AC window unit & fresh air

Building grow room in my shop, size 6ft X 7Ft X 7ft. Will have an AC window unit and a stand alone heater. Hot summers and cool winters. Question is will the AC bring in some fresh air that is needed to keep plants happy. I keep reading about separate air ducts and filters. I want to get this right while I’m in the framing mode, the four walls are built just not together yet. Thanks in advance.

I don’t believe the ac unit will bring in any new air but rather condense the air that’s already in the shop. Of course it’s sitting half in half out but that half that’s out is the release the hot air that’s the output of the motor running. Is your shop well ventilated? If so should be fine.

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Run a 6 inch freash air intake, shouldn’t need a fan

Some units have an outside air injection that can be opened.
Do you have a model # on that unit?

Also I have never seen a shop that was air tight. Otherwise we would suffocate ourselves in them.
But as stated a vent in and out is needed for your grow space.


Thanks for the replies, the shop is 30ft X 40ft and going to put the room in the corner. So I can just run a 6” vent from the outside of shop to the inside of room and not having to use a inline fan. I didn’t like the idea of an inline fan pulling very hot air from the shop into the room. Thanks again.

Depending on where you are located and temps during summer or winter that may or may not be best.
Without being exact where about are you? Nearby big city? Even just what state?

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We are in the Deep South of USA, mid to upper 90’s the normal for summer which runs a long time, winters are cool, we get some frost.

Most of the time you need to supplement co2 when running ac in sealed room. You’re pretty much stuck either exhausting your conditioned air or adding co2.

The good news is that if you install traditional intake and exhaust you can probably run that way for a good portion of the year. Just make them so you can bypass.


Thanks, I’m getting a tad confused. I can understand putting say a 6” hole in one of the walls for some ambient air into the room, but I wouldn’t want an exhaust fan to take my nice cool or warm air and sending outdoors. My head is swirling and not from no smoke- lol. Thank you.


In the summer you would want to exhaust that used air back into your shop for a bit of additional a/c there. Input air would likely need to be forced (inline fan) air but could put on timer to reduce heat load on grow space. (Run for 5 minutes every hour for example)

If I was in the Deep South I think I would plan all my Grows in the winter months I just think it would be easier to control the perfect climate. Just a thought happy growing.

Conserves your heat or cold …not really a bad price either.

No the AC won’t bring in fresh air. It sucks the air in the room and then blows hot air out the back.

Since I can’t put my AC unit in the window so I put a fan behind it and it will blow the hot air out of the room. This works like a champ.

@kellydans I’m also in the Deep South where it’s not unusual to have temps hitting past 115 degrees and this is before the humidity factor down here.

It’s not as easy as you would think. We can still hit high 90’s in November. But we have also had snow in the same month.

But you are correct that the best time to grow in the South is the winter months. Problem is we may not have winter temps till late Dec and Jan. So it’s a Russian roulette game with the weather here.

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The hole being there won’t necessarily replenish co2 plants are using. That’s really the issue.

Thanks for the reply, I really have to rethink this issue of needing some fresh air, I understand the need for it, just have to figure a way to make it happen. I appreciate everyone’s input.

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