The short answer is that the Alde heater draws just over 1 A for basic functions/operation of the heater.
A more detailed answer follows below. There are two functions in the Alde Compact 3000/3010/3020 that draw >0.1 A of current from the vehicle’s 12-volt battery. The combustion fan that supplies air to the burner (≈ 0.4 A), and the circulation pump that circulates the hot glycol fluid in the heating system (≈ 0.2 A).
So normally the heating system draws ≈ 0-0.6 A in LPG operation and ≈ 0-0.2 A with 230 V electric cartridge.
At maximum, the heater draws 1 A for about three seconds when starting at 12 V DC. In 230 V immersion heater operation it draws ≈ 4.5 A on 1 (1 kW), ≈ 9 A on 2 (2.1 kW) and ≈ 14 A on 3 (3.2 kW).