Attaching duct to in line fan

[zikkimalambo]

Hi All,

I was up in the loft yesterday (trying to see if I had a water leak which might explain the damp that's appeared downstairs. Didn't find anything, I think it must be coming up from below :=((

In the meantime, I found myself puzzling over the in line fan which some builders recently fitted. (part of a showerlite fan).

I couldn't work out where the outlet was going - turns out they have lifted the lid on the cold tank and poked the end of the ducting in there (where it has subsequantly been squashed. I presume thay were working on the theory that the tank had an overflow pipe (somewhat smaller than 100mm dis!) going to the outside world, so the air would go out there.

I reached round and touched the fan (not screwed to anything, and the flexible ducting fell off!

The fan unit is like a piece of pipe 100mm dia and maybe 80.. long with a fan in the middle. They had attached the ducting with a single nylon tie round the outside of the ducting.

I may get them back to sort this, or I may just decide it's easier to do it myself. Either way, what is the correct/better way to fix this ducting?

[The Natural Philosopher]

Strictly it should exhaust to the outside world..under the eaves through a soffit is good. Exhaust flanges are cheap to buy..

Tie wraps are normal.

However long duct runs don;t do a lot for the action, and many people exhaust straight into the roof space if its well ventilated.

[John Rumm]

Duct tape.

The venting really needs to go outside as well.

[zikkimalambo]

Yes, i'm aware of that, and it would have come with the necessary kit, I am a bit p*ssed off with the builder!

Having had a look at the instructions for one of these, tie wraps do indeed seem to be normal, but it seems a bit inadequate on something that doesn't even have flanges for the tie wrap to sit behind.

[Andrew Gabriel]

When I've bought the ducting by itself, it usually comes with a couple of giant jubilee clips, although I would have thought a tie wrap should work. They're harder to do up tight without the special tool. Make sure you don't crush the flanges and foul the fan blades.

For long runs, I have always assumed the rigid ducting would work better than concertina by encouraging laminar rather than turbulant flow, but I've never actually put it to the test.

[nightjar]

I use Jubilee clips. No 5 clips would be right for 100mm ducting.

Colin Bignell

[Lurch]

On 14 May 2007 04:49:58 -0700, [e-mail] mused:

Why not? What pressure do you think the fan is pushing out? I've never had one fall off when secured with a cable tie.