How do you provide fresh air for plants in an air conditioned room?

[jburns]

with a window ac, it is pumping in air from outside.

the side vents are intaking ambient external air..... conditioning it and it is coming into your room fresh. heat created is exhausted at the rear.

 

[hush]

^ Not according to all the literature I've come across about window units. I have yet to find evidence of any window unit that exchanges air with the outside, except for that little plastic lever that some models have, that basically just opens a little port between the hot side and the cold side. Here's a basic diagram that shows how window units work, and how the hot side and the cold side are entirely separate (in terms of airflow):

 

[LeeROI]

And that illustration is helpful because it shows how the (potentially stinky) condensate drips outside the building.

The fresh air lever on my (non-grow) LG window unit is so ineffective that I think I'll pull the AC out and put in a window fan.

 

[Benjamin Check]

I think you are going to have to bite the bullet and buy some CO2. Venting in enough 90 degree air to keep ppm levels at 400 will tax an AC unit hard, and waste tons of power. I would certainly spend the extra money if you haven't already and buy a sealed A/C hood, ducting and at least a 400 cfm fan so you can suck out the majority of the heat generated by the 1000w before it even hits the room. If your ambient is 90 degrees, a good 6' inline fan pulling through a sealed duct should be able to keep the temps down enough that the AC wont work too hard. But, you will have to buy a dehumidifier and co2. There's really no way around that with your current setup as you described.

 

[Granger2]

If potentially smelly condensate is a concern, you can put an ONA or cheap version from Lowes by the exhaust, or let it drip into a pan with baking soda. -granger

 

[hush]

So I actually just went out today and bought a 5000 btu unit. The way I see it, since I'm going with CO2 now the temps can afford to be a little warmer. I am removing the window on Monday, so I can mount it with some plywood. At that point I plan on moving the 2x2 tent with the 400w hps into the new room, along with a 250w hps out in the open, just for the extra heat... so I can start testing things.

I'll update after that...

 

[whatthe215]

you don't need to add CO2 if ya don't want to... just have an exhaust and a little intake. you're not wasting AC that way.

think of it this way, if ya let 1000w hang in a tent with no ventilation it will get up to about 125f. now add exhaust and intake from air that is 90f and your temps will drop to around 100f.

add AC and you can be at 78f all day. turn ventilation off and watch the AC not be able to keep up.

you don't need co2. i don't understand why this has gone on for 3 pages... 5kbtu window AC will cool your 1kw in a 90f ambient environment fine.

add co2 as a means to supercharge your growth, not provide "fresh air" because of a lack of ventilation.

 

[vein5]

I tried that with an exhaust and all it did was make my ac run all day never being able to keep up. took out the intake and exhaust, sealed the room and added co2. Now my ac actually cycles on and off. When the ambient temp is 80 degrees its going to be really hard unless you oversize you ac unit. Now that i sealed the room I would never go back.