Replies

1. 
   user-2310254 | Oct 19, 2016 05:54pm | #1

   I have Panasonic fans and used exhaust covers with dampers. I would be concerned that the internal damper would not seal sufficiently and outdoor air might infiltrate into the exhaust line whenever the fan is not on.

   Maybe your contractor is used to the cheap junk exhaust fans that most people install. The Panasonic is an entirely different product.

   On a related note, be sure to use smooth, metal, insulated ducts and ensure that all connection points are sealed.

2. 
   Mark Gardiner | Oct 19, 2016 05:57pm | #2

   Steve: thanks for your reply, my thoughts too. But since I am often wrong additional advice is most welcome.
   Thanks.

3. GBA Editor
   Martin Holladay | Oct 20, 2016 06:06am | #3

   Jeremy,
   For additional advice on duct details for exhaust fans, see this article: Bathroom Exhaust Fans.

4. 
   Mark Gardiner | Oct 20, 2016 07:25am | #4

   Thanks, I missed it during my search

5. 
   brp_nh | Oct 21, 2016 08:33am | #5

   We have Panasonic exhaust fans in our two bathrooms. You're right...the built in fan damper isn't really much of a solid seal, but probably meant more to block large gusts of air.

   We installed these Broan wall caps:
   http://www.broan.com/products/product/09bf95b6-1e3c-4259-843a-d56728dd32ea
   I'd rate them pretty good as they are well made with a solid screen and ok damper. I say ok damper because the weather stripping associated with the damper started to separate and needed replacement (can just use stuff found at local hardware stores).

   To truly seal out cold winter winds, we also installed these:
   http://www.tamtech.com/store/catalogue-name-1/tamarack-cape-backdraft-damper-4
   Our duct runs are very short, so I wasn't concerned about reduced air flow. If you did install these, I think it would make sense to do so in an accessible location, in case they ever need to be replaced or cleaned, but maybe that concern is unfounded.

   I've seen people mention Seiho products:
   http://www.seiho.com/product/index.html
   Looks like the dryer vents have a damper but no screen...and the wall caps have a screen but no damper?

   These look like a decent wall cap:
   https://www.famcomfg.com/featured-products-html/hooded-wall-vent-with-spring-loaded-damper-gasket-and-screen-painted.html

   To more directly answer your question, I would use a wall cap with damper...even at 30 CFM, the fans easily open the wall cap damper.

6. 
   davidmeiland | Oct 21, 2016 09:38am | #6

   I have used Panasonic fans on many projects, and always install Seiho wall caps. Make your duct runs as clean as possible and your fan will work fine.

7. 
   Mark Gardiner | Oct 22, 2016 10:12am | #7

   Brian, thanks for your suggestions, good to know the dampers open easily, I was concerned about that though we are using 6" duct and have short runs.. I have some of the Famco vents on order but I had not come across the Tamarack damper, they look very interesting.

8. 
   cldlhd | Jan 22, 2022 01:34pm | #8

   I've noticed when standing under my bathroom fan, particularly on one of those middle of the night runs us guys over 40 have..., that I feel the cold air coming down on me. My roof vent is a decent one but it's damper isn't airtight and I can understand why because it would likely freeze in the winter with all the moist air that goes through it. But it seems like the ones built into the fan could be a little better and achieving an airtight seal. I thought about removing the one in the fan and putting one in the duct that's in my attic. But the problem is the attic is unconditioned so in the winter it gets below freezing up there. That combined with the cold air coming down from the roof vent makes me think it might freeze shut as well. Any advice?

9. Expert Member
   MALCOLM TAYLOR | Jan 22, 2022 04:36pm | #9

   Cldlhd,

   Tamarack makes very effective inline back-flow dampers. Several builders from New England who post here use them and have never complained about freezing. Situating it close to the fan and insulating the duct would be good insurance.
   https://www.tamtech.com/blog/videos/stop-cold-air-from-entering-through-the-bath-kitchen-range-or-clothes-dryer-exhaust-see-the-cape-damper-in-action-2/

1. 
   cldlhd | Jan 23, 2022 09:31am | #10

   Thanks, just checked them out. I was thinking the same regarding attaching close to the fan, insulating it then burying it in loose in loose insulation to hopefully prevent freezing. I had always used the solid pipe ten wrapped it but when I replaced the fan I put in flexible insulated duct. It looks like tamarack one is designed to have the duct attach by going over it ( just like the fan) so I couldn't attach it directly but I could use a short piece of solid pipe to connect it. I guess I'd try to pop the fans damper out of it's housing so I wouldn't have 3 of them online. Thanks for the link