I have a 4" infinity inline fan and carbon filter, both are rated at 210 cfm. Lately I have been having humidity issues.
During lights on I set temps at 80 degrees and night time 65 degrees. Here is my problem…day time my fan doesnt run much to keep temps below 80 as my grow room is in a cold cellar so humidity climbs in the mid 60’s.
Night time as the temps drop obviously my humidity goes up. So I added a dehumidifier which takes care of the humidity but then I cant get my room temps below 75 degrees because of the heat from the dehumidifier.
I just ordered a cheap 100cfm 4" inline fan but I’m not sure if I should put that on the intake or add it inline to the exhaust line.
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This is now what I’m working with…
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Why not just run the fan 24/7?
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I’m using an led which performs best with slighty warmer temps. I guess I could run the fan at full speed during dark hours and maybe half speed with light on.
If i added the new small 100cfm on exhaust with 205cfm would that total 300cfm or would the 100cfm just do nothing? Plus the carbon filter is rated for 205cfm so what happens if I try to pull 305 cfm through it?
If you run another dehumidifier in the rest of the basement and set it to keep the humidity at 50%, the dehumidifier in your grow room wouldn’t need to work as hard. Meaning, it wouldn’t need to run as often, which means the temps wouldn’t increase as much in your grow room.
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@Purple-N-Hairy this is kind of what i been doing, running the dehumidifier in the whole basement … My intake sucks fresh air from upstairs but I’ve found my humidity was still higher than i was happy with, turned the dehumidifier on and it leveled things out pretty good.
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Yup - I wasn’t guessing, @rob0781 
I practice what I preach 
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I believed you i was just chiming in because it’s a great idea and i also found out from trying it that it works… @anon81143130 I would try this before buying another fan.
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Yikes - I didn’t mean to sound like I was defending my statement, @rob0781 
and it never occurred to me that you had any doubt about my knowledge. I’m glad you reinforced my suggestion, because, really - it is the easiest solution.
@anon81143130, I know good dehumidifiers aren’t cheap, but if you check out your local craigslist, you might find a good one for a great price. I got my 3rd dehumidifier from craigslist this winter because I needed to get one that worked in low temps. I paid about 25% of retail, and since it was about 10 miles away, shipping was free!
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I already have a good dehumidifier my problem is my intake is from the outside not my basement. In order to run an intake from my basement I would have to go though a think stone wall or the door leading into my grow room.
I’m just not sure how I would light proof an intake though my door without making it look suspicious. Thoughts? I thought about adding a basement intake when building my room just to have another option when summer temps get high.
Can you post a pic of the door area?
BTW - with your intake coming from the outside, you could be pulling in 90+ degree air and/or very humid air in the summer. How long have you been doing doing this?
It’s a crappy old door that doesnt raise any suspicion as its tucked a way in the basement. I used to be an old cold cellar. I built the wall as the room was much larger than I wanted.
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And dont ask why there is a pink board covering the door because I have no clue. Was like that when we bought the house and the door was nailed shut. It was just an old crappy cobweb filled cold cellar.
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@Purple-N-Hairy i really didn’t think you were but just incase i wanted to make sure you for sure knew I wasn’t doubting your knowledge. I love forums and especially this one but just the same as emails and texting sometimes it’s hard to read how it’s meant when written haha anyway i am really stoned and rambling on took me 10 minutes to type “this” far and i still gotta offer a suggestion to @anon81143130 you say your only source of intake is outdoors i wonder if you could build a sealed box for the dehumidifier and suck air from outside and dehumidify it and push it back into the grow?
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Just saw your pics, why not make a intake right into the door? Could even build brackets and mount a inline fan on the door to pull air in and you could have the dehumidifier sitting right outside that door.
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@rob0781 that would definitely work just need to figure out how to light proof.
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That’s a great little room!
Ok, so you’re actually in good shape for making a somewhat stealthy passive air intake.
Take that white board and offset it by about 1/2 inch. If it’s screwed onto that door, just put 1/2 inch spacers between the wood board and the door. Now you have a huge area for passive intake, but you really don’t need all that space. So screw another board onto the inside of the door and cut a 7x7 hole in it. Take this carbon/charcoal filter sheet, which is 16 x 48, and cut it into (6) 8x8 pieces.
https://www.walmart.com/ip/1-X-14ALL-Holmes-Cut-to-Fit-Replacement-Carbon-Pre-Filter/231254374
Now stack those pieces, grab a staple gun and staple them over the 7x7 hole. No light will escape, but air will be able to come in.
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@Purple-N-Hairy it took me a few min to figure out what you were saying but now I get it. That would definitely work without drawing attention to the door.
Think I took 1 too many hits of skywalker lol
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Just an example. Its the side door of my garage. Years ago I had a big doggie door installed. Leveraged that hole.
Old pic. Since added a 6k wall shaker AC. 4x8x8 space.
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(PITA)
