The basic principle of pre-heaters is to heat the passenger compartments and cabs of all kinds of vehicles, without having to depend on the heat given off by a running engine. Water-based pre-heaters have a compact design and can be fitted almost anywhere in the engine compartment. They are therefore the pre-heater of choice for cars with interiors too cramped for additional installations.
The heat generated by the combustion chamber is transferred to the vehicle's coolant, and an (additional) electric circulation pump distributes the heat – even when the engine is off. Then, the interior fan is activated automatically, and everything works as it does in normal heater operation. The pre-heater runs on the vehicle's fuel, straight out of the fuel tank. You can activate it at your convenience, via a timer switch, a radio remote control or a smartphone app, depending on the model.