Back draft damper

Just wondering if exhausting to outdoors should this be included in the venting system in case of power failure during cold months.

Old Cro said:

Just wondering if exhausting to outdoors should this be included in the venting system in case of power failure during cold months.

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Ya I put a back draft damper on mine. Because in the winter some morning the grow room could be down to 10-14*C. Not ideal. So I threw a damper on and didn't have that issue after.

Yep. We get well below freezing and down below 0f here...I'll be adding one of the AC Infinity backdraft dampers to mine.

I put one on my tent to stop the convective flow when the fan is off.

Three Berries said:

I put one on my tent to stop the convective flow when the fan is off.

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Right now I'm not turning my fan off, so not an issue, but I did get backdraft previously and it was blowing the skunk right out of the tent once the outside evening temperatures dropped and that forced air down and through (basement level window). So it would be pretty useful for that kind of thing. Also yes, would work on an intake as well, in reverse.

LeastExpectedGrower said:

Right now I'm not turning my fan off, so not an issue, but I did get backdraft previously and it was blowing the skunk right out of the tent once the outside evening temperatures dropped and that forced air down and through (basement level window). So it would be pretty useful for that kind of thing. Also yes, would work on an intake as well, in reverse.

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My fan is pretty cheesy, when I put in three lights it can't keep up with the damper installed. So I'm getting a bigger fan. But when it goes off as the lights go out it then cools down to room temp quite quickly without the damper.

Going outside you should definitely have one. My flower room exhaust to the attic and has the normal damper in it. Both are 4" pipes.

I'm running a 6" out at ground level under my shop and it has a 6" aluminum dryer vent on the end with one big door for a flap so that stops reverse flow. Must have put that in 12 years ago and it's never stuck open yet, knock wood, but could freeze out my grow room in an hour if it did stick open when it drops to -38C which is the coldest we've had yet but -35 once in awhile is normal. Average is -20 for the whole winter around here.

Waiting for that fan to die and have an 8" with adaptor to replace it with. The exhaust is hooked into a temp/RH and speed controller so only runs at 60W when needed instead of the full 120W. My intake air does not come from outside but from the rest of the basement area that can get down to just a few degrees above freezing late in winter but never got over 68F this unusually hot summer so no A/C needed.

I'd like to run a vent pipe up over my shop roof so the stink doesn't hang around the yard but that would take some screwing around to get from underground thru to the outside. The 20' of upright would get a lot of frozen condensation in it too so fuggit. I vented into the attic of the garage at my place in town 20 years ago and it was raining inside when spring came. Was like a winter wonderland up there.

Three Berries said:

My fan is pretty cheesy, when I put in three lights it can't keep up with the damper installed. So I'm getting a bigger fan. But when it goes off as the lights go out it then cools down to room temp quite quickly without the damper.

Going outside you should definitely have one. My flower room exhaust to the attic and has the normal damper in it. Both are 4" pipes.

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I think all winter would be fine if my fans are running. Even though cold out, the tent is in the utilities room in our basement and our boiler (modern one, 5 zone baseboard radiator heating thoughout the house) and the basement level never falls below 60, and with the door shut to the room it remains in the 70's most of the day. So far at night (without heat running) the lowest I've seen is 67f and once the lights kick on early morning and the boiler kicks in when we wake up and shower we hit the 77-78. But no need to tempt fate, so I'll put in the damper. I also need to make a 'blank' for the window with a 6" cutout so all cold air leaks stop. Right now it's not bad, but only getting into the mid 40f range at night.

I did spring for decent fans. I have a T6 for exhaust and a S6 for intake. Though I'm not leveraging the temp/RH controller since when the fan turns off the backdraft happens. Also, I can't use the intake fan along with the exhaust fan if they're not synching correctly for speeds, since the intake needs to run at about half the rate of the T6.

So the only reason there is convective flow is if the air is coming in colder at the bottom. How about something like this to raise the bottom air intake to the top of the tent level?