If you are going to be using your rig in cold weather, there are a few things you can do to make the furnace run more efficiently. Make sure you have the proper voltage and LP pressure. Ensure that all your vents and cold air returns are open and unobstructed. Insulation can be added to areas such as the windows. Add quilted blankets or pads to the front windshield area and supplement the furnace with a catalytic heater.