I built a spreadsheet to size the mini split for my 30×50 shop, and it ended up listing every common way to cool or heat a garage or shop. Then it hit me that half of those names don’t mean much if you’ve never seen one. What’s a PTAC? What does an infrared tube heater even look like?

So here’s a real example of each one. These are the ones I’d look at first: popular, well reviewed, and on the efficient side. Get the size right before you shop. Bigger isn’t better. An oversized A/C cools fast, shuts off before it pulls the water out of the air, and leaves you cold and clammy.

Heads up: the Amazon links below are affiliate links. As an Amazon Associate I earn from qualifying purchases. You pay the same price either way.

Window unit

The cheap way in, and what I’ve run in my shop for three years: a used 10,000 BTU unit I got for $100 off Facebook Marketplace (here is how that went). They’re loud, they only cool, and you give up the window.

• Small garage: Midea U inverter window unit. 8,000, 10,000 or 12,000 BTU on a regular 115V outlet. Quiet for a window unit, and the U shape means you can still open the window.
• Shop size: LG 18,000 BTU Dual Inverter. Needs a 230V circuit. If you need 24,000 BTU, look at the Frigidaire 24,000 BTU on a 230V 20A circuit.

Hotel style (PTAC)

PTAC stands for Packaged Terminal Air Conditioner (or maybe it stands for Profoundly Traumatizing Air Clobberer?). It’s the box under the window in nearly every hotel room. One box heats and cools, and it slides into a sleeve that goes through your wall. The hole is 42 x 16 inches (HUGE), so plan for that.

• Example: Amana 15,000 BTU PTAC (PTH153J35AXXX). Heat pump with a 3.5 kW backup heat strip, 230V on a 20A plug. There’s a 12,000 BTU version too. You also need the wall sleeve and an outside grille, sold separately.

Portable A/C

I’d skip it. Literally a fart in the wind 💨. A one-hose portable blows your cooled air outside and pulls hot air back in through every crack in the building, and the BTU on the box is optimistic. If you have to have one, get one with two hoses or a hose-in-hose design.

• Example: Midea Duo 14,000 BTU. Hose-in-hose, inverter, and it heats too. 115V.

Mini split, DIY kit

Same idea as a pro-installed mini split, but the line set comes pre-charged and screws together. No vacuum pump and no license.

BUT, I found that these were much more expensive than the non-DIY machines below (the MR. Cool was roughly 2x the price of the Senville I bought). Therefore I decided to roll the dice on a non-DIY unit and solicit my neighbor to help me pressure test because he had a nitrogen tank to pressure test, then he helped me vacuum it down.

• Example: MrCool DIY 5th Gen, 24,000 BTU. 22.7 SEER2, 230V. It comes in 9,000 and 12,000 BTU on 115V and up to 36,000 on 230V. The catch: the line lengths are fixed, and warranty claims are on you.

Mini split, pro installed

This is what I bought for my shop. I’ve heard a lot better things about the Aura than the Leto. A tech flares the lines, pulls a vacuum and pressure tests it, and the warranty wants a licensed tech to do it.

If you live in an area where it gets cold, do some extra research on the heating ratings for these. Mitsubishi calls it ‘hyper heat’, in Senville language it is getting the Aura over the Leto. Do your research before you buy.

• Example: Senville AURA 24,000 BTU (SENA-24HF). 21 SEER2, and Senville says it keeps heating down to -22°F. 230V. It also comes in 9,000, 12,000 and 18,000 BTU.

Central A/C or ducted heat pump

Makes sense for a bigger shop, or one with an office or a bathroom. You need ductwork, and that’s where the money goes. This is like a house unit.

• Example: MrCool VersaPro 2nd Gen, 2 ton. Ducted heat pump, 18.1 SEER2, comes in 2 to 5 ton. The Amazon listing includes a pre-charged line set.

Gas or propane unit heater

Hangs from the ceiling and puts out a lot of heat for the money. It needs a gas line and a vent, and the heat piles up at the ceiling unless you move some air around. They can be loud and as far as I know are on/off, no quiet kinda on mode.

• Example: Mr. Heater Big Maxx 50,000 BTU (MHU50NG). Natural gas, and it comes with a propane conversion kit. Also 80,000 and 125,000 BTU.
• Step up: Modine Hot Dawg HD45. Quieter, a little more efficient, power vented. Costs more.

Electric unit heater

Cheap and simple: no gas, no vent. The bigger ones need a big breaker, and can generate a big electricity bill. My suggestion: get a ‘dumb’ unit without a screen, you want on on/off switch and manual thermostat if you can find it. The big issue with mine is that if there is a power outage, when the power comes back, it defaults to off (not good in the winter if you have things that can’t freeze in your shop).

• Example: Fahrenheat FUH54. 5,000 watts (about 17,000 BTU), 240V, hardwired on a 30A breaker. There’s a 7,500 watt version too (FUH724).

Infrared tube heater

It heats you, the floor and the car instead of the air, so opening the big door doesn’t wipe it out. It needs mounting height and clearance, plus a gas line and a vent.

Feels great, throw on a speedo, grab a Mai Tai, close your eyes, and pretend you are on the beach. I don’t have one of these though. My neighbor installed some electric infrared heaters in his shop but mentioned to me the other day that with the 24k mini split he has, he never needed to turn them on.

• Example: SunStar SIR45-15. 45,000 BTU natural gas with a 15 ft U-tube, and it needs at least 8 ft of mounting height. Here’s the propane version.

Radiant floor

The best heat there is for a shop, and the one you have to plan before the concrete. Tubing goes in the slab and a boiler heats the water. I put 2 inches of XPS foam under my slab so I can do this someday. Get somebody who’s done it to lay out the loops.

WARNING: I learned the hard way, if you do this, you WILL have to also hire a pumper truck to pump the concrete in because they can’t drive heavy concrete trucks over your insulation and piping.

Also, I went through all that work plumbing my slab for radiant heat… I have never hooked it up or turned it on. Turns out that if you keep the shop at a decent temp throughout the winter, then the slab is ALSO that temperature. I just kept my shop decently warm and the slab was decently warm also. I live in KC though and the weather is quite unpredictable, if you live in North Dakota though, you are working on a whole different playing field.

• Tubing: SharkBite 1/2 in. x 1,000 ft oxygen-barrier PEX.
• Boiler: Argo 12 kW electric boiler. It needs a 70A breaker, so check your panel first. There’s a 6 kW one too.

Swamp cooler

Pennies to run, and real cooling where the air is dry. It works by adding moisture, so it’s useless when it’s humid, which is most summer days here in Kansas City. They work best under about 50% humidity.

I get plenty of humidity here in KC, I’m not pumping more humidity into the air, it is a pass for me on this.

• Example: Hessaire MC37M. 3,100 cfm, rated for about 950 sq ft, 115V.

Dehumidifier

In a humid place, this is what keeps the tools from rusting and the slab from sweating. Yup, but not needed if you are running A/C because it should take the humidity out if properly sized.

• Example: Midea Cube 50 pint with a pump, so you can run a hose to a drain. It only runs between 41 and 95°F, so it won’t help in an unheated shop in winter.

Get the size first

All of these come in sizes, and the size matters more than the brand. I built a spreadsheet that figures it out from your insulation, doors, windows, how often the big door goes up and your county’s weather: the Shop A/C & Heat Calculator. For my shop it came out to about 24,600 BTU of cooling, right in line with the 24k Aura I bought.