gpsman wrote:The car heats a tank of water, and then the hot water heats the air exchanger going to the cabin. While parked, that hot water will retain heat for quite a while.
TIP: Turn off the “heat/cool” button 5 or 6 minutes before reaching your desrination to save energy. You might as well use up that “stored” hot water, and no use parking with a hot water tank, unless you will be parked for only a few minutes.
That tank is very small, and cools down very quickly (within about 15 seconds). You're not really recovering much heat there, as much as you are just tolerating the cabin cooling down before you get to your destination.
Even on a really cold day, it should take about 2500W to maintain the cabin temperature. If you turn off the heat 5 minutes before, you're going to save about 200W of power. That's about $0.02 in electricity.