Looking for heat conserving exhaust fan

[Bob Slater]

I want to have the ability to purge the air of toxins in the shop and would like to put an exhaust fan through the wall. I don't want my heat escaping when it is not being used though. Anyone know of some type of fan that is sealed when not running?

[John Holder]

You can purchase fans that come with gravity operated louvers from an industrial supply like Grainger or McMastercar

[John Lanciani]

Hi Bob,

I just actually bought one today, it's a broan model #506 - 470 cfm, fairly quiet, has a nicely gasketed flapper door and it was under $100 at the electric supply house.

John

[Gene Michael]

Had an exhaust fan with a louvered grill at the last house. It leaked air like a sieve when the fan was off. Strong winds caused the louvers to flap, letting in more outside air. So, built an insulated box over the fan. It worked well except it was a pain to take off and put back on. My next shop will have a similar fan cover, but mounted on hinges.

[Bob Slater]

Had an exhaust fan with a louvered grill at the last house. It leaked air like a sieve when the fan was off. Strong winds caused the louvers to flap, letting in more outside air. So, built an insulated box over the fan. It worked well except it was a pain to take off and put back on. My next shop will have a similar fan cover, but mounted on hinges.

In a shop I rented years ago, I coated a round plastic wash tub with spray foam, fastened it over the fan, then cut a hinged door in the bottom. Hard to believe I would have to make my own again,, now that energy conservation is such an obvious pocketbook issue. Thanks for the tips.

[Matt Ocel]

You may be able to use an HRV (heat recovery ventilator) or an ERV (energy recovery ventilator). Venmar makes them.

[Matt Meiser]

I have a large fan in in home-built spray booth. Outside it has the louvers and they do occasionally flap in the wind. They are just thin aluminum and don't do much to keep out the cold. Inside there is a false wall that holds a filter frame. The backside of it is covered with that 1/2" thick foil-faced foam board. I also have a cover for the filters that is backed with the same material.

[harry strasil]

I wired up a large (5 ft) squirrel cage fan in the compressor room of a large grocery store many years ago with a set of positive closing and sealed louvers that required a time delay on the fan motor contactor to allow the electrically opened louvers to open 75% before the fan motor kicked on, otherwise it would blow the small room door out of its frame.