Venting into a cold attic? Advice Appreciated

So here is the deal. I have some heat issues in my cabinet at the moment and am being forced to change my exhaust. You will see by the pictures that my cabinet has 2 chambers. What am planning on doing is changing the exhaust from the back of the cabinet to the top. The upper chamber will flow straight up through the top of the Cab and the lower chamber will do the same however the ducting will run through the upper chamber and again out the top. I currently have one small 80 cfm fan for intake and the exact same for exhaust (hence the fricken heat issue) !! I plan on changing the intake to passive (out the side of the cabinet) and putting both small fans to exhaust. I plan on running a 6" duct out of both chambers, up through the ceiling into the attic. At the end of the ducting (in the attic) I will mount a 6" boster fan to each one.
Finally to my question....... If I am sending warm air into the attic in the winter (where I live it is DAMN cold, like -30C) will I have a condensation issue in the duct work? Will I have moisture running down the hoses back into the cabinet? Will I have ice form on the fans in the attic?
Anyone ever have this question? Even more important, does anyone have the answer?
Thanks in advance for any input/suggestions.

I posted something in the other thread where you ask the same question... It's usually not considered good form to copy a post to multiple forums, pick the correct one and go with just that one

Thanks for the info AND the etiquette tip Gobbly. Was not getting any response, that was the motivation. I will remove this one.

Bad Idea you will get black mold, you need to vent outside or inside for heat.

vent to the outside for the smell has to go somewhere.

woodsmaneh! said:

Bad Idea you will get black mold, you need to vent outside or inside for heat.

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Are u joking? i've just cut a hole in the roof of closet so i could vent into the attic, i did this after asking on the forum. my attic is freezing cold and only the floor is insulated, is this still a no go???

U dont have vents in your roof man keep the duct going threw the attic to a roof vent. But then u gotta worries about the heat turning the air noticeable outside in -30

Hi,
Now most attics have to have vents! They usually have two. Attics have to breath. What you need to do and I know two people that do this; add a oscillating fan into the attic so air keeps moving around. Before you pump air into the roof make sure you can SEE you vents of the side of the attics, it will look like a simple vent, much like a cold air return for a furnace system. I know this to be true since I can do house inspections for home buyers. Obv. than I have building experience.
If you are planning to vent in attic and you put the effort in for that. Its just as easy to vent outside a window Try that first.
Good luck.

You should be ok doing that, just go up there once in a while and inspect it. If it seems too hot or humid, then come up with a Plan B. (Add a dehumidifier up there maybe?) =)

Ya know what's crazy, our power bill up, but our heat bill went down almost equally lol. Reuse, reduce, recycle! =)

it depends on where you live. Humid there, then you don't want to vent to the attic. In fact, if you want your house to last a long time, consider venting the attic In dry climates it's no problem, in fact in really dry climates they suggest you run humidifiers to prevent houses from drying out too much. It also depends a lot on the grow size. A single small plant isn't going to produce much, a larger op it wouldn't matter the climate, you'd have too much humidity.

does any1 know if condensation in the duct work will appear and run down back into the grow area? as i need to know the answer to this question too

if the duct isn't lined you may see condensation all along the duct. There will be moisture wherever you're exhausting too you need to go straight out the roof with that or make sure your roof is ventilated well. err attic is ventilated well.

I'd say line/insulate the duct to beat the condensation problem. I wouldn't think venting up to your attic in the winter would be much of a problem. Many people vent their bathrooms into their attics (though it isn't "code" to do it), including me, and I've checked up there for mold many times over the last few years and found no indication of it at all.

In the summer, though, you might have problems, especially if your roof doesn't have adequate venting. Even if it does, you're pumping hot air into a hot attic. This will cause excess moisture build-up, and your roof will "sweat," which could cause your plywood to warp, and shingles to peel off.

I'd vent it up there in the winter, but by summer I'd have a plan to cut hole in the roof and run the duct up and out the top.

just do it. no mold ..your attic is prolly pretty big and has enough air running through it. ive done it for along time..no worries

First post , you will get condensation, i know because i am doing a similar thing as you and i have been getting a lot of water build up in my ducting 8-(..

RumRonnie said:

First post , you will get condensation, i know because i am doing a similar thing as you and i have been getting a lot of water build up in my ducting 8-(..

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insulated duct.

I have a large attic with 3 of those "Whirly Birds" on the roof to extract the air. My house remains very cool in the summer so it appears as though they are doing their job quite well. In some further research, I have found that most people (including construction professionals) suggest a small amount of warm humid air going up there irrelevant of the season would be just fine. As someone said earlier in the thread, go up there and have a look once in a while. As for condensation running back down the vent hose, I was told to ensure that once the hose is up there, lay it down or hang it parallel to the ceiling (of the inside of the house, not the pitch of the roof) and then attach the booster fan. This will dis-allow anything to run back down. Even tipping the fan forward a little will eliminate any condensation from building up in the housing of the fan itself. Bathroom fans vent A LOT of humid air (created by showers, baths etc... and this air when vented into the attic does not seem to create a condensation problem in the winter.
If anyone has any more suggestions, hints, tips or experiences, I am all ears ! I am planning on doing this in the next 2 or 3 days so I will be sure to report back with my findings !
Thanks everyone for the input. What a great resource we have here with RIU.
Peace