Replies

1. 
   PatchogPhil | Dec 27, 2009 09:26pm | #1

   Not sure why you need a 'Y'?

   Don't use vinyl clothes dryer flex duct. You want as smooth of an internal surface as possible. Thin wall PVC is best, then galv sheet metal. The galv sheet metal comes in pieces that can make angles from straight to more than 90 degrees. I'd bet you could make that fan line up with the roof vent.

   There is also a corrugated aluminum flex duct (small ribs) that can smooth out an alignment issue.

2. 
   webby | Dec 27, 2009 10:08pm | #2

   We usually use the Broan brand roof vent kits. They come with an aluminized 4 inch vent hose. We have never had a problem with them.

3. 
   Matt | Dec 28, 2009 08:38am | #3

   Jim:

   Use this type of flex duct:

   http://www.antonline.com/p_A048MX-9-GP_507223.htm

   The stuff is much more rigid, retains it's shape, and is less prone to failure than cheap vinyl flex ducting or the tinfile flex duct.

   Here, it is available in big box home stores.

4. 
   Clewless1 | Dec 28, 2009 09:16am | #4

   I agree w/ the other poster ... why use a Y?

   Rigid ductwork is easy. The elbows are adjustable to enable you to line up anything w/ just about anything else. Use two if necessary, but usually if the offset is only e.g. an inch or so, one should do it. Always install w/ the crimps facing down so the condensation doesn't leak out the joints into the attic. Seal the duct well, too (NO GREY DUCT TAPE, though).

5. 
   JTC1 | Dec 28, 2009 09:35am | #5

   The aluminum flex which Matt linked to is good stuff. I can get this product at HD or Lowes locally.

   I get the best performance by not extending the flex any more than needed to make the reqired bends.

   If a longer duct run is neeeded, I will use a combination of rigid aluminum duct pipe and the aluminum flex (Matt's link).

   Seal all pipe joints using the aluminum HVAC tape.

   Jim

6. 
   k1c | Dec 28, 2009 10:12am | #6

   I used left over insulated flex plastic duct from the heating installation with connections screwed, zip tied and taped with foil tape. I stretched it fairly tight so that it is not like a folded accordion inside. I used metal bends.

   Biggest problems for me were using cheap HD roof vent that allowed the water to come in when rare heavy rains bounced off the 4/12 pitch roof. I made bigger roof for the vent with bent sides to solve that problem.

   Second problem is vent fan collecting dust and contributing to noise, and the fan motor bearings burning out. I do admit that kids forget to turn it off and it often runs all day long. I found it impossible to change the bearing with simple tools I have. I am changing burned out Nutone with Panasonic and installing mechanical timer. Hope this helps.

1. 
   JTC1 | Dec 29, 2009 11:46am | #7

   >>....and installing mechanical timer.<<

   That will do it!

   Jim

7. 
   BigBill | Dec 29, 2009 12:09pm | #8

   Go with what kc1 does. I use insulated ducting to minimise condensation. Here we can get water dripping out of the fan from condensation. I've seen sags in the venting collect water and block the exaust air flow.

1. 
   PatchogPhil | Dec 29, 2009 03:59pm | #9

   You can wrap insulation around thin wall PVC sewer pipe. Smoother insides and rigid so no droops or wobbles.