How much diesel does a diesel heater use?

There is no single fixed answer to how much diesel a diesel heater uses. Consumption depends on the model, heat output, and how hard the heater is working. Therefore, I use the manufacturer's figures as a starting point and calculate from there.

Specific figures from AUTOTERM

For the AIR 2D, AUTOTERM states approximately 0.10–0.24 liters per hour, and for the AIR 4D, approximately 0.12–0.51 liters per hour. The AIR 9D is higher, at approximately 0.42–1.0 liters per hour. These figures clearly show why it does not make sense to use one standard number for all heaters.

Why does reality not always match the table values?

A heater rarely operates at the same power level all the time. When the boat is cold, the heater may run at a high level. Once the temperature is reached, it can regulate down. Insulation, outside temperature, air distribution, open hatches, and the desired room temperature therefore affect the total operating time and the actual daily consumption.

A simple calculation example

If your heater averages around 0.20 liters per hour and runs for 8 hours, the consumption is approximately 1.6 liters. This is a calculation example – not a guarantee of consumption for a specific model.

Tank size: plan for a reserve

I prefer to size according to realistic usage rather than an optimistic minimum figure. Take the expected average consumption × number of hours × number of days and add a practical reserve on top. Also, remember that the fuel line, filter, and pump must be installed according to the heater's manual.

See fuel parts for diesel heaters · Read about diesel, HVO100, and GTL