Grow room design...

Punisher84

Just some asshole
I’ve started framing my room addition. I need help figuring out what to do. Climate is where I am coming up short. Sealed or vented? I struggle with humidity now.

Guess I’ll explain my ideas and we can go from there. 12’x16’ room, on back of my garage. 8’ ceiling one side and 10’ or so on the other. Garage has heat and air. I already have a mini split for the room, think a 15kbtu. that should maintain temp.

I was going to draw fresh air into the room from the garage, dog door and garage doors don’t seal very well. Draw air down low from garage, up wall cavity into the top of the room add on, I’ll put an air filter on it. Planned on using a 4” fan to exhaust the room 24/7, attach it to a large carbon filter, and exhaust outside. My theory is to keep negative pressure in the room, don’t need to move much air, 50cfm. Would also bring in co2. Negative pressure would also keep odors out of the garage so long as the filter on the exhaust is good.

I struggle with humidity in my tents now. Fortunately the exhaust fans I’m using will exhaust when it gets too high. Humidity in the garage is 45%, so it brings the rh down, but it climbs fairly quick. Set to exhaust at 65% now which I’d like to have lower. Running dehumidifier in garage. Figured on running it in the room as well. My tents just exhaust into the garage now. Should I exhaust them outside? My bigger tent exhausts sometimes for heat, the other I have a heater in the tent that runs even at lights on. Rather exhaust inside then try to kill the smell before it goes outside, filtered twice.

I’d planned on just using tents in the new room, not sure on size yet, prob use the 2 I have for now. Should I figure on getting a dehumidifier for each tent? Not even sure it would fit. In fact I know it wouldn’t. Would I be better served to get larger tents so I have room for a dehumidifier? Having a big flower room I’m not necessarily interested in, rather keep tents so I can have veg right next to flower ect..

I have no intentions to grow a bunch at a time, just want variety and run some testers. Not interested in selling any, just some for the wife and I. Maybe it would be more efficient to get one bigger tent for flower instead of a couple small ones? I struggle to reach the back of my 3x3, I was almost thinking 2x4 tents but what do I know.

Got muddy as fuck framing the floor today, walls and roof hopefully over the weekend. Glad I got the foundation done before winter. Prob go back to work that pays after the roof is on but ill mess around with electrical and such in the evenings.


Any ideas or insight is appreciated.
 

H.A.F.

"Happy Wanderer"
In my opinion...

Don't re-use air. There is no reason you should have 45% rH in the room, but have it that much higher in the tent. Don't re-use air. And I wouldn't fight the humidity either. If you ditch the used air, you should be right in the sweet spot.

Box in an "attic" space. Dump the heat/rH there first on it's way out. You have a big reduction in pressure so the air will not be forced out of the garage at 300cfm.

Did I mention don't re-use air? :)
 

Punisher84

Just some asshole
I have my rooms, total 14.5' x 4' area, venting nonstop into my 22 x 14.5 shop area after going through a big ass filter. Runs about 500 cfm with an 8" max fan. Keeps the grows pretty spot on with what the main room enviro is.
All air intakes have hepa filters on them, and all exhausts have carbon filter scrubbing.
The shop has its own fresh air intake from my garage, and a 6" fan and scrubber venting to the outdoors.
Constant fresh air into the grow, but it gets prewarmed and such by the shop air.
Keeps everything in the mid 70s and 40 to 50 RH.
The 6" fan is the one that controls the overall temps and rh of all of it.
No smells whatsoever.
So you're recycling air if I am understanding this correctly.
You're conditioning your shop air(Heat/cool).

My biggest concern about pulling in air from the garage/outside all the time is in the summer when the fucking humidity is 75% every day and 95% at night. Id have to have a hell of a dehumidifier. Was thinking a smaller air exchange would keep fresh air yet not overwhelm the room with humid air.
 

Punisher84

Just some asshole
Yep, recycling from the shop to the grow, and a separate air exchange system for the shop.
Shop is built into a hill and no heat or cooling to it.
The grow heats it in the winter, and I've got an ac now for summer.
I don't have the high RH issues here though, low is my issue. That's where the recycling helps to hold the RH and temps but still get fresh air from the shop.
I'll be changing it a bit here soon to pull and cycle the air from my house. Pull from the basement bathroom with a 6" on high, and exhaust from the shop into my hvac air return with an 8" on low speed. Will cycle the air through my house from one end to the other and add conditioned air to the shop. My furnace is oversized for the house so the added space is totally fine for the addition to the hvac system.
Until you're in the shop and someone drops a load in the basement bathroom!


Ill set myself up so I have options I guess. Ill have a mini split in there regardless. Ill oversize the intake and probably screw around with the amount of exhaust I am running till I get things right. Might have to change it seasonly..
 

MtRainDog

Blümen Meister
Unless I had a greenhouse, I think I'd always go with tents. You only need to create negative pressure in the tents. The room around the tent acts a buffer. In my situation, I draw air into the tents via ducting from the house, letting my exhaust fans do all the work. Since we have central air/heat, the air pulled into the tents is quite a reasonable temperature. The room around the tent is sealed off, covered in those reflective insulation sheets you can buy at Home Depot/Lowes. This helps trap the heat/cool air in this buffer zone around the tent. Mind you, I'm growing in an attic and am faced with extremes in temperature/humidity all year long.
 

Punisher84

Just some asshole
Unless I had a greenhouse, I think I'd always go with tents. You only need to create negative pressure in the tents. The room around the tent acts a buffer. In my situation, I draw air into the tents via ducting from the house, letting my exhaust fans do all the work. Since we have central air/heat, the air pulled into the tents is quite a reasonable temperature. The room around the tent is sealed off, covered in those reflective insulation sheets you can buy at Home Depot/Lowes. This helps trap the heat/cool air in this buffer zone around the tent. Mind you, I'm growing in an attic and am faced with extremes in temperature/humidity all year long.
I’m sticking to tents for sure. Hopefully be a slick setup once I’m done.

Im sure I’ll screw a bunch of shit up, but that’s how we learn
 
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