[RMcNeal]

Water heater was my guess too. Also, I wouldn't leave the belly open during winter. You won't have any heat down there at all. I've been in -7 degree temps for a few days and ran electric heat in the basement and inside the rig. Only used 20% of 1 30 lb tank for 2 weeks. I bought remote temp sensors on Amazon and put one in the garage, one in the basement and one outside. That way I can tell if I need to run furnace.