Extractor Fan Exhaust Dilemma

[fullern]

Hello all,

I live in an old Cornish cottage and have just got round to installing an extractor fan for the bathroom.

It is an in line fan that is situated in the loft above the bathroom and is fixed to an old chimney breast that runs up through the house and through the bathroom.

The dilemma I have is that we do not have any soffit through which to exhaust the fan up in the loft. In addition to this the fascia is pretty much stuck right onto the granite wall resulting in no over hang, and the fascia itself is too narrow to fit the vent on.

So my options are;

1. Pay another £100 for a roof cowl kit and potentially pay someone to fit that

OR

2. I came up with the idea of using the old chimney breast. My plan is basically to knock/chisel a hole large enough for the duct, and then run it to the top of the chimney stack (so approx. 3m in length) and either vent it out the top of the chimney stack or off to the side. I would also make sure that the hole I cut in the chimney breast was was sealed with silicone or expanding foam or something similar to stop any water ingress.

Thus saving me over £100!!

I would appreciate it if anyone could point out any glaring problems with this that I in my ignorance am unaware of.

Oh and the fan is currently disconnected so don't worry its not venting into the loft!

Thank you for any points on this in advance.

Nick

 

[Beefpotnoodle]

I personally wouldn't go anywhere near the chimney, just straight out the roof. (even if the motor can push x amount of air y distance horizontally and z distance vertically) I've seen it first hand in a new build with extractor, the pipe is cold, you'll be pushing warm moist air through it. Some of the air will cool, and moisture will form on the inside. That leads to mold, or water droplets coming back down the pipe, yes theres a flap to stop it coming all the way, if it works effectively!
Neither sounds appealing to me