90 plus furnaces are good choices for garage heat especially when they are two piped. Your compustion air is less apt to be saturated with flamable vapors and hx should not get hot enough to ignite vapors in space when installed above the classified zone.

What is the height of the large door?

Some good threads in the past on this topic:

http://www.offshoreonly.com/forums/s...archid=1564673

I talked through my experience here: http://www.offshoreonly.com/forums/a...oy-box-up.html

Big door is 12x12. Small ones are 10x10 I think

24x40 pole barn, sort of a work in progress.
http://i105.photobucket.com/albums/m...psjz6hq2mw.jpg

Found a satellite pic showing just how tight I squeezed this thing (30 x 56) on my lot. The green "tent" is a 14x42 "portable garage" that the boat used to sit in and is now holding the toyhauler for camping with the racecar.....however, that tent is not on my lot. It's actually in the field belonging to the people behind me (they let me keep it there)

Dude, you have cock and balls sidewalk in front of the house LOL

I thought the same thing!

They`re not ideal if the temp isn`t kept above freezing. The condensation freezes in the trap if I don`t fill the draft inducer with antifreeze at the of the day. 80+ is a much better choice for the average Joe.
my 4 car has plenty of make up air, I don`t like 2 piping any 90+ if I can help it.
Just today I found 3 dead mice that had made a mess of the burner box and clogged the intake plus all the nuisance calls I get when the intake freezes up.

yep, I keep mine at 55-60 all the time.... I also use condensate pump in case it freezes going outside (It did once without) so far no issues since, but I do use the intake pipe since I paint a lot, never had a mouse yet. I never did put a screen on it like I say I will. The condensate froze once before I used the pump and it was a huge cold spell, sucked to thaw garage enough to get it going again, with the pump it will at least overflow into garage floor but furnace will still run... I did not tie in cutoff for that reason like I would in a house.