The heater, and its little muffler in the wheel well, can collect unburned fuel during failed starts, then produce alarming clouds of smoke for a minute or two during the next successful heater startup. Allowing the unit to reach operating temperature takes about five minutes, and after a few cycles should start up with only a quick puff of smoke.
Here’s my van’s cheat sheet on how to program the 7-day timer, if you’ve got one. It’s on the center console by the shift lever... otherwise you’ll just have a coin box, though you could also have the optional wavy-line “aux heater” button among your switches that runs the furnace in aux heater mode when parked.
The Espar itself is a small diesel furnace that heats the engine coolant. When operated with the engine running it reduces warmup times (“boost heater” mode) or with the optional timer/button can also run when parked, key off (“aux heater” mode).
Espar units REALLY like being run periodically to keep their parts moving (fuel pump, combustion fan, glow plug, and temperature sensors). Running it for 15 minutes at least once a month will help extend its working life.
-dave