Insect screen mesh for vent fan outlet

In message , AnthonyL writes

Surely if it is *flapped* they could only get in by flying up wind? Unless you want to keep them in the house?

On a shower fan? Well it might but it'll take a while, unlike that on a tumble dryer...

Ebay is often a good place for small pieces of something. Eg 1 x 1.2 m for £1.79 delivered

Or stainless steel 9" x 9" for £5

Owain

Cannibalise a kitchen plastic sieve, but don't tell SWMBO! "No dear, I don't know where it is. Are you sure you didn't put it in the bin?"

He's looking for about a foot square of the stuff not a 5M roll.

Every flapped outlet I have seen is close enough fitting to prevent insects flying in. Perhaps they'd be able to crawl in but no houses are hermetically sealed (something you'd need to keep ALL insects out).

My soffit vent has a mesh insert - something like this:

Can't really see the relevance of a soffit vent mesh to an extractor fan. Very different functions!

Tim

Well, it stops things nesting there...

And last year I had a bird nesting in my extractor fan vent. It's no longer used and was plasterboarded over on the inside, but not sufficiently meshed on the outside.

I just discovered the inside bit today and it should be getting foamed up later this week.

Owain

I was surprised how much putting this stuff over a fan outlet reduced the flow when I put a fan in to keep my workshop cool many years ago. Maybe this is why many do not have it these days. On my air bricks I used some small sized expanded ally mesh which appeared to have been anodised. Yes it had to be cut and clamped in little frames, but seems to have survived for many years.. I think originally it came from Wickes or however one spells it. Brian

No the vent might be needed to be open with no fan running at times. IE ventilation but no fan. Brian

And how are they going to get past the flap? Mesh is absolutely fine for a diffusion vent but will dramatically impair the function of a forced flow fan if one tries to use a mesh small enough to keep insects out.

Tim

What flap?

On 30-May-16 9:24 PM, soup wrote: ...

The standard for stopping flying insects getting into water supplies is an aperture no larger than 57 microns. You must have seen some particularly well fitting flapped outlets.

The mesh I use on insect screens for water supplies has only 40% open space, so the screen needs to be 2.5 times larger than the cross-sectional area of the pipe it is fitted to in order to maintain full flow rates.

From the OPs first post: " which came with a nice but unmeshed flapped outlet".

Tim

I tried Ebay - honest - never came up with anything as handy as this - thank you.

OP here - being lazy the existing outlet, already in situ, has the broken mesh and no flaps and I was simply going to replace the mesh. No idea how it comes to be broken.

The new fan comes with a flapped outlet which means I have to remove the whole of the old outlet, not just the grill, and then no doubt find some silly issue with where to fasten the new outlet.

A bit of nice mesh should take minutes, the latter, with my luck and lack of skills, likely to take a whole morning.

Sorry for any confusion though if you read the OP it is as I said.