For those withe newer FWC with heat - the Honeywell digital thermostat the are now using (TH1100DV) can be configured to allow temperatures down to 35F. This is useful for those who want to leave their furnace on at a low setting to prevent things from freezing without wasting too much propane. The details on how to enable this lower temperature range are available here:
In short, press and hold both the up and down buttons until the thermostat displays 5 5. Press both buttons again and it will display 14 0 (you can press the up arrow to change this to 14 1 which will display in celsius). Press both buttons for a third time to display 25 0. Press the up arrow to change this to 25 1. Press both buttons to exit the programming mode. The thermostat will now allow set points down to 35F/ 1.5C.
I think this has been covered before on WtW (probably where FWC got the idea to update the thermostat!), but I wanted to make it clear that the current heater comes with a thermostat that is capable of 'garage mode' and you don't need to replace the thermostat to get this functionality.