Cut Tent to Utilize Existing Split Unit A/C

Former outdoor grower here. Lost entire 2023 crop to bud rot due to unusual late season rain and humidity (two 9' Tripicana Cookies and two 8' HSC The Bling, wasted). Im done! Going indoors now with a 4x8 Gorilla and two HLG 750 Scorpions.

I have a perfect place in the garage to fit a 4x8 tent, but it can get to 115F in the summer, and low 40F in the winter. There is a split unit A/C and heating unit already there, where the tent would go.

My question is...Can I cut a hole in the 4x8 tent where the split unit is and use that to control the climate in the tent? My option is to go 4x4 and leave the unit outside the tent.

How’s your head space above the tent?
Space to place an inline fan for a powered intake to suck air from the unit into the tent?
I would fear light leaks by cutting the tent open. If it gets/stays dark enough in there for lights out then I probably wouldn’t worry so much.

Edit: Also.. where would you be exhausting? Given the potential heat in the summer months..venting outside would be ideal.

HydroKid239 said:

How’s your head space above the tent?
Space to place an inline fan for a powered intake to suck air from the unit into the tent?
I would fear light leaks by cutting the tent open. If it gets/stays dark enough in there for lights out then I probably wouldn’t worry so much.

Edit: Also.. where would you be exhausting? Given the potential heat in the summer months..venting outside would be ideal.

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The ceiling is 96". A Gorilla with a 1' ext to 7' 11" is perfect. I'm going to vent straight up into the attic and out a attic vent. I already put a 8" 650 cfm squirrel fan up there I just need to cut a hole in the ceiling drywall when I can match it to the top tent hole. I have a 450 cfm intake fan for active ventilation from the bottom. I'm going to stick a Hepa on the to keep the critters out.

I can use the split unit to keep the entire garage at a moderate temperature. The active in-line would be blowing the room temperature air in, but that might get expensive. More efficient of the AC is blowing directly inside the tent and not having to heat or cool the entire garage. I guess i could duct it to the intake. Also, I can only go 4x4 if it's outside the tent. I can't easily move the split unit.

bigboerboel said:

The ceiling is 96". A Gorilla with a 1' ext to 7' 11" is perfect. I'm going to vent straight up into the attic and out a attic vent. I already put a 8" 650 cfm squirrel fan up there I just need to cut a hole in the ceiling drywall when I can match it to the top tent hole. I have a 450 cfm intake fan for active ventilation from the bottom. I'm going to stick a Hepa on the to keep the critters out.

I can use the split unit to keep the entire garage at a moderate temperature. The active in-line would be blowing the room temperature air in, but that might get expensive. More efficient of the AC is blowing directly inside the tent and not having to heat or cool the entire garage. I guess i could duct it to the intake. Also, I can only go 4x4 if it's outside the tent. I can't easily move the split unit.

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I have seen it done before, ideally you only have to cut the extension. Depends on the height obviously. I gave up flowering from May until october too much cost and stress.

If you measure it all correct and cut it nearly there's no reason why you could slice a hole in tent that fits the wall unit perfectly and slide the tent hard against the wall over the AC. Then just duct tape to seal it if you want. If you nail it it'll be a pretty kick ass mod.

you could also set up a 4 x 4 next to it and exhaust into the 4x4 and have a perpetual set up

bigboerboel said:

The ceiling is 96". A Gorilla with a 1' ext to 7' 11" is perfect. I'm going to vent straight up into the attic and out a attic vent. I already put a 8" 650 cfm squirrel fan up there I just need to cut a hole in the ceiling drywall when I can match it to the top tent hole. I have a 450 cfm intake fan for active ventilation from the bottom. I'm going to stick a Hepa on the to keep the critters out.

I can use the split unit to keep the entire garage at a moderate temperature. The active in-line would be blowing the room temperature air in, but that might get expensive. More efficient of the AC is blowing directly inside the tent and not having to heat or cool the entire garage. I guess i could duct it to the intake. Also, I can only go 4x4 if it's outside the tent. I can't easily move the split unit.

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If you go directly into the tent with the split you could have a sealed unit and set up CO2

No space. It

ilovetoskiatalta said:

you could also set up a 4 x 4 next to it and exhaust into the 4x4 and have a perpetual set up

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No space for that. It's fitting in 8' 4" space between two large garage cabinets.

ilovetoskiatalta said:

If you go directly into the tent with the split you could have a sealed unit and set up CO2

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CO2 and a sealed unit is too much hassle. I'm just a hobby grower. I give most of it away. With an 8" 650 CFM extract fan and 450 CFM active intake, I'll have plenty of C02 flowing through the tent.

The A/C is fine where it is. Turn it all the way up and freeze out the garage. Get a good fan/filter combo and suck out all the hot air from inside the tent while using a few passive intakes with 4" or 6" duct sucking all the cold air in. Should keep the tent around 80 degrees with light on if the a/c is good enough.

If it were me I'd use two 400 cfm fans on each side of the tent sucking the hot air out and blowing into two 700 to 800 cfm carbon filters running 24/7. The passive intakes will keep the tent cool by sucking in the cooler air from outside the tent.

Samwiseman420 said:

The A/C is fine where it is. Turn it all the way up and freeze out the garage. Get a good fan/filter combo and suck out all the hot air from inside the tent while using a few passive intakes with 4" or 6" duct sucking all the cold air in. Should keep the tent around 80 degrees with light on if the a/c is good enough.

If it were me I'd use two 400 cfm fans on each side of the tent sucking the hot air out and blowing into two 700 to 800 cfm carbon filters running 24/7. The passive intakes will keep the tent cool by sucking in the cooler air from outside the tent.

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Cooling the entire, semi-insulated, garage enough to keep cold air flowing into that tent 24/7 through the entire grow would cast at least $250 in electricity per month.

bigboerboel said:

Cooling the entire, semi-insulated, garage enough to keep cold air flowing into that tent 24/7 through the entire grow would cast at least $250 in electricity per month.

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you seem to have the set up planned. the tent extension is not that much even if you had to buy it twice

I don't understand why you would want to cut your tent. Can't you just turn the AC on in the summer months and it will cool down your garage and then the tent will draw the cold air in? As long as you are running a carbon filter inside the tent it should draw the cold air into the tent keeping the temps down?

Cut the 4 x 8 to fit the indoor unit and run the intake/exhaust fans on minimum.

Fish scale said:

I don't understand why you would want to cut your tent. Can't you just turn the AC on in the summer months and it will cool down your garage and then the tent will draw the cold air in? As long as you are running a carbon filter inside the tent it should draw the cold air into the tent keeping the temps down?

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He doesn't want to cool the whole garage because it'll cost more than just cooling the tent. It's a big garage with a small space for a tent.

I went out with the tape measure, pen, and pencil. I have the solution!

The 8' garage cabinet to the left is two separate 4' sections. I can easily pull 4' out and just lose some storage. It's just storing old paint cans and drop clothes anyway.

I'll move the tent all the way left and that will leave the mini-split outside the tent to the right. I'll put a short 30" tall by 4' wide cabinet under the mini-split and cut a 20"x24" hole in the top covered by a filtered return air grill. I'll put the 6" 450 CFM in-line inside the cabined and duct it straight into the tent. The mini split will be 24" directly above blowing straight into the hole in the cabinet top. I might even duct it in with 1/4" drywall.

Whatever you decide to do just remember the ac blows out about 20 degree colder air than it sucks in. So if your tents a nice 75 degress with the ac inside the tent, whats being blown directly on the plants is about 50 55 degrees. I don't like air colder than 68 or 70 coming into my tent. Feel like it slows growth during light on hrs

bigboerboel said:

I went out with the tape measure, pen, and pencil. I have the solution!

The 8' garage cabinet to the left is two separate 4' sections. I can easily pull 4' out and just lose some storage. It's just storing old paint cans and drop clothes anyway.

I'll move the tent all the way left and that will leave the mini-split outside the tent to the right. I'll put a short 30" tall by 4' wide cabinet under the mini-split and cut a 20"x24" hole in the top covered by a filtered return air grill. I'll put the 6" 450 CFM in-line inside the cabined and duct it straight into the tent. The mini split will be 24" directly above blowing straight into the hole in the cabinet top. I might even duct it in with 1/4" drywall.

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You might want to look into a lung room or lung cabinet.

I think its going to be a huge waste of energy doing it the way you are planning. You are telling me it's 105 constant outside where you live? Closed room co2 plus dehu/humidifier isn't an option?

In that case look at your house as an envelope.. do not exhaust outside but rather circulate the grow room air into your house to be cooled further and bring seperate intake back from your house going into your tent to make your house the lung room. If your garage gets hot because it's uninsulated then just duct the tent directly to the house, leaving the garage out of the equation. It would also be good to have the grow tent insulated

If it is getting hot inside your garage due to lack other reasons and it doesn't usually get above 90 degrees peak hours you may be able to just use outside air without wasting air conditioning

The way I see it is your air conditioning will just fly outside wasting money

Nizza said:

If it is getting hot inside your garage due to lack other reasons and it doesn't usually get above 90 degrees peak hours you may be able to just use outside air without wasting air conditioning

The way I see it is your air conditioning will just fly outside wasting money

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You make a VERY good point Nizza (why I'm here, to learn). I would be blowing cold air into the tent efficiently, but the cold air will be sucked out the top and into the garage attic instantaneously. That would require the A/C to run full time on 100 degree days to keep a constant temperature in the tent.

This is only a summer issue. In the winter I likely won't need any HVAC at all if I run the lights at night. It might get down to the 50's in the space lights out, but that's ok. With the attic insulated now, an hour of running the split on heat will be plenty to keep it in the mid-60s.

This garage is not the garage attached to my house. It's my Mancave and sits alone about 100 feet away. I just insulated the attic, but I'm not ripping out drywall to insulate the walls.

This is just one hobby of mine. I'm not investing in lung rooms and C02. I give 90% of the finished product away to friends and family. If I get more than 2 lbs out of this tent, everybody I know will be in a constant state of baked.

I would ditch the tent and build a couple insulated walls, then possibly vent into the garage to cool it some as well. I don’t understand peoples obsession with tents. I bought one, tore it down and use it occasionally as a veg space if I need extra room, tents are a waste of money IMO. Just another gimmick everyone thinks they need. Show me a commercial grower with tents lined up.