Word to the curious - be aware that this mod is very labor intensive. I chose diesel for reliability and safety compared to the propane or matching heater fuel to vehicle fuel. I'm pretty sure those installations would be a lot easier. On the other hand, ....[/URL]
I've owned both Espar and Webasto diesel heaters. Diesel is certainly not more reliable than propane or gasoline. Normally an auxiliary tank would run kerosine to avoid diesel.
My concern with Propex is support in the U.S. The easiest propane furnace to fix (or get fixed) in the U.S. is the oldschool Suburban RV furnace. IMO anyone doing a build of a full time rig should consider the Suburban. The only advantage of the Propex is installation flexibility.
My current new build plan is for a gasser Transit with the big heater being the Webasto airtop gasoline unit. Backup will be a Camco 3 radiant (Because the Webasto will inevitably break). Mild nights will be electric heat off the batteries.
My previous rig was a custom Unimog with a Webasto hydronic on the engine and an airtop in the camper. Usually a wonderful way to heat. A mysterious PIA when the units would not fire up.