Still- We bought the 40D forced air furnace and installed it ourselves. I can't tell you about fuel consumption other than to say it's very little. The first winter after I installed it the boat was out of the marina with no shore power because of low tides and as luck would have it we got a bitter cold Nor'easter for 4-5 days during which I ran the furnace non-stop at a fairly high setting. I kept looking at the sight glass on the fuel tank the furnace draws out of and I could never see any discernible change ( 95 US gal cap.). The furnace kept the boat at about 55F while the outside temp was in the teens with a 30+ knot wind blowing.
The amp draw varies with the temp/fan setting. I'll be at the boat today and should be able to get some accurate readings since it's doubtful that the solar panels are going to be contributing anything today (Pineapple express = monsoon rain and dark). I'll post the readings I get.
SV Laurie Anne
1988 Brewer 40 Pilothouse