I’ll second this. If anything, insulate the ceiling. The summers will stay a bit cooler as well.
I’m fairly confident you could keep your garage warm with the one I have. I bought it off of amazon over 5 years ago and it’s still kicking. Fahrenheat FUH54 240-volt Garage Heater, 2500-5000-watt https://www.amazon.com/dp/B0000AXEZV/ref=cm_sw_r_cp_api_i_gNojCbYVMZADY
There’s a ton of them out there though. Just search ceiling mounted electric heater and you’ll have all sorts of options. Better than messing with propane....
Product name: Fahrenheat FUH Electric Heater for Garage, Factory, Basement, Warehouse, and Outdoor Use, Beige
Features:
Highest price ever: $418.46
Lowest price ever: $210.60
Average price: $304.34
Previous price: $309.45
Current price: $176.86
Last price change: -43%
Price change from average: -41%
Price change from all-time low: +17%
The item was in stock as of 08/04/2021 17:09:56 (UTC)
I went with the Fahrenheat FUH54 240-volt Garage Heater from Amazon:
LGs are probably fine units but I'm pretty sure will be much less efficient when the outdoor temperature is freezing or below. How long it would take for the cost of less efficiency to be equal to the extra upfront cost of the Fujitsu I have no idea. Also inefficient but much cheaper is https://smile.amazon.com/dp/B0000AXEZV/ref=cm_sw_r_em_apa_i_0YEODb03NEGA8 Which is what the previous owners of my house installed.
Be aware also that most thermostats can't be set below 50 degrees or 45 degrees meaning that you may have to heat the garage up to that temperature to prevent it from freezing (which water a lot of energy). The one in in my garage doesn't go down below about 50 so I only use it to heat the garage when I'm going to be working there, not for freezing protection. It can be difficult to determine from a listing how low you can set the thermostat.
What I do in my garage: * Use a basic 110 volt resistance heater with thermostat set to 36 degrees. That is sufficient to keep my garage from freezing when it is -20C outside. The one I use is a Dyson because it was cheap on woot (and just lying around the house) but you can probably find something cheap on Amazon for this... Just make sure you can set the thermostat low. * Use the 240volt heater (the Amazon link above) when I'm going to be working in the garage for an extended period. * For heating the car before leaving in the morning I have the most efficient option... We drive electric vehicles so we preheat the cars from my phone before we leave, so we don't have to heat the garage for this. I don't mind spending 5 seconds walking through a cool garage to my car. It is the most efficient because it saves $1000s in gas each year. You can get a decent used 7 seat Tesla for $30k, it a new 5 seat Tesla for $40k or so.