Propane vs Diesel Furnace

[coyotearms]

This is my first post! I know there are threads about propane heat and other threads about diesel heat, but I could not find something on pros and cons of each. Since I have a diesel E350 cargo van ready for conversion, I initially thought, hey, it's diesel, so let's go with diesel for hot water and furnace. It seems that a whole lot of folks go that route. But I am not sure anymore. While it might seem convenient to have a one-fuel RV, I started thinking that whatever propane you use, especially for heating, you don't use diesel, and therefore you have greater range. You also don't have to worry about not having enough diesel to get back to civilization after than nice cozy evening over wine and chocolates.

A rough calculation based on SMB website for their 12,000 BTU heater (57 hrs per the 7.9 gal tank) and the Espar D4 manual at the same heat output burns 0.116 gal/hr giving 68 hrs. Thus to get the same power level for 57 hrs. cost 6.6 gal or about 100 mi. of range. This calculation implies the propane furnace is more efficient that the Espar since the energy content in propane (91,500 BTU/gal) is only 66% of that for diesel (139,200 BTU/gal), which should have resulted in the Espar going for 86 hrs. instead of 68 hrs. on 7.9 gal if both furnaces were equal efficiency.

Now consider the economics of the initial investment. You can get the propane tank, furnace and stove (which gets you hot water) for over $1000 less than just the Espar Airtonic D4 heater. It gets even more dramatic if you compare the propane path with the Espar path that includes the flat plate water heater; this combo is over $1000 more. If you don't want to run the engine to get how water (at about 2 gal/hr idling the diesel) by getting the Espar Hydronic the total difference between the propane route and the diesel route is around $3500! And it appears the diesel appliances would take more maintenance to keep working well.

So what is the deal? Maybe it's weight, but that difference is probably only the weight of the propane tank. And that 8 gal. tank does nicely squeeze under the vehicle without compromising clearance.

Maybe it's space in the van. Although I do not know yet where the propane furnace usually goes or how big it is (some help here would be appreciated), I have done a bit of research on the Propex heater, that I has seen mentioned somewhere on this forum. It is only a little larger than the Espar Airtronics D4, and it should install very similarly in that it has ducting for combustion through the floor and uses a flexible duct to deliver hot air to the living space. It's output is about 10,000 BTU/hr, which is the same as the Espar at its high setting (although the latter also has a "boost" setting of 13,650 BTU/hr). The Propex also draws about the same current of 1.9 amps. For details on the Propex see
http://www.westyventures.com/propex.html.

So unless there are compelling arguments that I have not considered, I cannot see why one would go with diesel devices for air and water heat. Please help me straighten out any twisted logic.

I should mention that the 110v electric water heater option (apparently an Insinkerator W152, that can easily be used in preparation for stopping to camp while you are driving if you have an inverter does not seem like a bad option either (the 2.5 gal tank typically goes under the sink). With it if you get decadent and camp with a 110v hookup you have continuous hot water. Add a little ceramic space heater and hot plate, and your good to go for as long as you like---can't do that so easily with a diesel furnace. Comments?