Window units

You have a roll up door or just a regular walk in door? I had to get a dehumidifier due to my roll up door even though the room is insulated otherwise

I put Toshiba window unit in mine, it's setup on a timer control so it's only on for four 1.5 hour periods per day. Has no trouble keeping the humidity in check.

I’ll tell you the problem with dehumidifiers is they have a motor and it produces heat, especially the cheaper ones. I think you can buy expensive ones that don’t. Now it doesn’t seem like a lot of heat, but you put it in a small room or what ive seen is in AC return closets. Well hell now you are raising the AC return temp 5 degrees and killing your AC value.

I probably wouldn’t recommend just a dehumidifier foe a garage for that reason. I’m no AC pro though.

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I’m looking to get a window unit for a garage, shop that’s about 350 sq ft and insulated. I do not need to keep it cold, but I would like to keep it moderately dehumidified. What should I get? Do I need a separate dehumidifier? My current ac unit has no thermostat, mostly just on/off. Tia.

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You said you currently have window AC with no thermostat - does it not presently keep the garage sufficiently cool and dehumidified to your liking?

Assuming it does not, there are on-line calculators to determine the heat load of your garage and what size HVAC you need that takes into account the insulation in the wall, attic, windows, R factor of the garage door etc that will help you size an appropriate size BTU window AC. Try this one - just add the specific info for the garage. LINK

If properly sized and with thermostat, and with the garage fairly well sealed as you state, I would think it should suffice in keeping the garage at a desirable humidity - 50% and below for most of the year. Perhaps you should consider a window heat pump that will provide both cooling and heating to the garage year round, but more expensive than a straight window AC.

You can always retro insulate the garage door if required and add a dehumidifier at a later date if needed. Get one of these to monitor humidity - they are are pretty accurate and can be calibrated if needed.

Good question about the existing one. Since it’s only hi/med/low with no timer or thermostat, I’ve assumed it would probably be horribly inefficient. Maybe I should just let it run 24/7 on lo and see what happens.

Because it’s impossible to cheaply condition this space or because it’s a window unit running excessively?

So you think spending the coin on a new one with a thermostat would be worth it?

Is your garage door insulated? If not you can buy a kit off Amazon for around 100 bucks and do that first. Then I'd install a slightly larger than needed window ac that has its own thermostat. Based on your square footage in the garage, I'd get a 1.5 ton (18,000 btu) unit. Why slightly larger? Even with the new garage door, and insulating panels, you'll have leakage around it. The extra half ton will help with lowering the humidity.

Disclaimer: This setup may significantly affect your electric bill.

I have a 400 square foot MIL cottage in my shop and I put a 12,000 btu LG in it. Works great. Under $500