Central Heat and Air? Sealed Grow Room?

I have a quick question and must openly admit that I'm new to growing in a sealed environment. I've previously have used HPS lights with Intake and Exhaust set-up. However, I'm converting over to a completely sealed room
using co2.

My question is, in a sealed environment with HPS, obviously supplemental AC is needed whether it be through small portable units two hoses n the back going out and sealed tight, a mini-split system, a window unit, and so on. However, my question is; WHAT IS WRONG WITH USING THE CENTRAL HEAT AND AIR VENT in the roof of the room?

I've read previously it has something to do with it creating a positive pressure. However, I'm unsure of what would exactly be the difference in a vent in the ceiling blowing in fresh cold air or a portable unit in the corner doing the same thing.

I still plan to either do a window unit or mini-split, however I have to know the answer to this. Because if I could let the Central Air vent cool the room, I would have a lot less power usage to worry about with the generator.

Thanks for any help or input anyone has!

Your central ac/heat thermostat is not in your grow room, so how would it know weather to cool or heat. Buy a unit just for your grow. Btw, do NOT buy the active air 14k dual hose ac, it's utter garbage. Couldn't cool a 8x12x7 1800w flower room below 77* no matter what I triwd.

DemonTrich said:

Your central ac/heat thermostat is not in your grow room, so how would it know weather to cool or heat. Buy a unit just for your grow. Btw, do NOT buy the active air 14k dual hose ac, it's utter garbage. Couldn't cool a 8x12x7 1800w flower room below 77* no matter what I triwd.

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Thanks, that's what was confusing me. So with that said, if if you were to leave the vent blowing rather then sealing, when the air decides to kick on and gets the signal from the thermostat, will this act as supplemental air to the room? It just wouldn't be consistent?

As for 14k Active Air's, I already ruled those out. Going another route, actually the more expensive, but much more efficient route. I'm hoping 24k of btu from a mini split or window will be enough to keep a 10x12 and 3x4 area down to temp. Will also have fan/carbon filter on ground scrubbing, with fans spread throughout the room. Co2 levels will be kept at 1200-1500 ppm.

It will only help to a degree. I grow in a basement setting in a small commercial building. On the hot fays, 82*+, I'll kick on the main buildings ac unit and keep it at 77*. I have 2 vents that will blow the air down stairs to help with the cooling. I've never in 4+yrs of growing ever needed the need for any heat. My 1800w veg room, or 1800w flower room hood exhaust can help with that. Now this fall/winter I'm putting up my ac and going to try and use the cold air from outside. Hope I can dial it in with out too much temp fluctuations.

BusinessManTexas said:

Thanks, that's what was confusing me. So with that said, if if you were to leave the vent blowing rather then sealing, when the air decides to kick on and gets the signal from the thermostat, will this act as supplemental air to the room? It just wouldn't be consistent?

As for 14k Active Air's, I already ruled those out. Going another route, actually the more expensive, but much more efficient route. I'm hoping 24k of btu from a mini split or window will be enough to keep a 10x12 and 3x4 area down to temp. Will also have fan/carbon filter on ground scrubbing, with fans spread throughout the room. Co2 levels will be kept at 1200-1500 ppm.

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size the AC to the lights,not the size of room.
for instance
a 1000 watt double end bulb needs a minimum of 4500 btus

BusinessManTexas said:

Thanks, that's what was confusing me. So with that said, if if you were to leave the vent blowing rather then sealing, when the air decides to kick on and gets the signal from the thermostat, will this act as supplemental air to the room? It just wouldn't be consistent?

As for 14k Active Air's, I already ruled those out. Going another route, actually the more expensive, but much more efficient route. I'm hoping 24k of btu from a mini split or window will be enough to keep a 10x12 and 3x4 area down to temp. Will also have fan/carbon filter on ground scrubbing, with fans spread throughout the room. Co2 levels will be kept at 1200-1500 ppm.

Click to expand...

That window rattler will run a negative pressure situation. More then you think! In my old place. It would close the door behind you! That was with 1 25K AC "rattler"...4 1K Bloom lights on movers and 20 4ft T5's with 1 600 for veg.. 18X36.

Mini splits for you.

I run a central system in a dedicated standalone building now. The only time it creates any pressure issue (96% efficient) is during heating in winter. Due to the amount of lights and generated heat.....That only happens at night!

I run off of one 110 window unit and it will get up to 80f in the garden with tx heat.Last winter I only needed heat for 2 storms though.Seems like the summer of 2011 out there, so no outdoor grow this year.

how will your ac know to kick on if the rest of the house is 70f and your room is 90f?

Dr. Nick, is your statement of 4,500 btu's per 1,000 watts just your preffered method, or scientific? Reason I ask, my books call for 4,000 btu's per 1,000 watts. I'm trying to work with what I have rather then going deep into my pockets. As of right now I have (4) Champion Inverter Generators at 2,800-3,100 surge, brand new in the box. I'm kind of ruling against the mini-split, due to installation and the fact that I'm not going to be at this spot long.

Instead, I'm looking at the following alternative.

(4) Champion 2800 / 3100 Generators - (2) Powering 5k worth of lights. (1) Each Powering a 12,500 BTU Window Unit.

This will leave me with an extra wattage on the light end to power fans and such. This will also leave me room on my ac Generators, while not having to work them at full load.
Four generators running burning 1.8-2 gallons every 6 hours. I'm looking at $500.00 a month for a stealth operation. The four inverter generators are really quite, but will be sound proof after venting them good in a sound proof box. They will be non-existent to the ear.

Rather then mounting the two window units in the window for stealth and security reasons, I will be removing the door to the bathroom (inside of this room.) There I will mount a piece of plywood to replace the door with two ac cages on the back (bathroom side of the plywood.) Slide my two 12,500 BTU - units in. Seal everything up, double seal, and seal a third time. I will also be putting fans on the bathroom side moving around air.

Then I can utilize both AC units when needed, and only one when two aren't needed, to save fuel on the generators. The generators are also powered by remote start / shut-off. They will have large tanks tapped in to the fuel system, should only need filled up, every few days of running. All in all, I should have 25,000 BTU's of cooling air, the units also have dehumidifiers. I will have 4-5 fans mounted on the wall circulating air, along with a scrubber and fan on the ground circulating co2. I'm hoping to really seal things up and be able to keep co2 between 1200 and 1500 ppm.

So as of right now this is the most efficient way I can think of to work with what I have.

So a central air unit want cool a closed grow room? Surely it should keep heat down in mid 80s. I mean I have had heat up to 95Degree in current area. Which has no air flow n a hot water heater in the small 4 x 12 area running 600 Watts

Seems it I keep it below 800 Watts it’s got to better than what I have