Air Conditioning Question

I am currently looking at a grant from Home Depot. (Up to $5000 in gift cards)

I need a project for the grant. I was considering maybe AC for the classroom. I need someone who knows AC better than me to tell me if that is even a good idea.

The thought was maybe to get a 48,000 BTU mini-split AC. ($4,200+)

Classroom is about 636 sq. ft. (about 20x29 plus some nooks).
It is poorly insulated (brick wall on inside is the same brick wall on the outside)
It has a single window and 2 double doors and a single door.
It has a drop ceiling. I think it is the normal 10ft height, but I need to check.

The BTU calculators on the web are all over the place for this… so I need some expert help.

1.) Is adding a mini-split a good idea or a bad one?
2.) What would be the correct size if it is a good idea?
3.) What else would be a good purchase from Home Depot if this is a bad idea?


48000 BTU is probably oversized. It probably won’t matter though. Most minisplits, but not all, are inverter drive and can modulate their output to track the load. Having it large like that lets you recover from a temperature setback quickly and then run at reduced capacity to manage humidity and the live load.

If you really want to calculate the load correctly, do an ACCA Manual J. I have a copy if someone is interested.

As a side note, I have some classrooms in my building that can’t get cool on a 24000 BTU window unit, they are similar construction and size but have the benefit of another unit on top so no solar gain via the roof. They also don’t have 30 sweaty makers in them at one time. I’d say go for the 48k unit and feel good about it.

I would go for a minisplit vs any other type of AC since they are very easy to install, efficient, and don’t require ductwork. Bonus: any decent mini-split also doubles as a heat pump for winter use.

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Just remember when we move, the A/C stays

I know… give me some other options… the seem most interested in education…and veterans… so probably something for

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Portable AC wouldn’t have to stay.

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Hmmmm… portable ac goes up to 14,000 BTU… that is about 700 sq ft. Classroom is between 600 and 650 sq ft. Does anyone know if the height of the ceilings is 10ft?

I am a little leary. Most of the places I’ve seen portables, they are way underpowered.

(Of course I have no idea if the folks putting them in have a clue.)

Any thoughts from the crowd?

Window or through wall from Lowes. Heat and cool and would not stay with the building. With the landlords permission it could go through the wall were there used to be a door. Would require running 230 volts to there, but any solution to the air conditioning problem will require running power wiring.

Mike B

I have a concept that will reduce AC electrical requirements by 50%. We need a prototype design and build. Is this the type of project you are looking at for your grant?

Wasn’t what I was looking for here, but we could look for a grant that might fit that. Is this something you want to get a patent on and make money from? (That will make a difference where to look for money)

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On of the Speakers at NOMCON is working at MIT on a similar endeavor. I have his email if you would like to chat.

Yes it does.

It doesn’t have to be for profit. How can we meet?

I will be at the space on Saturday after our Breakfast with the board. Or you can just email me (its my first name at