I'm in the process of building a shop that is 18x35x9. It will be insulated with open cell spray foam insulation.
I'm trying to figure out how much power I'll need for the ac/heater.

Cost is a factor, and I don't need to be 70 degrees when it's 105 or 25. Just bearable.

Is there a window unit that would cool this space? I'd love to do a mini split system but can't afford that. The ac is more important than the heat, bc I can always use space heaters if I have to.

I see some window units that claim to cool/heat rooms up to 700 sf that use 115v power. Others are 230. Will the 115 actually cool it?

If I choose the larger, I assume a 30a dedicated breaker will suffice?

That should be plenty, I just installed an LG 9000 btu mini split that runs on a 15 amp breaker for a 380 sq ft space, 8 ft ceiling with 4 2/0 windows and a 68 door.

Are you saying I should go with a 30 amp breaker and get one with 230v?

If a 115 will work, I'd prefer that because power and amperage is a little limited in the shop (100 amp)

I would always go with 230-volt if possible. It'll draw half the amperage of 120 volt system.

Really? I'm not really knowledgeable on electricity. So the 230v will use less amperage than the 115 relatively speaking?

Yes. The calculation is wattage equals volts times amps. So for the same wattage system voltage and amperage are inversely proportional

Interesting. Thanks for the info. I'll definitely look for the 230v models.

Will a window unit actually cool off the area it claims to?

I think one that is sized properly will do a decent job. The problem is to seal around a window unit, just because of the design, is awfully hard. And the window unit won't provide heating. I bought mine including the line sets for under $1,000

Some of these window units have heaters with them, it not sure if they are effective. It's not going to go in a window, I'm going to pick a unit and frame an opening in the wall to fit it. Sealing will still probably be a pain.

Some of the split systems are around $1000 and if I get into that ball park I may look at those. I was hoping to stay around $600

That's the same math I was working with. But those window units are generally so poorly built that they might last three years. The LG system I bought has A 5 year warranty. And it's so quiet you can barely tell that it's running.

Big ass fan and one of the 20k btu kerosene heaters?

I'll have plenty of air circulation. I'm wanting some cooling in there as well.