Island hood duct installation


  #1  
Old 04-08-18, 07:17 AM
T
Member
Thread Starter
Join Date: Apr 2018
Location: United States
Posts: 2
Received 0 Votes on 0 Posts
Island hood duct installation

New poster here ... with a ductwork question.

In our kitchen reno we are installing an island hood. It uses a 6" round duct. The only workable way to run the ductwork is to transition to 3-1/4 x 10 and go across the ceiling to the nearest exterior wall. There is an open bay and the joists run the way they need to in order to do this. Here are the issues:

(1) To get into the bay I need a slight -- maybe 3" -- offset from where the duct comes up in the back of the 10" x 10" hood column. I'm pretty sure there is room to do the offset then go to a 90 degree 6" round to 3-1/4 x 10 transition. What I'm not sure of is the right piece to do this. HVAC supply house suggested a short piece of flex duct but the manufacturer says "Always use rigid type metal ducts only. Flexible ducts could reduce airflow by up to 50%." Can this be done with one of the 6" adjustable elbows, like this one? https://images.homedepot-static.com/...e6-64_1000.jpg

(2) At the outside wall the bay I am in comes out under a steep eave (slope probably close to 12/12). It will be a significant challenge to install the backdraft damper (looks like https://images.homedepot-static.com/...49-64_1000.jpg), but it may be doable if I cut the hole in the trim large enough to insert the damper at an angle. It will also be a challenge to mount it with screws since I can't really get the tools up under the eave, and also the larger hole will reduce the area the flange covers. I can imagine going up through the roof but that would also be a major challenge since the attic area under that steep section of roof is totally closed off and inaccessible.

Ideas on addressing either of these issues would be very helpful, thanks!

Tom
 
  #2  
Old 04-08-18, 04:19 PM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 25,560
Received 966 Votes on 887 Posts
1. Steel, adjustable elbows can be used so if you can make it fit that would be the easiest solution.

2. Can you cut in or install an access to the attic area above the kitchen? Running the vent straight up and through the roof would be easy.
 
  #3  
Old 04-08-18, 04:38 PM
T
Member
Thread Starter
Join Date: Apr 2018
Location: United States
Posts: 2
Received 0 Votes on 0 Posts
Thanks for the ideas. I think the elbow will work but I will have to try one to be sure.

As for the vent ... this afternoon I tried drilling a 1/4" hole as low as I could on the inside of the wall, right above the top plate. It came out only 1" below the roof boards -- the roof drops so much across the thickness of the wall that there is no way to vent it through there. So I think I will have to go through the roof. That to me is not DIY so I need to find someone to do it. I can't go straight up (would go through a room) but I can go across and up by cutting an access panel in a knee wall in that room.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: