Backdraft dampers

I'm setting up a grow room with CO2 and trying to figure out how to keep the CO2 in the room between ventilation periods (see journal for grow room details: https://www.rollitup.org/grow-journals/232930-first-grow-3000w-ebb-gro.html#post2972131 ).

I'm thinking of using backdraft dampers but I'm not sure whether to use standard or motorized?

http://www.plantlightinghydroponics.com/canfan-inch-backdraft-damper-p-2439.html
http://www.plantlightinghydroponics.com/suncourt-6in-motorized-damper-normally-closed-p-1962.html

Do I put dampers on intake and exhaust or just intake? The intake is at the bottom of the room and the exhaust is at the top. I figure CO2 is heavier than air and since the exhaust is at the top of the room maybe I don't need it on the exhaust?

With the motorized dampers I assume I would get one that is normally closed so that I can connect it to the same power source as the fans so when the fans come on it opens, right?

The motorized damper specs say: 0.25 AMPS, 24 VAC, 60 HZ, and 7 WATTS. Can i connect that to 120V outlet?

I imagine that one of the drawbacks of motorized is that if the motor fails it could really screw up my grow, right?

Would a standard backdraft damper (non-motorized) work with a passive intake? The 1000 CFM exhaust fan will create negative pressure in the room but would it be enough to open the damper? The room is 10x10x8'

Yes I think that the 1000 CFM fan will open the damper

The difference in price between the motorized vs non motorized damper is only $30. I say buy the motorized damper. You'll have much more control over your grow room. Make sure to buy the damper who's default setting with power off is open though. If something were to go wrong with the motor for whatever reason later on, the last thing you want is the grow room starved for fresh air.

But yes, if you did have to opt for the spring loaded damper, that Max Fan is more than capable at opening the damper.

That is the reason why you should just get a regular damper... Why pay 30 extra dollars to have to worry about when the motor is gonna shit out?

KnowledgeSeeker said:

Would a standard backdraft damper (non-motorized) work with a passive intake? The 1000 CFM exhaust fan will create negative pressure in the room but would it be enough to open the damper? The room is 10x10x8'

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yeah non-motorized should be fine

I assume you're worried about the smell leaking out the intake, when the fans are off? One option is to have the exhaust always running - that creates a constant negative pressure, so no smells leak out.

tom__420 said:

That is the reason why you should just get a regular damper... Why pay 30 extra dollars to have to worry about when the motor is gonna shit out?

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Well, in my case, I use a motorized damper and have 2 sources of fresh air. One, is an AC vent from cooler air from within the house (on hot days), and the other is a window with the motorized damper. On hot days, I'm able to pull in cool air from the AC vent, and set the damper on a timer or thermostat to open when the outside temps reach what I'm looking for.

Mcgician said:

Make sure to buy the damper who's default setting with power off is open though. If something were to go wrong with the motor for whatever reason later on, the last thing you want is the grow room starved for fresh air.

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If i did go with a motorized damper i was going to go with the normally closed because i want to supply power (to open) when power is supplied to the fans. How would i do the reverse? With a relay or something?

Green Cross said:

yeah non-motorized should be fine

I assume you're worried about the smell leaking out the intake, when the fans are off? One option is to have the exhaust always running - that creates a constant negative pressure, so no smells leak out.

Click to expand...

I don't want to run constant exhaust because I'm going to be supplementing with CO2. (Why do i choose to make shit so complicated?) I lean towards the non-motorized because that's one less thing that can fail. Thanks for the input.

If you are going to mount the damper in a horizontal position, then be sure to get a spring loaded or motorized damper. A regular damper will not work