I was talking about the finished garage in general.
Does the furnace have a min temp? I guess those units don't. I know when I put the house furnace in garage of the old house it said in the manual to keep it above 55.
It's just a gas heater... I guess I had just assumed there wouldn't be any issues with a low temperature, but now that you mention it I did find this from another manual:
"Unit heaters should not be installed to maintain low
temperatures and/or freeze protection of buildings.
A minimum of 50°F (10°C) thermostat setting must
be maintained. If unit heaters are operated to maintain
lower than 50°F (10°C), hot flue gases are cooled
inside the heat exchanger to a point where water
vapor (a fl ue gas by-product) condenses onto the heat
exchanger walls. The result is a mildly corrosive acid that
prematurely corrodes the aluminized heat exchanger and
can actually drip water down from the unit heater onto
fl oor surface. Additional unit heaters should be installed
if a minimum 50°F (10°C) thermostat setting cannot be
maintained."
I'll double check what the Mr. Heater manual says...
The nest has 'safety temp' settings that allows the heater to turn on even if you have it set to off so you don't end up with pipes freezing, but obviously I have no pipes currently. Maybe someday. Sounds like I might need to bump this up to prevent condensation on the heat exchanger