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Saving a bit of heat.

I live on a hill top. Brutal wind. Not so in the valley. Anyhow, all night long I could hear the flapper plastic door/valves swing open sucking out heat from my bathroom vent fans. (When the fans were off).

So I put in 24vac power dampers on relays activated by the bathroom fan on 120v. Problem solved. Prior to that I had 2 four inch holes in the house venting heat into the outside. It has probably been covered before. If so, I apologize.

Now, when the bathroom fan runs, unimpeded exhaust to outside. Fan off = sealed drum tight.
On my 3, or 4 th year. Maybe more. Works great in a tight house. ICF construction with radiant floor heat.

Thank you,


  • GordyGordy Member Posts: 9,523
    Great idea. Also keeps precipitation out (blowing snow, or rain) on the roof type vents when not in use.
  • IcarusIcarus Member Posts: 105
    Most modern bath fans have a damper built into the fan housing. The terminal cap also has a damper. While I like the concept of a powered stack damper, the headache factor might not be worth the effort?

  • Larry WeingartenLarry Weingarten Member Posts: 1,799
    Hi, I installed just that motorized damper on my kitchen exhaust about 15 years ago and it still is going strong. Perhaps I don’t cook enough :D
    Yours, Larry
  • GordyGordy Member Posts: 9,523
    What’s happened with one bath fan a couple times, is snow blows in the exterior housing. Lays in the duct, and doesn’t melt. Until you take a shower with the fan going. The secondary flapper is open the snow melts, and runs all over the bathroom floor.
  • mikeg2015mikeg2015 Member Posts: 1,178
    Mine are under a deep soffit so haven’t noticed. I wonder if vents on a wall face get more updrafts and flip them open?

    I did like the central exhaust fan design better.

    When in stalled central air, I almost went with mini splits for the 4 main bedrooms and use a continuous ERV to vent & pull conditioned air into the bathrooms.
  • pecmsgpecmsg Member Posts: 1,425
    Be careful with a ICF sealed home that its not too tight.

    Every home should have a complete air change every 6-8 hours too stay healthy and exhaust indoor pollutants!
  • TAGTAG Member Posts: 213
    That's a good idea ..... my last two projects have used the external mount Fantech unit -- that still requires a damper .... but the units fan design limits the backflow.

    On a big kitchen exhaust -- it's a very good idea .... as long as you can clean it
  • DaveinscrantonDaveinscranton Member Posts: 3
    These are under a 4 foot roof overhang. For whatever reason, nothing was keeping the vents (original) closed in the wind. I think it is a fluke situation of the house orientation and prevailing winds.

    Works great. I had most of the parts so no big expense. Maybe 4 hours tops in the attic. Maintenance free for years (so far).

    I love the kitchen stove vent idea. I love stuff like this more when I make it of discarded parts.
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