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Kitchen Exhaust Hood Leaky

Hi everyone

I recently built my new house and installed a GE Profile Chimney Hood - we love the hood in terms of function and appearance but unfortunately, there is significant cold air infiltration from it...

I think that the cause is two-fold - we have a Broan 643 8" damper that doesn't appear to be the best in terms of staying closed, particularly in even moderate wind...

In addition, we discovered once the house was framed that the 8" round ducting was too large to fit in between the ceiling joists directly over the hood (the space was a little over 7", if I recall correctly)... as such, the builder recommended that we go out into the garage (unheated) which is directly behind the hood's location... so the ducting goes up the wall, turns 90 into the wall, goes about 4 ft, turns 90 to the left and goes out of the house after about 6 or so ft...

The ducting has no insulation around it, other than a drywall box built under it to protect it from the garage below... otherwise, it is completely open to the unfinished space above the garage...

Some have suggested insulating around the ducting but others have said there would be no benefit since it's 100% inside an unheated space...

Others have suggested possibly re-routing the ducting so it doesn't go into the garage but instead into the ceiling and turning to immediately out of the house after 6 ft... doing this would require going from 8" round to 7" round... GE says that it needs a 8" round duct but I am wondering how stringent this requirement is... while it's not ideal, perhaps it would be OK especially since we'd have one less 90 elbow and less straight run ducting compared to now?

Any suggestions on how to best address this?


I tried attaching a picture of what the ducting looked like prior to the drywall installation around it... but the site reported that it was not a valid image, tried both PNG and JPG

Re: Kitchen Exhaust Hood Leaky

I would have no problem reducing the vent from 8" to 7". Then you wouldn't need to go through the garage.

But my question is: why do you have only 7" between the joists over the vent?

To send a photo, upload it on a host like photobucket.com and give us the link.

Re: Kitchen Exhaust Hood Leaky

I'm not quite sure why there is only 7" between those joists, the only thing that I can think of is that it's because that's how the measurements worked out?

The house is 38" wide and the hood is mounted on a wall parallel to the joists

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