Look into a Direct vent heater, They use outside air for combustion and have a exhaust vent that also exits outside, you can use propane or natural gas for fuel.

 

This has absolutely nothing to do with nothing, but I can't stop thinking about it.....did you know that our friends across the pond pronounce "garage" similar to "carraige" but with using the "g" so it would be like garraige. Just thought I'd mention that! Lots of folks up here in VT use the old mobile home heaters and hook up to 100# tanks like mentioned above.

 

Ok peeps. Here's the story.

I used to sell heating and A/C years ago. Also, my old man owned a plumbing, heating and A/C company for years.

Anytime you add heat to cold air, condensation can occur. There is practically no good way to avoid it. If it's cold in the garage and you add a blast of hot air from any source, expect condensation to occur.

That said, I have one of these. It vents through the wall versus through the roof. It's a great heater.

There are several other companies that make a similar product. I've had excellent service from this one.

 

I like to just drench the floor with gasoline and jiffy pop. When the popping stops its time to leave.

 

The link will take you to what I use. I just move it around so it is next to me while I am working on the bikes. No problems keeping me toaty even with snow on the ground outside.

http://www.walmart.com/catalog/produ...uct_id=5142284

 

All I can say is good luck with no insulation. I have a standard old 2 car garage, I have a 25000 BTU propane heater I have used for years. It worked just OK. This last summer I invested the few dollers it took to insulate the garage and man what differance, it now always stays 20-30 degrees warmer than outside and when you fire up the space heater it takes 1/2 the time to warm it up and it stays warm 3 times as long. It also stays cooler in the hot weather. Check out insulation in the roof I got blow in insulation for $300 installed!!
With no insulation what ever you do be careful you don't gas yourself or burn up all the oxygen in the area; a lot of new houses are sealed up real tight. Stay away from kerosene that stuff is nasty.

 

I just bought a forced air "construction" style heater from Lowes for $99. This thing kicks butt. Heats my garage +20 degrees in 20 minutes. You need to keep it ventilated, but works great. Runs off a standard 20lb propane tank for 14 hours.

http://www.lowes.com/lowes/lkn?actio...50C&lpage=none

 

AHHHHHHHH!!!! Borrowed a kerosene construction heater from work, and man did that thing stink!!!! I've got a nasty headache and I can't wait to bring it back. Someone tell me the propane doesn't stink like the kerosene? Insulating the garage would take an army... there is an upstairs loft and bare walls filled with shelves and stuff... I guess I could insulate the roof rafters, but I don't think that will do it. I like the idea of propane is it going to give me a massive headache? Someone suggest a propane heater other than the one from Northern?

 

The propane heater does have "some" smell and fumes. Its not much if you keep it ventilated. I usually keep my garage door cracked an inch or two to allow for exhaust. Of course this allows some cold back in, but not much. On high, this little heater really puts out some warmth.

For $99 I don't think you can go wrong. I am extremely pleased with mine. Try it, if it doesn't work as expected, take it back.

 

natural gas heater here.