Auxiliary Heating

[X5-UK]

Hi folks,

Okay, Scotland can be pretty cold...we even have some ski resorts (well on a good day). So, to be able to heat up the passenger cabin of a muscular X5 before you venture out into the cold seems a good idea...right?

Now, as I understand it, the auxilary heating (operated by remote control from the comfort of your lounge [USA lounge=family room]) doesn't actually start the engine but instead starts a water-based heater which is supplied with energy from the car's fuel system. The heat is generated by burning a fuel/air mixture in a small combustion chamber, the engine coolant being heated by a built-in heat exchanger. A separate electrical water pump then circulates the coolant independently of the engine coolant pump. It operates for a maximum period of 30 minutes, and the water temperature in the small heater circuit is kept at 70-85 degrees centigrade, regardless of the heat drawn from the system.

Question:
So how the hell does it heat the passenger cabin...or does it not do that?