Calculating The Size of a Air Conditioner

[00420]

Need some help here:

I have been struggling with a heat issue in my sealed room. Here are the stats:
Basement style grow room 12'x8'x6'8"
I split this room into a VEG(7x8) and flower(5x8)

Veg is T-5 432watt light

Flower is 2-1k air cooled lights(sealed hoods with cool air and exhausting outside the room)

The way my basement was sent up(game room) the a/c that was already there(wall mount 6M btu). So I keep the a/c there and tried to use it. The flower and veg room have 2-6" fans transferring air between each other with a scrubber between the two. So my original thought was to run the 6M btu a/c to try and cool both rooms. That didn't work...the veg stayed ok at 75F but the flower stayed around 90-92F. SO then I went and bought a 15M btu a/c(wall mount) to hang in the flower room. After putting it in....it looked to big. But I figured that I needed the "big" a/c. Well the a/c cycles on and off with both rooms still exchanging air between them two. The only way I can get the rooms to stay stable is run the 15M and the little 6M in both rooms. The reason why is the BIG DOG a/c wont stay on long enough to cool the rooms down. I do have the a/c on low(speed 1) and still no help!

If I did the formula on this thread and adding up all the components between both rooms I'm at 10625 BTU needed. Now that is not counting the DH if needed. I would think the a/c would take care of that. If not I have a 65pint DH on hand if needed.

So should I take the 15M a/c back and get the 12M Btu??

Will I ever get both rooms to stay somewhat stable in the ideal temps??

i would go down to the 12 unless you plan on adding more light

if i remerber right the 65 pint DH is close to a 600 watt light and would bring you up to where u need to be but i dont think u will need to run it if u have the smaller a/c and even if u do run the 12kbtu with the DH u will be fine... whats your RH now?

it's ok for it to kick on & off but not a shit load..... also remember this is just the start of summer so keeping the 15 would not be a bad pick either.... it really comes down to your plans later 12,000 btu will do 3k light most the time but i have seen it do 4 and i have seen it choke with 3....

 

[Befri]

Thanks for the reply...

My RH runs around 55-60% when lights are on...and 65% when off.

 

[~Shhh~]

Thanks for the informative thread 00420!

Lemme just check I have this right...

Floor area is - 10 x 7 x 40 = 2800 (A)

Equipment in room:

Fan - 65w
Oscillating fan - 50w
2 x airpumps - 20w
2 x water pumps - 20w

So - 155w x 3.5 = 545 (B)

If ballast kept in room - 2400/2 = 1200w x 3.5 = 4200 (C)

Lighting - 2400 x 4 = 9600 (D)

Occupant - 1 x 400 = 400 (E)

Total load - 17545 Nearest AC BTU size = 18000BTU.

If I remove the ballasts from room, I should be able to use a 14000BTU correct? Will this size AC ensure that it runs throughout the lights on cycle?

How do you maintain night time humidity without a dehu?

Thanks in advance!

 

[00420]

if u keep the ballast in your room go with the 18... if u take them out go with a 15 that will give u a lil extra push on them 100+ days but yet still able to control your hum by usinging a slower fan speed on the days that it's 75-80

 

[CandyColas]

Great thread guys. Just a quick question. How do you mount window mounted A/C units inside a home? My grow room is in a spare bedroom but I've sheetrocked over the window and completely lined the inside of the room with poly so there is no access to the window. I wouldn't want to hang a shaker unit from the window anyway as I feel this would be a giveaway to my op. Do you mount it to an inside wall? If so, how do you vent that hot air? What about split A/C units? Are these as efficient as a window mount? I know that they are super quite. At least the part that is inside the room.

Thanks for all the help!

 

[GorillaGrower]

candy.. if your in a spare bedroom.. the best bet prob would be the window..

usually say if your adding a window unit to a room ..often times the rooms walls were constructed for the op (say in a basement).. you just knock out a hole and frame it up for the A/c. The back of the A/c where the heat comes out.. dumps into spare room (say the laundry area).. but in your case i imagine the whole you make would point the rear of the unit into a bathroom or hallway.. which probably wouldnt go over well.. with the misses.. landlord.. etc.

depending on how many lights your using.. you could do two things beside the window unit in the window... if one light or a modest setup... a portable "could work" and if more lights.. using a mini split would be a perfect solution.. especially if you want that window locked tight.

and yes mini splits are prob the most efficient but most expensive application.. think of a whole house A/c unit but "Mini"

 

[Guest 18340]

Great thread guys. Just a quick question. How do you mount window mounted A/C units inside a home? My grow room is in a spare bedroom but I've sheetrocked over the window and completely lined the inside of the room with poly so there is no access to the window. I wouldn't want to hang a shaker unit from the window anyway as I feel this would be a giveaway to my op. Do you mount it to an inside wall? If so, how do you vent that hot air? What about split A/C units? Are these as efficient as a window mount? I know that they are super quite. At least the part that is inside the room.

Thanks for all the help!

Check out hoosierdaddys thread on building ac boxes. That thread is golden.
As for mini-splits, I have a 9k btu unit that has heat mode and uses inverter technology and was delivered to my door complete (and I mean complete-pre charged with r410, line set with flared connections so all you need are wrenches instead of soldering, power lines, etc) for $1100.
I can tell you from experience that mini splits are ultra efficient, especially the ones with inverter.
Hope this helps...Evl

 

[CandyColas]

Check out hoosierdaddys thread on building ac boxes. That thread is golden.
As for mini-splits, I have a 9k btu unit that has heat mode and uses inverter technology and was delivered to my door complete (and I mean complete-pre charged with r410, line set with flared connections so all you need are wrenches instead of soldering, power lines, etc) for $1100.
I can tell you from experience that mini splits are ultra efficient, especially the ones with inverter.
Hope this helps...Evl

Evl,

You're the man. That's twice you've helped me out in the last 2 days. What brand and model is that split? That sounds like a great deal. I've been looking on my local craigslist and have found some pretty cheap split systems but I'd assume that they need to be recharged and the installation can probably be a pain in the ass for a used system. I'm going to have to check out this ac box for sure though. I found a good 10k BTU window shaker for $100 that I might pick up.

Thanks again bro!

 

[PrinSeshJasmine]

.

 

[In Vino Veritas]

those splits are hot shit.. i love them..

great thread.

 

[pugnacious]

Heres a PDF I found that gives the formulas to calculate room size and energy consumption. So if your fantasizing on a grow that needs a 5 ton ac. According to this chart it would be around 18kw.




http://www.ptsdcs.com/whitepapers/23.pdf


Im posting this so the AC/Electric gurus could verify it.

 

[ilovethewest]

i need to get a dehumidifier asap. portable air conditioners can get the same amount of pints per day as the dehumidifiers i was looking at, and cost about the same, but offer "12000"btu of cooling, and 65 pints/day of dehumidifiering. the room:4x6x7 master closet. running 2x600w hps lights in 2x cool sun 8in reflectors, with a vortex 750cfm cooling them. that fan first goes through a carbon scrubber, and then gets vented into the house. so with my room getting vented, and no co2, should i even think of giving my plants some cooling, or should i jsut stick to the basics of a dehumidifier? any body use a portable "vented" air con before, and if so what was your experiance? should i get one? thanks

 

[Wariat]

How much m3/h I need to cool 400 w hps ??

I want to put my light 10 - 15 cm to my plant.

Thanks and sory for poor eanglish

 

[Coco4Coco]

Anyone build a box for their dehumid to vent the HOT exhaust that comes out...
mine heats up the room by 10 deg F?

I am not talking about putting the whole unit in a box
but just to enclose the front where the hot Exhaust comes out
and duct it out of the room...

 

[hydr1]

Hey guys...Im shopping for an AC unit.

my room is

9 x 15 x 7 ' I have 18000 BTU worth of ballasts and lighting.

Im running co2 so I only want to be down to 75-80 degrees...I was looking at a stand alone 12,000 but I wanted tot alk about it before I jump. I have a spot I can hang a window unit but I think it would be sketch to be running a window unit while its 30 degrees outside. I also have a 6" duct to exhaust I can vent a standalone out if I got a single hose.

Humidity shouldnt be a factor as I have a dehumy. Thanks for any input

 

[BUBBA LUVSPONGE]

im gonna need this thread this summer ...nice job

 

[Broken Gizzard]

AC Sizing...

AC Sizing...

Although the numbers are rounded and the guidelines generalized, 00420 is correct.
I have been designing/engineering/selling/project managing high-tech heat exchange systems (HVAC) for 25+ years, both dry and wet-side systems.

I am very glad to see this post, as the two most under-engineered systems in the grow room seem to always be electrical and climate control. With the mass of marketing that growers have heaped upon them by manufacturers/distributors, it is difficult to for a grower to know just which direction to turn. Remember, with mechanical equipment, 'expensive' doesn't always mean 'good', usually just 'overpriced'.

Hat Tip to this thread

 

[ilovethewest]

broken gizzard, stay around, ill have so many questions for you in a hot minute. i like having "professionals" around here.

 

[SmokinErb]

So this is an older thread, but excellent nonetheless.

Anyway, I plan on installing a window AC in my grow room. It's in a spare bedroom. Upstairs. In a place with central air. My concern is how suspicious it's going to be? The central air unit is located directly under the spare bedroom window on the 2nd floor =/

Too suspicious?

 

[Broken Gizzard]

No...not at all...

No...not at all...

So this is an older thread, but excellent nonetheless.

Anyway, I plan on installing a window AC in my grow room. It's in a spare bedroom. Upstairs. In a place with central air. My concern is how suspicious it's going to be? The central air unit is located directly under the spare bedroom window on the 2nd floor =/

Too suspicious?

Over the years I have designed installations for (older) homes that simply have no way of physically getting a duct to a converted attic etc... Sometimes a window AC is the only solution available...and this is also a good excuse for having it there.