Damper for Passive Intake

[MissyGreen]

Hello Fellow Farmers,

This is my first post and wanted to start off by saying a big thank you to the community for all the info presented here (I've been lurking for quite awhile).

I'm planning on building an outdoor shed-style building. The flowering room will be 1300 cubic feet and I'm planning to exhaust it with a 12 inch 1200 CFM in-line fan. Starting off for now with 2 1k Adjust-A-Wings (could eventually grow to 6 in the future) and no supplemental CO2.

With the general guideline of having your passive intake twice as large as your active outtake, I'm planning on an 18 inch passive intake. Now my question: can I use a 18 inch butterfly backdraft damper on this? Will there be enough negative pressure in the room to open this? We're starting to get some cold weather now and I don't want that seeping in when I don't want, especially when the girls are sleeping. It would be nice not to have pay an extra $100 for a motorized damper.

I thankfully appreciate your responses.

 

[MissyGreen]

Anyone out there use a damper on a passive intake?

 

[eyeslow999]

18 inch in? for 2 lights? sounds like serious overkill. an 8 inch max fan will handle that, probably dont need an intake it will suck air throigh the shed

 

[Rushed]

I had 3 - 4" plastic inline flappers that closes by weight and opens with pressure, installed near the floor in an outside wall, spread out. And a 6" inline fan on a six carbon filter in the middle of ceiling exhausting out.
I regulated my fan plugged into this controller.http://www.amazon.com/Lux-Heating-C...NYY8/ref=sr_1_1?ie=UTF8&qid=1326491285&sr=8-1
Worked great in my 1344 cu' area and could keep my temps steady right where I wanted them.
Good Luck

 

[hiboy]

I dont think ull move them wings,,,u can weaken the springs in them by tweaking them a bit, but if ur passive intake has no fan motor it wont move them. Motorized would be the way to go
h

 

[MissyGreen]

I had 3 - 4" plastic inline flappers that closes by weight and opens with pressure, installed near the floor in an outside wall, spread out. And a 6" inline fan on a six carbon filter in the middle of ceiling exhausting out.
I regulated my fan plugged into this controller.http://www.amazon.com/Lux-Heating-C...NYY8/ref=sr_1_1?ie=UTF8&qid=1326491285&sr=8-1
Worked great in my 1344 cu' area and could keep my temps steady right where I wanted them.
Good Luck

Interesting Rushed....How many lights do you have and their wattage? What's your 6" fan's CFM? What are your summertime outdoor night/day temps?

 

[MissyGreen]

I dont think ull move them wings,,,u can weaken the springs in them by tweaking them a bit, but if ur passive intake has no fan motor it wont move them. Motorized would be the way to go
h

Thanks for the input hiboy.