wrote in message
oups.com...
DIYer here, researching the feasibility of installing my own kitchen
exhaust fan over a gas island cooktop.

I'm curious about connecting duct to a roof mounted fan on a pitched
roof. The sleeve on the fan is going to be entering the attic at an
angle. What's the best strategy to route the duct to meet the angle of
the sleeve? I can't put the fan directly over the opening. I have to go
over a couple of joists and higher up on the roof. Can I just come out
perpendicular from each opening with two short pieces of duct and an
adjustable elbow at the end, point the 2 elbows at each other and do a
straight run between them?

That's about it. I assume that you don't have to go through any joists or
rafters, just above or below them. Elbows add to the effective length of the
duct so you need to take that into account when sizing the fan.

I'm going for the Fantech RE model. Any opinions there?

Fantech makes a very good product.

Where's the best place to put the backdraft damper? Seems to me near
the end of the run, close to the roof. This way there's less external
air in your duct.

I've always seen backdraft dampers on the intake side. Check out
http://rewci.com/416splobada.html for a spring loaded one.

Am I dumb thinking I can do this myself? A dedicated circuit is already
in place so it's just duct work and installing & wiring the fan. I'm
not seasoned handyman but have a good track record so far with
construction and minor electrical.
Thanks.

Definitely has DIY potential but I'm always leery when it comes to cutting
holes in my roof. You need to make sure that it is flashed and sealed
properly or else...

You also might break a shingle or two so it is helpful to have some spares
around just in case.

-al sung
Rapid Realm Technology, Inc.
Hopkinton, MA