Cold Air Coming In!

[migreen]

Howdy all, my grow box is vented outdoors for odor control and temp control...My exhaust fan is 170 cfm's...It shuts off by timer with the light...now after fan is off the cold air from outside falls naturally down the pipe into the grow box and the plants are getting colder than the basement...I can leave on the fan 24 hrs...put in a manual damper (then I would have to be their every nite to turn it...or I could pay 90.00 for an electric damper and hook it up to the timer ( would rather NOT spend more money ).....any other ideas? Lets hear them..

Thanx, migreen

[Beans]

You need a spring loaded back draft damper like this

http://www.rewci.com/416splobada.html

[migreen]

You need a spring loaded back draft damper like this

http://www.rewci.com/416splobada.html

 

 

Yep, considered this, not sure if my fan will open it or how far...i have been reading and trying to find out how many cfm's these back draft dampers need to open all the way....thank you for the your responce. migreen

[MrShpongle]

I have 4 backdraft dampers, and I can tell you that with only 170 cfms they won't open 100%, but you don't need them to open that far to be effective. I went through the whole electric vs. spring-loaded damper debate 9 months ago, and I'm glad that I didn't get the powered one - just another part that will eventually fail. Green Thumb in Ferndale usually has them in stock for under $30.

[Dlo]

You can buy a damper at Homedepot for around $10.00

[DenturesLost]

Use a dryer vent cover. They have a damper on them that opens more easily than a spring-loaded damper and closes with gravity after the forced air shuts down.

[coreyz]

If your sucking in cold air form outside how do you stop the condensation from building up and dripping?

[Mememe]

double layer of garbage bag is heavy enough to close when there is no airflow but light enough to open when there is.