Yet ANOTHER mini-split A/C question

I'm in the process of building a new house with a detached garage. The garage will also have an apartment above for the occasion guest.

I'm going to have a 200 Amp sub panel located in the 15'x15'x10' grow room. I will have a mix of 120v and 240v outlets placed around the room. I will also have a 4-burner CO2 generator as well as Quest dehumidifier.

I'm in a NON medical State that sees mild-ish winters and HOT HOT HOT HUMID Summers. Mostly upper 90's in to the low-100's for MOST of the summer. 2 walls are exterior walls and all 4 walls and ceiling will have spray foam insulation. I'm also going to install heavy duty black plastic and then Purple drywall on the interior to ensure it's well insulated, resists mold/mildew and also sealed as much as possible.

I plan on running LED lights and possibly some fluorescents for germination/cloning. This is going to be a small grow. Less than 10 plants MAX. I don't see using more than 2 or 3 LED lights EVER.


I'm looking at installing a 12,000 BTU mini-split. Do you think this is enough or should I go for the 24,000 BTU (2 ton) unit?

Any advice would be GREATLY appreciated!

its better to have enough and not need it, than to have to little and need it!!

Paging RIU HVAC expert @Gonejha - can you help this gentleman out?

I'm a hvac refrigeration mechanic by trade. I would install an tomorrow and half or two ton unit with a digital scroll. This will allow the unit to modulate on demand and allow better control of both temperature and humidity. Let me know if you have any more questions

" ton and half or two ton unit..." lol

How many watts are your led, how many pints is your dehus, how many btu is your burner?

You need to add up your btus, if you over size you will have humidity problems due to short cycling. Remember you can get odd sized a.c. units

Gonejha said:

How many watts are your led, how many pints is your dehus, how many btu is your burner?

Click to expand...

I'm looking at the following:

THANKS Gonejha for the assistance!!!

1. Fluence SpydrX Plus LED = 660w x 2 lights. 1320w total
2. Quest 205 dehumidifier = 205 pints per day
3. 4-burner CO2 generator LP gas = 9,052 BTU/hr

I will also have a chiller, fans, pumps, etc... inside the room as well.

I have no reason that I can think of for the Quest 205 sized dehumidifier. Should I go smaller?

Realbax said:

I'm a hvac refrigeration mechanic by trade. I would install an tomorrow and half or two ton unit with a digital scroll. This will allow the unit to modulate on demand and allow better control of both temperature and humidity. Let me know if you have any more questions

Click to expand...

What is a 'digital scroll' ???

Lights = 4550 btu
dehum = 1000 btu est.
co2 gen = 9100 btu
building = 4 - 6000 btu depending on glass
misc. pump and ect = 1500
estimated 22150 btu needed removed at peak load , two ton min. IMHO

digital scroll / inverter drive tech is basically the machines compressor uses only the power need to maintain the temp requested, ( if you only need to remove 14kbtu it ramps down or up to the power needed for the job)

HydroDawg421 said:

I'm in the process of building a new house with a detached garage. The garage will also have an apartment above for the occasion guest.

I'm going to have a 200 Amp sub panel located in the 15'x15'x10' grow room. I will have a mix of 120v and 240v outlets placed around the room. I will also have a 4-burner CO2 generator as well as Quest dehumidifier.

I'm in a NON medical State that sees mild-ish winters and HOT HOT HOT HUMID Summers. Mostly upper 90's in to the low-100's for MOST of the summer. 2 walls are exterior walls and all 4 walls and ceiling will have spray foam insulation. I'm also going to install heavy duty black plastic and then Purple drywall on the interior to ensure it's well insulated, resists mold/mildew and also sealed as much as possible.

I plan on running LED lights and possibly some fluorescents for germination/cloning. This is going to be a small grow. Less than 10 plants MAX. I don't see using more than 2 or 3 LED lights EVER.


I'm looking at installing a 12,000 BTU mini-split. Do you think this is enough or should I go for the 24,000 BTU (2 ton) unit?

Any advice would be GREATLY appreciated!

Click to expand...

1 Ton (12000 btu) is more than enough.

HydroDawg421 said:

I'm looking at the following:

THANKS Gonejha for the assistance!!!

1. Fluence SpydrX Plus LED = 660w x 2 lights. 1320w total
2. Quest 205 dehumidifier = 205 pints per day
3. 4-burner CO2 generator LP gas = 9,052 BTU/hr

I will also have a chiller, fans, pumps, etc... inside the room as well.

I have no reason that I can think of for the Quest 205 sized dehumidifier. Should I go smaller?

Click to expand...

A 205 is a big mo fo
I’m sure the 105 is overkill for you
I have a 105 and 5000watts of light plus CO2 etc

I just hooked up my 12,000 btu split unit! Most of them have a dehumidifier on them. I must say I will never go back to window/wall, or stand up units. These mini splits r super quiet! U can hear my inline fans over the ac. After I hooked it up it was so quiet I didn’t even realize it was on, till I stood under it. 15x15 is 225 square foot. It’s usually 500 square foot to a ton, unless u live in a high humid region as mine, we have to go 400 square foot per ton.

I got mine cheap off Craigslist, 250$! 2009 Sanyo 12,000 btu r-410 120v. The inside handler was full of dirt and mold. I had to completely pull apart the inside handler, take off the electronics, pressure wash, then bleach the hell out of it. Dried it out in the sun. When I took it apart I seen the electronic remote pcb board connector was corroded and not making contact. So I pulled out my trusty soldering iron, removed the connector off the pcb board, and soldered the wires strait to the board.
The outside unit looked brand new, and still had the Freon in it. So I didn’t have to call my ac guy to come charge it.
Didn’t come with wires, nor copper lines, so I had to make all my own from Home Dickpot and Lowe’s. It’s always fun working with the flare tool!
Took me about a week of cleaning, planning, wiring, and installing. I am not a hvac. Plus I have a full time job, 6 days a week! Rember this is 120v. So the outside disconnect most of them is 240v. U will have one side of the outside disconnect not hooked up. Make sure u get a dual pole single trow switch for your inside handler disconnect.
Any questions on hooking it up, we here for u brother!

I wouldn’t run the co2 burner. It creates heat. If u must go co2, I would use the injection system. U don’t need the co2 if your only doing 10 plants. I have a old guru. When I went to him asking all these questions, he told me to stop and take a breather! He told me this advise, and I will always remember this! Quote: ( Growing is only as hard as u make it!)
Keep it simple! Keep your temps right! Keep your air fresh! Keep your soil moist! That’s all the great needed in the beginning!

Wait until you price out the cable to feed a 200amp setup. A 100amp is overkill for the setup you plan.

Hey guys been wondering. .....would the outside unit of a split a.c. work in a big loft(lung room).......?

Greenhouse;save said:

Hey guys been wondering. .....would the outside unit of a split a.c. work in a big loft(lung room).......?

Click to expand...

Yes , but they kick out a lot of heat and making it harder to kool themselves n making them less efficient

diamonddav said:

its better to have enough and not need it, than to have to little and need it!!

Click to expand...

x2 and I cannot emphasize this enough.

Got 2 15,000 BTU window units, just in case I'd need them. Just one was alright for my 4400w grow most days, however during those 120+ degree days the second one became necessary. I find myself using the 2nd A/C for 2-4 weeks out of the year.. yet despite that it was still worth the money because I would not be able to grow during the summer if not for the extra AC. If nothing else, when my primary AC craps out I have another one ready to go.

The A/C is the one thing you should be happy to go overboard on. Fuck the lights, nutrients, soil/soilless medium, CO2, etc. If you can only go overboard on one thing, make it your AC and trust me on that one. You absolutely do NOT want to be 5 weeks into flower in the middle of June/July with 85-90 degree temps and an underpowered AC running 24/7 doing nothing for you.

I'm a big fan of over kill when it comes to minisplit size. I have a 3 ton just cooling 3 DE lights It never struggles. Plus it gives me room for expansion.