I had an old microwave that had kitchen vent hood and i took it out and put in new kitchen hood range. All went well untill i found out that air seems to be coming in from outside even when the fan is not on. I went on roof and looked at vent roof cap and there is nothing to keep the wind from blowing down the duct work. how do I fix?
2007-03-07 10:56:00 · 4 answers · asked by Rob H 1 in Home & Garden ➔ Do It Yourself (DIY)
There is no flap behind the exhaust fan.
http://www.nutone.com/product-detail.asp?ProductID=975
2007-03-07 11:13:23 · update #1
Look on page 2 at Figure 3 in the installation section of the link you provided. It shows the location of a 7" damper inline on the vertical connection. You will need to get a 7" damper from a home store or sheet metal shop and install it inside the duct (about $8). Most use a weighted rod mechanism that can be adjusted so that the damper will open with the slightest upflow when the fan is turned on and flop closed when it goes off. This is very important for proper operation but in high wind situations they can be sucked open. It's unavoidable but no heavy down drafts should occur. Based on their design, they do not seal 100% - they would jam in the duct - but will reduce air flow considerably.
Good Luck!
2007-03-07 12:16:26 · answer #1 · answered by Pat C 3 · 2⤊ 0⤋
There should be a flap valve after the fan blades in the duct or at the mouth of the duct.
2007-03-07 11:01:42 · answer #2 · answered by J.C. 2 · 0⤊ 0⤋
they usually come with a clam shell flapper that clses flat when fan runs... or go on the roof, make a turn in your pipe to a rt angle & install a deflecto vent cover/dryer vent cover
2007-03-07 11:53:18 · answer #3 · answered by Bonno 6 · 0⤊ 1⤋
Pat c. knows of which he speaks. follow his advice.
2007-03-07 16:47:13 · answer #4 · answered by luther 4 · 0⤊ 0⤋