Exhaus fan/thermostat wiring question

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  #1  
Old 07-16-12, 07:49 PM
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Exhaus fan/thermostat wiring question

I'm looking at putting some sort of fan in my media closet to vent heat into the attic. I'd like to have a thermostat to only run it when necessary.

I've been considering something like this, but I'm not sure how I'd wire the two up together.

6-In 110VAC 250CFM In-Line Duct Fan - DB200 - Smarthome

DuctStat Automatic Duct FanThermostat - DS100 - Smarthome

I'm inferring from the website that they can work together. Is it possible to put a gang box on the side of the fan, and then wire it into a plug that I can use to plug into the thermostat? Is there a safe way to do it?
 
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Old 07-16-12, 09:46 PM
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Any exhaust fan, including a standard bathroom exhaust fan, and any thermostat will work. One advantage of installing a standard bathroom exhaust fan is that they come with flaps that close the exhaust duct when the fan is not running, to prevent air and heat loss. One advantage of using an ordinary thermostat is that very few of them cost $32.
 
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Old 07-17-12, 07:41 AM
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It looks like you could cobble that together and make it work. I would however NOT vent that directly in the attic. Venting warm air into the attic during the cooler months can cause condensation which will promote mold growth up there.

You might consider a wall mounted thermostat and use a 24vac relay to control the fan. It would be a cleaner install.
 
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Old 07-17-12, 07:43 AM
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Nope, don't vent into the attic.
 
  #5  
Old 07-17-12, 11:29 AM
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Instead of venting into the attic directly, is it alright if I tie into an existing bathroom exhaust duct?
 
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Old 07-17-12, 11:48 AM
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One exhaust vent per duct is the usual rule. Why not just use a through the wall vent to the next room? Example: Condar Between Room Vent
 
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Old 07-17-12, 12:01 PM
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Well, my original plan was to have a vent in the bottom of the door, and a vent above the door. The problem I was trying to solve was how to actively move the hot air out with out it being loud. It's gets pretty warm in there with the door shut, and that's not that great for the electronics.
 
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Old 07-17-12, 12:07 PM
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Tieing in to a bathroom vent duct is not ideal, but it is better than the attic. You would need to put some kind of check valve on the media closet to keep the humidity and odors from the bathroom from entering the media clost when the bath fan is on. Realize also that heat from the media closet will go into the batroom as well as outside if a second check valve is not placed in that line.
 
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Old 07-17-12, 01:23 PM
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Avoid having two fans pushing air into one (undersized) exhaust duct. With multiple intakes, you are better off pulling air.

If you cannot add a roof or wall penetration for this fan for some reason, the next easiest solution is a single inline centrifugal fan. That would of course require space in the attic or elsewhere, but it would allow you to draw air from both the bathroom and the closet.

I am drawing air from two rooms with one roof-mount fan, the Fantech RE-6. The ducting is 6" through the roof and a wye splits that into two four-inch ducts with spring-loaded backdraft dampers on each intake.

With undersized ducts, you may have to do some tuning and speed adjustment (using a fan speed control switch) to avoid whistling. This will usually reduce your actual CFM.
 
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Old 07-17-12, 01:36 PM
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I was trying to solve was how to actively move the hot air out with out it being loud.
The fan I linked to has sound deadening and is designed for the purpose you need a fan for. Condar Between Room Vent No, I haven't used that fan and can't verify it lives up to it's hype but I believe it is the type best for your use.
 
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Old 07-17-12, 03:08 PM
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Tieing in to a bathroom vent duct is not ideal, but it is better than the attic. You would need to put some kind of check valve on the media closet to keep the humidity and odors from the bathroom from entering the media clost when the bath fan is on. Realize also that heat from the media closet will go into the batroom as well as outside if a second check valve is not placed in that line.
Bathroom fans almost always come with a built-in check valve (flap) in the exhaust port. Just make sure both your old and new one do. Use a manufactured "Y" to do the tie-in.
 
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Old 07-17-12, 05:23 PM
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I suggest installing a line voltage thermostat inside the cabinet that close on temperature rise. IE: line voltage cooling thermostat
 
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