Non Return valve for extractor fan

A few years ago, I refurbished my bathroom. When fitting an extractor fan, i was able to get a non return vale for the ducting. Does anyone know where these can be purchased on line?
Many thanks
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Paul Neill wrote:

Try www.bes.ltd.uk > Installation > Ventilation > Ducting & Accs. = Dampers.
Items 15665 for 100mm duct (2.75), 15666 for 125mm (3.19) & 15481 for flat channel ducting (1.40). All plus vat & 5 delivery
--
Toby.

'One day son, all this will be finished'
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

flat
How about the gravity flaps e.g. 13629 - these look very non-return.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 9 Jan 2004 10:47:01 -0000, "David W.E. Roberts"

Fantastic suggestion, I've fitted loads, no problems at all and its a lot easier than in line backdraft shutters.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Let me know how you get on - could be an upgrade for my fan :-)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I have recently had an extractor fan fitted in my bathroom. The house is quite exposed to the elements and the fan is getting a fair draught through it.
Could you tell me if these have any impact on the performance of the fan whilst it is extracting?
Also which type are they is the back draft protection from the outside grill or a one way valve type thing in the pipe? Which is better and why?
Thanks

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

I would go for the gravity grille option, you've got to fit a grille anyway when you're installing the fan so there isn't any extra work involved. They are also available off the shelf at wholesalers and diy stores. If you went for the backdraft shutter option you have to ensure it is a totally airtight seal within the duct which can be tricky and can also make it more difficult if you have to remove the fan for repair. Also you would struggle to find any off the shelf, they'd have to be ordered from somewhere. Most 4" fans have a fair bit of draught coming through if there is just a standard open grille on the outside, changing it for gravity is an easy swap and should solve the problem. With regard to performance unless the fan is directly in line with a huge gale it shouldn't be a problem.
SJW A.C.S. Ltd.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.