, and the nearby mirror loses its steam coating in seconds after turning the fan on.
 

RichardG

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They’re so cheap I’ll give them a go and I prefer going up a ladder than crawling round in the loft, so double win.

Thanks.
 

HJC1972

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I have just fitted the airflow Icon fan extractor fan in my bathroom. I fitted it in conjunction with the same back draft shutter in the opening post. Regrettably, the icon fan’s iris is already not closing fully once the timer module has shut off the fan. I’m awaiting response from Airflow but given the current state of everything I’m not holding my breath. The back draft shutter does seem to work ok as there’s little draft coming through the partially opened iris on the fan.

I also replaced the irritating three flap fan on our cooker extractor yesterday with one of the single flap types that has a downward facing cowelling over the top. I was disappointed to see it start flapping straight away in yesterday’s wind. However, I small strip of lead glued to the inside edge has helped reduce this. Not enough to completely stop it but it’s better than the previous three flap thing. I may increase the lead to make it heavier still and see how that works.
 

sunnybob

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gluing lead to the shutter will stop it opening at all defeating the object of the vent. There's a reason the flap is made so light.
 

Mark Hancock

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sunnybob":vnmuwt6i said:
gluing lead to the shutter will stop it opening at all defeating the object of the vent. There's a reason the flap is made so light.
Not if you attach the right amount of lead. I used this solution on the kitchen vent flap and it has worked a treat.
 

RichardG

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So it does appear that there is no perfect design. The airflow fan looks like the best attempt if you can fit it, unfortunately 2 of my fans are inline as they are over a shower..

I’ve also now been pointed towards these.

https://www.amazon.co.uk/Return-Ventilation-Extractor-Backdraft-Shutter/dp/B077PSBDVN

It uses a piece of thick polythene to cover the vent. Relies on the outside air pressure to hold the polythene against the grill and the fan to blow it out of the way. Very quiet apparently....

I may have to do a field trial of this and the other one I found plus sunny bobs suggestion of the cowl and see how I get on.
 

HJC1972

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sunnybob":2p61543u said:
gluing lead to the shutter will stop it opening at all defeating the object of the vent. There's a reason the flap is made so light.
Nonsense. Works perfectly well in fact. The right weight of lead is important of course. I’m not suggesting you glue a hole pack of flashing to it, just enough to weight it slightly. The expelled air is much greater than the force of the outside air lifting it so it’s not difficult.
 
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