... made that mistake once when I forgot and parked next to Sean at the Caverns ...
How much from scratch??
Lenny, installed the 675-d 240 volts for 5 zones with engine pre heat in his H-45 everything he was at 15,483.00,they draw 13 amp + on DC depending on what size exchangers. Bob AquaHot has always been straight forward about the fuel usage how these guys burn less I have no idea but I can tell you if I spend big bucks for a unit I am going to stay warm Ours would use 5 gals + a day at freezing temps in a well insulated coach then we had generator time check out the Aquahot site they love to use these little things when it come to fuel usage * for cold weather ** for extreme cold weather lol Owning one I don't buy into the low fuel usage because we have used FlowScans on the things before to check the fuel usage and know exactly how much fuel one will use in freezing weather to keep a bus @ 72 degrees. You don't have to be married to AquaHot there are other brands on the market just as good if not better than AquaHot fwiw or build your own good luck