Sizing a Mini-split air conditioner, your experience?

[biggerbud]

Hey guys -- I spent the last summer letting the poor old house AC attempt to keep the basement cool. That AC was running all night long trying to keep the basement room cool. So I'm thinking it's time for a mini-split. It HAS to be more efficient than the 30 year old AC running

Setup:

around 4K of lights, cool tubes vented to attic. 1 room and a tent for flowering (three 1K lights). 1 tent for veg (600Watts)

house AC available for extra push on worst days/nights.

I'm leaning toward the Freidrich 12K BTU breeze. But for 400 more I can get the 24K unit. Do you think 12K is sufficient for 4KW in a basement? Another advantage of the 12K unit is I have the power already available. I will have to run a 240 line for the bigger one (not a big deal, but more work).

thoughts?

 

[Neiko]

1 Watt = 3.412 BTU....So 4000 x 3.412 = 13,648 BTU's. Most ductless split air conditioners have inverter drive compressors, this means that the compressor has the ability to ramp up or down based on the environmental conditions. If the unit you are looking at has an inverter compressor I would go for the 24,000 BTU unit and it will "size itself". If it is not inverter driven, I would look for a 15,000 BTU unit. The more oversized the air conditioner is, the poorer your dehumidification will be and you will short cycle the unit which leads to premature failure. Longer run times gives you much better control of humidity without over cooling the space.

 

[biggerbud]

thanks!

Since a significant part of that BTU energy is being vented, would that change your opinion? It seems like at least half the the HPS heat is being actively vented out of the room (no data about that, but clearly the fans are actively removing a lot of the light heat).

 

[Neiko]

If the heat is being vented completely out of the room and not just out of the tent (into the same room) then the 12,000 BTU unit would be fine.

 

[biggerbud]

yes, I have four 6 inch ducts (one for each light) leaving the room into the attic.

 

[Dutty Panty]

Heres my setup hope it helps only flower room has mini split I have 2 head units in flower room.

(10) 600 watt hortilux hps bulbs
(5) lumatek dual 600 ballasts
Room is climate contoller by
Mitsubishi 3.5 ton multi zone mini split was about 6000 installed
My pre flower veg room I just pull cooled air from beneath the canopy through a can fan then up a sealed shaft between 2 studs to a floor register on the upper wall in pre flower my other veg is just using the homes heat pump.

So basically for 3000 watts I'd say get 1.5 ton unit if possible
Each one of my head units is 18000 btu I believe

Heres some pics I'll take outside pics of the heat pump.
I know 6000$ is alot but I've saved that in electricity a Window ac unit or a cheap mini split will pull about 15 amps my mitsubishi is pulse generating so only draws half an amp so.5.
I'm saving about 100 a month in electricity now 2 Window units at 12000 btu just couldn't keep up.

 

[Dutty Panty]

I've given up on the picture rotating problem Damn phone.

 

[Dutty Panty]

 

[Dutty Panty]

There's one of the 2 head units. It has improved yield and quality significantly. 1/4 of first harvest with it paid for itself

 

[Dutty Panty]

You can't see but thats half the room. To the left is more behind that door and the other unit is over there.

 

[biggerbud]

thanks for the info!

Are you worried about the noticeable power draw? I've thought about bumping to 6K of lights but I want to stay under the radar.

 

[Dutty Panty]

It does add to the cost. About 300$ per month to run electricity, including ac, co2 as well

 

[JerryAllen]

To determine the BTU requirements for your room, you first need to know the size of the room and the heat load that it carries before adding any equipment. Many people base their final calculation simply off the number of lights, however the room size, presence of ballasts, dehumidifiers, and other equipment will also have a significant effect on which unit to use. Factors like high ceilings, poor insulation, and excessively high ambient temperatures can also drastically affect the BTU requirements. Use the sizing chart below

This chart can be used to help determine the necessary cooling requirements needed for your grow room environments.