When we first started living in our 5th wheel we used the onboard furnace quite a bit. In fact the first few weeks we went through 4 30L bottles of propane and the outside temperature was only 0 celsius. Once on the road another challenge of the onboard furnace became apparent - it used up our battery power at a phenomenal rate. We have a strange battery set up where we have a small marine battery for lighting and water pump and furnace while the larger deep cycle batteries just power and inverter to give us 110V when we are boondocking. Our first night at Oak Flats it got cold out the furnace was on and we ran out of battery at 4 in the morning. Major side effect is that the fridge shuts off! When I did a bit of investigating I found that the exhaust from the furnace waas red hot. Just put your hand close to the outlet outside when the furnace is on and you will see what I mean. This means that the furnace is very inefficient and a lot of the heat we are generating is just being vented straight to the outdoors.

We soon decided we needed a better solution and the one we chose is the Mr Heater Big Buddy imdoor propane heater. This unit can be adjusted from 4000BTU to 18,000BTU and can keep thee 5th wheel warm no matter what. It uses less propane since all the heat is released inside the trailer and it doesnt drain the battery. We havent bothered to hook up the internal fan since it hasnt been needed. We keep the vent in the bathroom open to provide a source of fresh air and havent noticed any bad effects from using the heater and our CO ,monitor hasnt beeped once. The heater does seem to have a low pressure intake as well as connectors for a 1Ib or 20lb bottle. We currenlty use the 20lb bottle with an adapter hose but might look into plumbing in a quick connect fitting from the main trailer propane supply. Thoroughly recommend this unit.mr heater