What Is a Diesel Heater (Webasto Type)?
A compact diesel stove that heats the cabins with very little fuel — a device that extends the season and, when run on a low tick-over, quickly rewards itself with soot.
A diesel heater, commonly known as a Webasto or Eberspächer type, burns fuel taken from the boat’s own diesel supply in a small combustion chamber and blows the heat into the cabins, or circulates it through a central-heating circuit. It carries you from October into December, and from March into the season: with fuel consumption measured in cupfuls per hour, it keeps the whole boat dry and warm.
Its nature is much the same as its diesel cousins: it likes to work under load. If it is constantly run on the lowest setting, soot builds up in the combustion chamber and it falls into the classic habit of blowing white smoke and shutting down in protest.
The survival recipe
Start at full power: for the first run of the season, do not just give it a brief test — run it at full power for half an hour.
Do not switch off before it has warmed through: shut it down only so it can complete its own cooling cycle.
Fuel filter: fitting a separate fine filter can prevent faults caused by dirty fuel from the tank bottom.
Voltage sensitivity matters too: starting the unit with a weak battery will trigger ignition faults, and many so-called heater problems are actually battery problems. Smell of exhaust inside the cabin is never normal; the exhaust insulation and the hull-side outlet seal should be checked every year.