Safe to put exhaust fan in attic?

If i was growing in a closet, and planning on venting into the attic and then out a roof vent, would it be ok to put the exhaust fan in the attice above the closet? to where it was sucking air out of the closet via duct and then out the thru the roof? During the summer it gets to 100f here and in the winter can get down in the teens. I'd just wnat to make sure the fan wouldnt overheat up there during the summer.

No. Hot, humid air in the attic = mold. If you would like to vent through your attic then install a roof vent like this: http://www.homedepot.com/p/Speedi-Products-6-in-Black-Galvanized-Flush-Roof-Cap-with-Removable-Screen-Backdraft-Damper-6-in-Collar-EX-RCGC-06/202907395

Also, ensure you use 6" INSULATED duct or the hot, humid air in the duct will start dripping condensate water back down onto your electric fan.

These are commonly used to install bathroom vents CORRECTLY. Everything else may cause mold buildup, including soffit vents.

Edit to add: IF you have a really old house with loose construction and super high heating bills in the winter and no insulation at all in your attic then you're probably fine to vent straight into your attic as the construction is probably so loose you wont have any issues.

I will be venting out the roof thru a roof vent. What i was asking was if it was safe to put the actual exhaust fan in the attic. Would it get too hot up thee in the 100 degree summer months? Would the motor burn up , etc?

To do this correctly you should..

Mount the fan on the inside of a rafter between the joists (if it fits, if not mount it on top of the joist) Then build a box out of 2" XPS insulation and the silver HVAC tape to fit over the fan (much simpler if it fits between the joists) so that the bottom of the box is flush with the drywall and cut a hole in the top of the box just large enough for the 6" duct to fit through but not the insulation around the duct.
Bring the duct through the top hole and connect it to the fan, now set the box down over top of the fan and flush with your drywall ceiling (you may have to move some insulation). Now use Loctite PL300 around the bottom of the box and the dry wall to make an airtight seal. Do this around the ducting coming out of the top of the box too and then just slide the duct insulation down so it's flush with the top of the duct.

If your motor ever burns out and you need to replace just use a utility knife to cut through your beads of caulk.

The short answer is yes, temps in the attic should be well within the operating range of your fan.

both of those answer are right

it all depends on the roof design .........alot of homes /detached housing have air slits in the side to allow a cross breeze to remove heat ...some houses have a whole fan system to do this .......then others are completely sealed off like town houses

if u are a sealed on then the first guy is 100% correct u will cause all that to kick up and enter in the house .........u will have 3 choice 1 to do what u planned too but run a strait piece of ducting (actual ridged ducting from the roof to the ceiling of the closet make sure to insulate it )
2 run the ducting drier vent
3 run it to chimme

catfishclyde said:

If i was growing in a closet, and planning on venting into the attic and then out a roof vent, would it be ok to put the exhaust fan in the attice above the closet? to where it was sucking air out of the closet via duct and then out the thru the roof? During the summer it gets to 100f here and in the winter can get down in the teens. I'd just wnat to make sure the fan wouldnt overheat up there during the summer.

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Nah, the fan will be fine in those temps. Personally, though.. I would just mount the fan on the ceiling inside the grow space and just pump the air into the attic. Just make sure to add a carbon filter a few weeks into flowering. Putting your fan in the attic may (depending on the fan) be easily heard from outside.

exhausting into the attic will cause mold.

My fan is in the attic in my garage. The fan is mounted on the floor sucking from my room and pushing it 3ft out a vent in the roof. summer temps hit 100f and winter -30f, never had a problem and it's been on constantly for 4 or 5 years!
You'll be just fine.

dux said:

My fan is in the attic in my garage. The fan is mounted on the floor sucking from my room and pushing it 3ft out a vent in the roof. summer temps hit 100f and winter -30f, never had a problem and it's been on constantly for 4 or 5 years!
You'll be just fine.

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thanks. That is exactly the answer i was looking for. Mine will be blowing the air out a vent in the roof about 20ft away though... Its a 6" ventech 440cfm with a speed controller.