Wow, looks like there are lots of these using Espar's design nowadays. I went with a Planar, which is, if my research is right, a Russian knockoff of a Canadian built marine furnace. I have not installed yet but the quality looks good, especially for the $500 I paid. I figure the Russians know a thing or two about heat.
I went with the Wallas Nordic DT diesel-burning, marine combination cookstove and heater. It's significantly more money than an airtronic knockoff, but wow--I really love it. It was definitely the right choice for my use case.
Anyone running a hydronic d5? I'm thinking this might kill 2 birds with one stone and act as my block heater being I live in ND but was wondering what the drawbacks would be? I have a passenger van and can just tie into those coolant lines in the back. Would I need a heat exchanger or can I just supply power to the van heater in rear from house battery?