Can be done for far less:
I added an 'infrared' gas heater, hung from an upper wall, to my garage (also my workshop).
It has no other heat source.
The heater was under $250, and installation (gas line also runs thru garage, so was 'easy') maybe another couple hundred?
It does use a pilot light, but I only turn it on when I'm working on something for a while in there in winter.
Placed the t-stat near by, but around a corner.
Amazon.com: Mr. Heater
(Wow, that has really gone up in price!)
It works
really well - in fact far better than I'd expected it to.
(It kept me nice and warm, for a few weeks while I was building some furniture (AV rack!) in there, and eventually (over several days) would get floor slab heated up, a bit too.)
> Use cost is neglible - even if used continuously for a few weeks, I don't recall ever seeing an increase of more than a few bucks in my gas charges.
> I mostly leave it off, and gas disconnected, and dont' mind climbing a ladder (where I store it!) to turn it on and fire up the pilot when needed, but also found it really reliable for longer runs, too. Did learn to remember to dial back the t-stat from 'roast' after a day or two, the hard way (>80deg in garage!).
(Edit: The garage is pretty air leaky, so I'm not concerned about fumes...in a really tight garage, it'd be less ideal.)
> I have several smoke/CO2/gas detectors in there, just be sure (networked, so both phone and other detectors inside would go off 'in sympathy', too).
> Aside from workshop. it's also really handy if I need to work on the truck for any reason in winter....ah, brings up another point:
> Leaving the garage unheated (ie, below zero) reduces the effect of salted streets on the truck, another reason I leave it off usually.
The truck is 20 years old and shows very little rust.... I also leave it's windows open to air out moisture inside it when parked.
> The comment about having a 'spare' heating source also played into my thinking - main home heat is a Triangle Tube super high efficiency gas boiler driving underfloor radiant (but also have baseboard electric as a backup).
This garage unit provides a heat source with no dependence on electricity (boiler has pumps) and I keep a lighter in there specifically for it.
Mostly psychological, of course.
> Garage is decently insulated but unlike the R40 in the house walls, has only 4" studs; roof/ceiling is flat with 'typical' insulation (ie, not superinsulated).
For less than about $5-600, I'm really really impressed with how much of a difference it makes when I need to work out there in winter, and just
having the option is somehow 'freeing'!
PS> I also bought a new Mitsu heatpump mini-split, mostly for AC, but it also does heat; it is not any 'more' efficent than the boiler. But adding a head unit for that in the garage would have been thousands.