Sealed room AC sizing

firsttimeARE

firsttimeARE

Well-Known Member
So im going with Mitsubishi H2i heat pumps system.

My room has 1 window double hung thats blanked off with 1" foam and plywood.

Floor Room is 12x10x8

Has 1,360w and a dehumidifier in it

For a MSZ-FS wall unit they only make a 9k and 6k.

Simple math of 3.41btu per watt says 6k is enough

Just wondering for those who have these units experience
 
firsttimeARE

firsttimeARE

Well-Known Member
The MSZ-FS06NA submittals say max cooling at 95F is 9k btu and minimum is 1700 but its rated for 6k. I dont understand how it can cool greater than its rated capacity.

Heating a good rule where I live is 50btu per square foot so I know im good there. This is rated at 5900 btu at 17F
 
MidnightSun72

MidnightSun72

Well-Known Member
firsttimeARE said:
So im going with Mitsubishi H2i heat pumps system.

My room has 1 window double hung thats blanked off with 1" foam and plywood.

Floor Room is 12x10x8

Has 1,360w and a dehumidifier in it

For a MSZ-FS wall unit they only make a 9k and 6k.

Simple math of 3.41btu per watt says 6k is enough

Just wondering for those who have these units experience
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Ya you are figuring it out exactly correctly. So what I would do is figure out your BTUs based on the watts of every single item in the rooom. This includes oscillating fans, chillers, pumps, intake fans. Literally anything that uses watts that's actually inside the room. So this does not include your air conditioners watts. The. You take that wattage number and multiply by 3.41 as you said already.

so for your room let's say you are actually around 2000W once you include dehumidifer and fans etc. So 2000x3.41= 6820 BTU

then the last thing to do is to account for the BTUs required to cool a room that size in the summer and add those BTUs. For your room size for example 8000 btu would be Ok but 10-12 probably better. You don't want the AC at its limit for BTU all the time.
 
firsttimeARE

firsttimeARE

Well-Known Member
Oh yeah forgot aboht the chiller does about 800w. Its in my veg room. My veg room only has about 650w of light. Was thinkinf a 6k in there and maybe a 9k in the flower room.
 
redi jedi

redi jedi

Well-Known Member
If your grow room is already within a climate controlled room...like a house...you dont need to add that on top of heat generated by lights and such.
 
firsttimeARE

firsttimeARE

Well-Known Member
redi jedi said:
If your grow room is already within a climate controlled room...like a house...you dont need to add that on top of heat generated by lights and such.
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Yeah so I m putting a 12k in the big open space of my basement approx 700 sq.ft.

I know 400sq.ft. for every 1 ton rule of thumb bht not sure if that applies to basements.

Was gonna do 6k in veg and 6k in flower and 12k for rest of basement.

6k seems overkill for my veg room. May forgo the AC in veg room. Not sure.

Trying to keep my condenser under 60k
 
MidnightSun72

MidnightSun72

Well-Known Member
firsttimeARE said:
Yeah so I m putting a 12k in the big open space of my basement approx 700 sq.ft.

I know 400sq.ft. for every 1 ton rule of thumb bht not sure if that applies to basements.

Was gonna do 6k in veg and 6k in flower and 12k for rest of basement.

6k seems overkill for my veg room. May forgo the AC in veg room. Not sure.

Trying to keep my condenser under 60k
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I don't use any AC in my veg room. It gets up to 78-80 max. And when I open the door it drops to 73-75 quick.
 
firsttimeARE

firsttimeARE

Well-Known Member
YeAh imm a go with the 6k and nothing for my veg. If i need to ill add a transfer fan to move air between the two rooms.

This should be plenty.
 
DoubleAtotheRON

DoubleAtotheRON

Well-Known Member
If you're going sealed with CO2?.... calculate all your BTU's, and then double it for your AC unit. If you come up with 12,000 BTU's , you need a 24,000 BTU unit/2 ton..... and SalgoodMan. Been there, and done it.. had to upgrade to a 3 ton/36,000.
 
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redi jedi

redi jedi

Well-Known Member
DoubleAtotheRON said:
If you're going sealed with CO2?.... calculate all your BTU's, and then double it for your AC unit. If you come up with 12,000 BTU's , you need a 24,000 BTU unit/2 ton..... and SalgoodMan. Been there, and done it.. had to upgrade to a 3 ton/36,000.
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I think its too general to say add up your btu and then double it. For a commercial grow in warehouse that doesnt have any climate control, that may be accurate, but for the average person growing in their home its way overkill unless they live in Death Valley.
 
firsttimeARE

firsttimeARE

Well-Known Member
Thing is i wanna target 85F for my room temps.

I have a 7600k window unit that keeps the room at 75F easily ebough and that was with a chiller in the room. I was exhausting though.

My concern against oversizing is it wont run long enough to remove humidity
 
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A

Apalchen

Well-Known Member
They are inverter compressor meaning you can oversize with no Ill effect.
The most simple way to figure cooling for a grow room is 6000 watts per 1000 watts of lighting. This give you enough extra btu to cool any dehueys, fan, heat load of the room etc.
I have installed several mini splits going off this formula and it always works, and if I had listened to people saying do the 3.41x watts I would have been undersized. If I had listened to my AC guy I would have been undersized.
The price difference in upsizing splits is usually only a couple hundred dollars and will be well worth it when you can fully control your temps instead of the AC not keeping up or barely keeping up.
 
A

Apalchen

Well-Known Member
firsttimeARE said:
Thing is i wanna target 85F for my room temps.

I have a 7600k window unit that keeps the room at 75F easily ebough and that was with a chiller in the room. I was exhausting though.

My concern against oversizing is it wont run long enough to remove humidity
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You should never rely on your ac for humidity removal, they simply don’t work that well for that especially when you need them too. When the lights go off you won’t be cooling your room, and that’s when the humidity spikes.

I have my acs running full capacity, when the lights are on they run full blast and I’m still using 4x70 pint dehuey in one room right now to keep it under 60percent.
 
firsttimeARE

firsttimeARE

Well-Known Member
Apalchen said:
You should never rely on your ac for humidity removal, they simply don’t work that well for that especially when you need them too. When the lights go off you won’t be cooling your room, and that’s when the humidity spikes.

I have my acs running full capacity, when the lights are on they run full blast and I’m still using 4x70 pint dehuey in one room right now to keep it under 60percent.
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Yeah Im still going to use a dehumidifier. But if the AC can do the job lights on why run both
 
firsttimeARE

firsttimeARE

Well-Known Member
Apalchen said:
They are inverter compressor meaning you can oversize with no Ill effect.
The most simple way to figure cooling for a grow room is 6000 watts per 1000 watts of lighting. This give you enough extra btu to cool any dehueys, fan, heat load of the room etc.
I have installed several mini splits going off this formula and it always works, and if I had listened to people saying do the 3.41x watts I would have been undersized. If I had listened to my AC guy I would have been undersized.
The price difference in upsizing splits is usually only a couple hundred dollars and will be well worth it when you can fully control your temps instead of the AC not keeping up or barely keeping up.
Click to expand...
Did you mean 6000btuh per 1000w of light?
 
Roy O'Bannon

Roy O'Bannon

Well-Known Member
I am having no luck with my mini-split (30k btu) dehumidifying enough for flower. I have to run a stand alone to keep it around 50rh. You might be luckier idk.
 
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