Diesel parking heater. I love these things, about the size of a loaf of bread. Exhaust pipe, combustion air intake, and fuel lines are plumbed out the bottom of the unit. They make very dry comfortable heat and are extremely efficient. Need 12V to run the fan, pump, and glow plug.
Fuel pump is external, try and locate it as far away from where you sleep as possible! It makes a tick tick tick noise as it runs. Housing is rubber, but I like to also hang it from zip ties for even more vibration insulating. I have mine up by the engine compartment and I cannot hear it at all from inside the camper.
