Intake grill and register for in-line exhaust fan

Old 11-16-15, 12:39 PM
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Intake grill and register for in-line exhaust fan

I will soon be installing an in-line exhaust fan for a large bathroom (Panasonic Whisperline). I'm just trying to get all the various parts in hand and can't decide what to use for the intake grill and register boot. If I look at ones specifically for exhaust fans, they are unusually expensive (often $100). But can I use just a regular grill and register vent boot, such as ones that someone would use for an HVAC outlet? Or does it have to be a specific kind? I've installed a ceiling mounted exhaust fan before but never an in-line, so piecing this together has proven to be tedious.

Also, do I really have to get a backdraft damper as opposed to an exterior wall outlet that has a spring return damper?

Last edited by alisonmadrey; 11-16-15 at 12:49 PM. Reason: addition
Old 11-20-15, 11:40 AM
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Fantech also makes a lot of in-line fans, as well as dampers, grilles, etc. that might work with your fan. I suggest you check their website or large home improvement stores for their products.
(NOT an endorsement for Fantech; I just know they may have what you need.)
Old 11-20-15, 01:55 PM
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I think the reason they recommend a backdraft damper is to prevent cold air (in the winter) from drifting down into the room when the fan isn't being used. The air in the duct will eventually cool off, even if it's insulated, and because cold air sinks, it will ooze into the room and be replaced by warm air, which will then cool off and fall into the get the idea.

I don't see why you couldn't use a conventional register and boot, except for it not having a backdraft damper. You would want to seal it well where it penetrates the ceiling and insulate it.

You still want a spring damper on the outlet to keep the critters out.

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