1800watts of led's in a 18x18x8' sealed room... think I will need an A/C?

[mikeross]

I plan to run 1800watts of LED's in a veg room that is 18'x18' with 8' ceilings. Room stays around 67 degrees all year long. I want to keep it sealed and burn Co2. Do you think I can get away without running an A/C?

 

[LexLuthor]

Yes.

 

[Moe.Red]

Put me down for yes, it can be done but you will have wild environmental swings that will likely cause plant stress. I would expect temps to reach 90*F + not to mention the RH swings when the lights go off.

I run 4x8x8 with 1200W LED and and CO2, I would not be able to keep the plants happy without my mini split in a sealed room. It runs a LOT

 

[Arkos]

In a well sealed room with a burner, I think yes but it won't have to work too much.

2000w Leds here same size room, no burner, sealed like a crackhouse, 2000w heater to reach 84f

 

[mikeross]

In a well sealed room with a burner, I think yes but it won't have to work too much.

2000w Leds here same size room, no burner, sealed like a crackhouse, 2000w heater to reach 84f

So no issue huh... nice. This room is going to be sealed tight, no a/c... there will be an exhaust connected to a humidistat to exhaust only if humidity reaches whatever I set it to but I plan to keep it hot and humid in veg. Might need a dehumidifier too. I like to purge my sealed rooms when the lights go out to help with the humidity spike and bring some fresh air in just incase the burner isn't combusting properly.

How high does your humidity climb in your setup?

 

[Keepitgrowing247]

So no issue huh... nice. This room is going to be sealed tight, no a/c... there will be an exhaust connected to a humidistat to exhaust only if humidity reaches whatever I set it to but I plan to keep it hot and humid in veg. Might need a dehumidifier too. I like to purge my sealed rooms when the lights go out to help with the humidity spike and bring some fresh air in just incase the burner isn't combusting properly.

How high does your humidity climb in your setup?

Just curious, you said exhaust only correct ? So when you say "bring some fresh air in" where is that coming from ? Assuming you're completely sealed with no leaks..
I'm trying to avoid an intake on my completely sealed room and only have an exhaust to dump at night for the humidity spikes and excess c02 from being in big living soil beds..
I'm just wondering if I'll have to worry about "stale" air over time since my Mitsubishi mini split only recirculates it doesn't actually bring in fresh air and my space is extremely sealed.

 

[Moe.Red]

Just curious, you said exhaust only correct ? So when you say "bring some fresh air in" where is that coming from ? Assuming you're completely sealed with no leaks..
I'm trying to avoid an intake on my completely sealed room and only have an exhaust to dump at night for the humidity spikes and excess c02 from being in big living soil beds..
I'm just wondering if I'll have to worry about "stale" air over time since my Mitsubishi mini split only recirculates it doesn't actually bring in fresh air and my space is extremely sealed.

This is photosynthesis:

6CO2 + 6H2O → C6H12O6 + 6O2.

Nothing more, nothing less. The only gasses there are CO2 (input) and O2 (output). Any other gas is rejected by the plant in this process.

CO2 is measured in PPM - like 400 in normal outdoor air. Think of 1 million white ping pong balls, and 400 red ones. Mix them up, and try to find the red ones. There just isn't a lot there. Sealed rooms require CO2 injection to work. Excess CO2 (what, maybe 2000 PPM?) is still incredibly low overall as a percentage of gas and will get used up by the plants in short order anyhow. And what made it excessive in the first place? You must have been injecting too much. I don't get that part. Some commercial grows run waaaaay higher than we do - the extra cost of CO2 is apparently justified financially. More is not worse is my point.

O2 is kinda irrelevant overall except in the root zone. But O2 takes care of itself via photosynthesis, no need to add or remove it for plants to be happy in a sealed room. Nitrogen makes up by far the largest part of the gasses in the grow chamber, and for our purposes is essentially inert. On the timescales we work with, nitrogen fixing into the soil or plant really doesn't happen, and if it did it would be completely overwhelmed by nutrients added.

So what is there to exhaust? What is "stale?" If temp and humidity are controlled and you have a carbon filter, there shouldn't be anything there to detect as stale except maybe terpenes or if you are not running a clean grow, dead or dying plant tissue (or something in bad soil?). Get dead foliage out of there before it begins to decompose, sealed room or not. Even then, dying plant matter does not impact photosynthesis one iota unless it is so bad it starts displacing or re-arranging the CO2 / O2 / N ratio. Not likely.

I'm sure there are particles of this or that - offgassing of plastics, possibly buildups of minor compounds, but I believe all that gets neutralized just fine by a carbon filter and simply opening the room up when the farmer is working in there.

I see no reason to exhaust as an ongoing rule, but I can see the benefit of sucking out some air 20 minutes after lights out if you want to manage RH. But the makeup air has to come from somewhere, which means you have to find a clever way to break the seal in the room during this process. I just don't see how it is worth it. Probably one of those things that might make us feel better as farmers, and the plants don't give 2 craps about. Now, if your dehumidification cannot keep up with respiration, then you need to do something like exhaust or you will be a candidate for PM and can ruin the whole grow.

The other reason to trade some air after the lights go off is to get the proper day/nite temp spread. Depending on your setup, lung room, things like that, you might get some benefits if you can get a cooler nite time temp.

So many variables...