The rule of thumb is roughly 3,000-4,000 BTU per 1,000w bulb.. So on the low end you'd be looking for a 24,000 BTU unit, but I'd personally get a 30,000+ BTU unit to be safe.

A real ac is measured in tons of cooling power. I would recommend 3 tons. It will keep you covered even on the hot days. Good luck. Peace GS

I have a ventilated 8k, and it still gets in the 90s (basement). I bought a 2 ton split and it can keep the room cool enough, but it has to work pretty hard at it. If I had to do it again, I would go with a three ton.
Chances are you will need and HVAC to vacuum the lines anyway. A cool HVAC can get you a super bargain on the price of an AC.

I'm gonna try to get a hold of a HVAC guy but until then i live in the mtns at 6200 feet so it doesn't get very hot in the summer and the nights are pretty cool, winters are very cold and i only run the flower room at night into the morning 9pm-9am. So i was thinking i wouldn't need the normal 3000-4000 btu per 1000w.
Another question i have a 10" max can fan pushing air through the lights. Is this enough power for 8 1000w's and should i be pushing or pulling air through the lights or should i have 2 fans doing both? Thanks for the help

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thatspoker422 said:

I'm gonna try to get a hold of a HVAC guy but until then i live in the mtns at 6200 feet so it doesn't get very hot in the summer and the nights are pretty cool, winters are very cold and i only run the flower room at night into the morning 9pm-9am. So i was thinking i wouldn't need the normal 3000-4000 btu per 1000w.
Another question i have a 10" max can fan pushing air through the lights. Is this enough power for 8 1000w's and should i be pushing or pulling air through the lights or should i have 2 fans doing both? Thanks for the help

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I am a HVAC guy. Need 2 fans for lights. Need 3 ton a/c. Get a HVAC guy and a mini split.

Thanks CJ i contacted an HVAC guy and he should be coming by Sunday. So as far as the lights go do i need 2 fans for more power because i can upgrade to a bigger fan or because you need one pulling and one pushing for equal air pressure? Thanks, tp

I know someone who cools 8k with one 10" max fan, but you can't duct more than two lights at a time, meaning a 4 way split from the fan, each ducting two lights at a time. Sketchy and messy, but doable. If your temps are always pretty cool where you grow, you can use 2 10" max fans pulling the air out, and 1 large intake fan blowing in cool air. Again, you shouldn't duct more than two lights together at a time, so each fan split two ways, each ducting two lights at a time. This will minimize heat build up.

I forgot this was a sealed room. An A/C would cost you more, but it will save you from the headache of setting up a big clusterfuck of ducting.

i already have the ducting set up with 1 10" fan pushing thru the light all in line( no split). The hoods have 10" vents for 10" ducting. The temp in the room gets up to 91 right now and will probably get to 95-100 in the summer. So my question is would a bigger fan or 2 fans( 1 pulling and 1 pushing) be better? Or would it not help much more than just having the 1 fan? Thanks,tp

I would get a 3 ton AC and get 2 10 inch fans 1 going through each run of 4 lights. You can NEVER have too big of AC and it leaves room for expansion at least. Look into a Friedrich 3 ton it;s a good brand for cold temps(mountain) and what not. Try and pull cold air through your lights from under your house and exhaust it out, IMO 86 degrees F is about max temps you want to run in your grow and that is with CO2, and I imagine your running that if your room is sealed up. good luck and happy growing. -BB

If you put a 3 or 3.5 ton a/c in an 8 light sealed room even with co2 burner you don't have to cool your bulbs with venting at all.
You can either use a split system or if you don't want to have an outside part of an a/c system involved you can go with a completely self contained water/freon cooled a/c..no need for copper piping, and splitting the system; much easier to install than a split system also.
But they go through water like crazy. You need a water in, water out, and condensation drain. If you pay for your water it's not economical but if you're on city water and not paying for it this is an option you may want to look at.

You don't want to have one fan pushing through 8 lights. By the time the air reaches the 4th light, its so hot its barely cooling the other 4. If your temps are at 91 now, I would bet you can get into the lower 80s simply by splitting the ducting to pull the air through 2 lights at a time. This would be the most economical answer. If money isn't an issue, then a huge AC is the most simple solution, and you could drop your temps far lower than 82 if you wanted to.

Hey Northwest Skunk, can you tell me more about the water/freon cooled ac please?

Hey bds,
Instead of using copper piping and freon to transfer the heat from your air handler in the room to the outside a/c split condensing/compressor unit like in a split system, the water cooled self contained unit uses freon and water in one complete unit. The one unit has a water in (your city water line), water out (this is expelled pressured water from the unit that needs to go into your plumbed drain that is now warm from removing heat), and a water condensate drain out (condensate water comes from the radiator on the a/c and you can drain this into the same drain the pressured water out goes into)

The water out is pressured so you don't have to worry about gravity flowing your water to a drain, but the condensate drain line isn't pressured so you either have to tie it into the pressured drain, or you can have the a/c set up high enough off the ground so the condensate gravity drains itself to your plumbed drain.
Or a third option is to use a condensate pump (about $30-$50 hardware store) to make the condensate drain pressured so it can flow up hill against gravity if needed to drain to your plumbed drain.

You can get these systems from 1/2 ton up to 12 ton and are very simple to install.
You need to put them on their own breaker. A 3 ton should be on a 30 or 40 amp breaker. You can get them either 120 volt or 240 volt. The 240 volt equipment is more efficient for energy usage.

Another cooling option is a unit called a swamp cooler. They come in single fan, double fan, three fan, or 4 fan. They only use air and water to cool, no freon, and don't have the cooling capacity as a true a/c but they are good for shows from 1 to 6 lights. The problem that can arise with them is that they use water to cool with so if your city water gets warmer in the warm summer months then the cooling power of the swamp cooler drops because of the warmer water. For these units to work well your water should be more around 45 to 55 f. Any warmer the cooling capacity of the unit diminishes quickly.

The top picture is a water/freon cooled a/c. that was set up in a sealed 8 light room with co2.
Similar units can be seen here:

The lower picture is a 3 fan swamp cooler that was set up in a sealed 6 light room with co2.
A 4 fan swamp would have been better in that room.