Venting into a COLD attic. Advice Please

[wannaweed]

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.

 

[PrairiePoet]

Depends on how well the house is built. You should be able to push warm wet air into a cold attic. It should be ventilated to handle some.

Should be any or much of all of condensation in the duct work or fans.

Looked at your gallery, and your box doesn't look that big. So I doubt you are going to affect the attic much.

Prairie

 

[oldgardener]

Hi,
I would not suggest venting into the atic...remember that most of every gallon of water that you put in the pot is going to be trans-evaporated into the air by the plant.
And those gallons of water would be going into your attic to condense and return to you through the ceiling as a cold wet mess....

Something like a duct roof vent would be best in a warmer climate... something like this:
Roof Vent Kit, 4 In Round - Flexible Ducts - Heating Equipment - HVACR : Grainger Industrial Supply
With a bird screen and backdraft damper.

It sounds to me like you have identified a missing link in the Hydro Supply and DIY market.

Vent duct condensation eliminators for the -30c folks!

Or maybe I just missed them .....
good luck and stay dry
oldgardener

 

[PrairiePoet]

Hi,
I would not suggest venting into the atic...remember that most of every gallon of water that you put in the pot is going to be trans-evaporated into the air by the plant.
And those gallons of water would be going into your attic to condense and return to you through the ceiling as a cold wet mess....

I disagree, IMHO.

His closets are not that big, he won't be putting a lot of water into the attic. At most a couple of gallons a day. Also most attics are designed to vent air out. If wannaweed had a large grow room, then it could be a problem.

Prairie

 

[oldgardener]

Prarie,
You may very well be correct, especially as his closet is not that large.
I have never tried it under those conditions so I am not 100% sure of the possible results.

I was thinking about a television home remodel program I saw "Holmes on Homes". In that program the attic was full of frozen moisture which dripped to the ceiling and sogged out the sheetrock, insulation etc.
In that case, there was something wrong with the ventilation or vapor barrier that allowed the moisture to condense and collect.
As you say, much of this "depends on how well the house is built."
Hopefully wannaweeds is well built and he has no problems.
peace,
old gardener

 

[Llama]

Humidity is the biggest enemy of your attic insulation. You will be amazed at how much your plants give off. I also looked at your grow box. Remember, you are going to have evaporation from watering and your plants will also give off humidity. If you vent directly into the attic you are opening yourself up to mildew and even wood rot if you do it over a period of time. Your best bet would be to run your vent into the attic along a rafter and vent out to one of the the soffit vents. A long piece of dryer hose will work just fine.