Could someone help mini split.

[Dankdad64]

No, I didn't pull you up when you misinterpreted my last post, but this isn't applicable.
The aircon sizing based on area, makes a number of presumptions. Most around the structures heat gain. Things like number and size of windows. Outside walls, North or south, roof, floor. The air exchange likely. Number of occupants and there tasks. All is presumed when people don't care to do it properly.
In this space, there is a large heat source, and also extraction. Factors of greater importance than the usual presumed one's. If this grow was pushed in a room half the size, the requirement would barely change. You still must cool the same amount of air going in. Enough to account for the heat gain of the grow. It's 8000w of gain, or 27500btu to remove. Then you could start looking at the room size needing 9000 because of building gain. Which is nonsense, because it's not a sealed room.
This needs looking at from a commercial ahu plant prospective. Where a building needs a volume of air blowing in, at a certain temperature. This ahu is the garage. Though the plant is likely portable and pointing at the rooms intake duct, it's the same principle.

The 6252a amemometer is $20 and a typical wind speed measurement device. You can put it in a duct, and tell it the duct size. Allowing it to see the air speed, and calc duct flow. Most of us guess airflow, and tend to think the sticker on the fan is achieved. Which is far from the truth. This would be a reasonable way to find cooling requirements for the volume of air passing through. The size of the floor isn't a big concideration, as building gain isn't a big part of the problem.

Thank you for replying. I contacted a place, tech said he's fitted 20 rooms so far. Ended up recommending a 12000 btu mini split.

 

[Turbo5]

I have a 8 x 8 room almost 9 ft ceiling. I have 7980 watts of equipment lights,fans intake ect. I want to put in a mini split 9000 BTU. Will this work?

Similar setup to yours. I have a 12k btu split unit self installed, concrete floor with insulation on walls. Running 1800w in led, 500w dehumidifier fans and 8”exhaust. I only really run AC between July -Sept. I have to say that the unit basically runs constantly ( like 5 mins on 5 off, especially when it’s ripening time and you want lower temps) to maintain the set temp which of course is an increase in the electric bill. I feel if the room was completely sealed it would be much more effective but I don’t want to do co2 yet. Just something to consider. If I set the room temp to 82-84 it is much more efficient. Hope this helps.

 

[Ca++]

I have a 12000 portable. Often it's taking in 28c air, and chucking out air in the low 20s. It moves a volume of air that might match a 200mm extract system. Might. Because often peoples extract is nothing like they think it is.

Ideally that low 20s air would want distributing around the room, with ducting. Straight to the back of circulating fans, who's job is to mix the cold, with warm from the room.

Until it's actually installed, it's hard to really know. Just having the right numbers, doesn't mean it's being utilised optimally. It's good to find someone that's experienced enough, to have seen a few attempts though. He should have a good average idea. In this application.

 

[Rockchild]

I have a 8 x 8 room almost 9 ft ceiling. I have 7980 watts of equipment lights,fans intake ect. I want to put in a mini split 9000 BTU. Will this work?

I ran a 9k btu mini split 8x5(X8Ft ceiling) in a SEALED room with 2 x1000w hps. This is in Florida, in a room built into the corner of a garage. The ballasts were outside the room. Only a wall fan, dehumidifier and co2 tank/sniffer in the room. 9k btu was mor’e than enough.
You mention 7800watts of equipment…such as? Lights are the only heat producers you mentioned. Fans/intakes/etc don’t produce heat.…
3.5 btu cooling for every watt, 2x1000w hps=7k btu.
When lights are on (producing heat) the AC keeps temps/humidity in check. When the lights go out I have a dehumidifier that kicks on. The dehuey produces warm air, which makes the AC kick into cool, which brings down humidity, which shuts off the denjoy, etc, cycle all night. That’s a SEALED room, no air in or out.

 

[Rockchild]

Similar setup to yours. I have a 12k btu split unit self installed, concrete floor with insulation on walls. Running 1800w in led, 500w dehumidifier fans and 8”exhaust. I only really run AC between July -Sept. I have to say that the unit basically runs constantly ( like 5 mins on 5 off, especially when it’s ripening time and you want lower temps) to maintain the set temp which of course is an increase in the electric bill. I feel if the room was completely sealed it would be much more effective but I don’t want to do co2 yet. Just something to consider. If I set the room temp to 82-84 it is much more efficient. Hope this helps.

Thats called “short cycling“. A property sized AC wouldn’t turn on/off as much and therefore keep humidity/temps more stable.
You on have 1800 watts, 12k btu is waaaaaay oversized. A 6k btu mini split would be perfect for your setup…

 

[Ca++]

It's nice that more compressors are being used, that are actually variable speed. It's still a bit too new for me to pull up a chair to the discussion table, but a 12k won't quite turn down to 6k I don't think. However, a 9k would. So it wouldn't cycle much at all. However, I have not seen window bangers use EC compressors yet. I have seen them in clothes driers, and rotary compressors at that. Single room splits are commonly using them now. It's not quite the market standard, but I think the current eco regs have about given us the good stuff.

Last year I saw a 12k split at the cheap end of the market, that was actually Samsung iirc (who make EC rotaries for sure) making a quick connect split with the right bits, without making a song and dance about it. They just slipped the fact it was a DC motor into the brochure, with no talk of why.
Having these things able to turn down a third, without needing to stop, is very useful. Restarts are often timed to not happen for a good few minutes (my dehu is 20) and that can be too long. While stop/start noise is attention grabbing. When you could have a constant reduced noise by slowing it. Building control love that, and I'm getting pretty stoked to