Possible to vent grow tent into A/C return ducting?

highasfvck

highasfvck

Well-Known Member
Currently I have a DR150 grow tent with 1000w hps being cooled with a ventilated hood and 538cfm inline fan. I have it setup as carbon filter > cooled hood > inline fan > exhausting out of tent into same room. It's fine as long as I can leave the door open to the room, but as soon as I have to shut it for any reason temps can shoot up to 90F.

I have no way to cut through walls or ceiling for the exhaust because I cannot vent into any of the adjacent rooms safely. I do have two A/C vents in the room though, one to blow cold air into the room and another filtered return vent that has 6" ducting, the same as my grow setup. Can I hook my grow tent exhaust into the A/C return safely? The vent will only "suck" air while the A/C is actually running, but will my inline fan still blow the hot air out of the room through the ducting when the A/C unit is off periodically? Could it cause any harm to the A/C unit or upset it's pressure somehow? Could it cause mold to develop in the A/C ducting for any reason? Humidity in the grow room is relatively low around 32-35%.

Any thoughts help and input is greatly appreciated! Thanks guys.
 
Saldaw

Saldaw

Well-Known Member
i hooked mine up to the AC exhaust. so far no problems but its only been a month. im not sure if it can cause problems.
 
highasfvck

highasfvck

Well-Known Member
Saldaw said:
i hooked mine up to the AC exhaust. so far no problems but its only been a month. im not sure if it can cause problems.
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Good to know! What did you use to connect the ducting? Some kind of a flange? I was just considering duct taping them together, but would like to know if there is a better way.
 
superstoner1

superstoner1

Well-Known Member
key word....... hopefully. hopefully you wont have to find out but i think it is a terribly bad idea to even take the chance.
 
highasfvck

highasfvck

Well-Known Member
Grow4tho187 said:
I don't recommend that
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Can you give me reasons why you wouldn't recommend it?

superstoner1 said:
key word....... hopefully. hopefully you wont have to find out but i think it is a terribly bad idea to even take the chance.
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If smell is the only concern, I will just unhook it if it becomes a problem. I'm more worried about whether or not it would cause any permanent harm to the A/C system or the grow itself.
 
cflgrower1313

cflgrower1313

Member
try it out cant tell till flower time if smell gonna be a problem and you can test when the time comes by simply turning on a/c as far as mold if it a central air system it blows hot and cold so should be fine just take off vent and check every two or three days at first to see if you see water dropplets forming if you dont then your fine
 
Kush Killington

Kush Killington

Well-Known Member
Im doing that right now, except im venting the hot air from my ac in my house ducts. Works well, keeps me warm. And i got no filter on it. Me and my roommates smoke plenty of kush to make the smell irrelevant... For now. Either way ive seen no negatives about it.

Sir Killington.
 
highasfvck

highasfvck

Well-Known Member
superstoner1 said:
your life, if you like living behind bars.
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It's just me in a single family home. Only time someone will smell it is if I have guests over. If my A/C is kicking out a dank smell from my grow, I just won't have anyone over until I fix it. Like I said my main concerns are just that I don't overheat my grow or over-stress my A/C unit since I own the home.

cflgrower1313 said:
try it out cant tell till flower time if smell gonna be a problem and you can test when the time comes by simply turning on a/c as far as mold if it a central air system it blows hot and cold so should be fine just take off vent and check every two or three days at first to see if you see water dropplets forming if you dont then your fine
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It's a central A/C system that also doubles as a heat pump. There is no furnace. Where I am the climate is mostly warm all year round, so it's usually running cold A/C day and night.

Alexander Supertramp said:
The possible odor issue is about it. It will not cause any harm to the ac unit or the grow.
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This is what i needed to know. As long as my grow can adequately exhaust heat without stressing the A/C is what I care about most. Ever since I got my carbon filter I haven't had many odor issues even during flower. I can't see tying into my A/C ducting as creating a new odor issue, but if it does I can simply unhook it before anyone would ever smell anything.

Kush Killington said:
Im doing that right now, except im venting the hot air from my ac in my house ducts. Works well, keeps me warm. And i got no filter on it. Me and my roommates smoke plenty of kush to make the smell irrelevant... For now. Either way ive seen no negatives about it.

Sir Killington.
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So you're venting the heat from a portable A/C unit, not your actual light then. Right?
 
Kush Killington

Kush Killington

Well-Known Member
Yes but same idea. The portable sucks air out of the room and exhausts it smell and all.
I would vent my lights in the same manner, but it gets to hot, plus i can air cool them in a loop so no air exchange.
 
Alexander Supertramp

Alexander Supertramp

Well-Known Member
Its no extra load or stress on the ac. Ducting into the room or directly into the return the ac unit is still dealing with the same work load. Only thing you may want to consider is adding a duct booster somewhere in the return duct. Especially if it is a long return run...
 
highasfvck

highasfvck

Well-Known Member
So I hooked everything up last night and I am pleased to say it was working fantastic! My grow room has never been cooler. The return ducting is not very long, The hallway right outside of the grow room has the thermostat and the main (large) A/C return vent. I popped my head up into the main vent and could see the one from the room was pushing out all the hot air perfectly. Only problem is my A/C return in the grow room is on the ceiling and the exhaust came unhooked and fell down. I tried to just stick it up there with a duct starter that came with and adhesive pad around the flange. I might try to stick it back up and use some extra duct tape this time. Does anyone have any good ideas of how to keep this thing up in the ceiling vent? There doesn't appear to be anyway to screw it in because underneath the vent cover it's just a foam box surrounding the return ducting. It would seem the only way some type of adhesive.
 
highasfvck

highasfvck

Well-Known Member
Alexander Supertramp said:
Go to Home Depot or the like and search the HVAC section and I bet you find the sort of adapter you need. Usually what ever adapter is in the ducting holding the vent grill will work fine by just removing the grill and then screw
them together face to face...hope you understand what I mean.....

EDIT: I am guessing you are dealing with an adapter similar to this

https://www.ductworks.net/store/products/wall-stack-register-straight-boot/
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No its like this ending into a foam box. https://www.ductworks.net/store/products/flex-duct-start-collars/
 
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