Heating garage

Sorry I don’t know in Canada, though typically Canada is MORE strict on a lot of codes.
Here in kansas it is not allowed to connect the HVAC to the house because of concerns that you would run fire up a car, and the CO and CO2 would enter the house, and kill you in the basement.

Obviously one can ensure that won’t happen but no code inspector would give it a thumbs up, and it would have to be taken out if you wanted to sell the house.

I would go the space heater route, unless you really want to keep the garage heated all the time.
My shop is a third stall of the garage. I have a electric heater in it (for dust) but it has a thermostat, so I can just turn it down and leave the door between the 2 car and 1 car side open to keep the place ‘warmish’ then when I work in the shop I close the door and turn the heat up.
I use this 5000W unit 17000BTU
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_595_595

When I bought it 3 years ago I paid $219 but there is no exposed heating element, so I never had to worry about fire from sawdust.

-- "_If we did all the things we are capable of doing, we would literally astonish ourselves_." Edison

One word; kerosene.

I bought one for my two car garage similar to Dave’s. It’s 5000 watt 240volt 30 amp. It’s made by Cadet it’s called the HOT ONE. Ive had it about a week and it works great, although we don’t have the temps like you did. I was able to get the garage to heat up from 30 deg f to 60 deg f in about 25 minutes. My garage is 400 sq ft. with an 8’ 6” ceiling. I paid $225.00 U.S. they make two versions under the same name one is 4000 watt and the bigger is 5000 watt. Get the bigger one if you’ve got the circuit for it.

http://www.cadetco.com/show_product.php?prodid=1012

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Even at -8 you don’t really need to heat the garage for the car as -8 or +8 doesn’t really make that much difference to the longevity of the car. If you are storing paint or whatever that is a different question. I use a 4800 watt electric ( on a 240 volt circuit) when I want to work in my shop which is the none car part of my 2 car garage. It was coolish here the other day (mid -20s C) and I had the shop up to 18 degrees in a couple of hours, I actually had to turn the heat down as I was planing some drawer sides and was getting too warm.

As mentioned, in earlier posts, I don’t think it would be wise to give CO a chance to leak down into the living quarters, and these electric heaters are inexpensive to run.

-- "Checking for square? what madness is this! The cabinet is square because I will it to be so!" Jeremy Greiner LJ Topic#20953 2011 Feb 2

I use natural gas

-- W James Brokenbourgh Custom furniture maker http://artisticwoodstudio.com/

Is it possible to just install designer radiators in the garage? I wonder if that will be an affordable option for you. I do not know of any other ways to help you though.

-- http://www.radiatorshowroom.co.uk