Now I know.
I wouldn't have thought thats it would have warmed much without some sort of a pump to circulate? Obvioulsy you can't use the engine circulator (water pump).
This is an obvious word misconception the water pump doesn't pump anything is just assists with circulation.
The coolant in the cooling system is heated and circulates via convection currents within the cooling system.
I just unplugged my TDI wagon about an hour ago and drove home, and can clearly say that plugging in does not give instant heat. It does ease starting (the glow plugs stay on for far less time), and it does begin to warm up sooner, but that's it. With the cold weather a bigger foe is driving with all that air rushing through the radiator and intercooler. I'm working on getting a set of winter front plates (black powdercoated stainless steel) cut at my local lasercutters....but just haven't got that nailed due to lack of time at the moment.
As far as the pump goes...there are two families of pumps: positive and non-positive displacement pumps.
Positive displacement pumps include piston pumps, gear pumps, vane pumps and all of their subdivisions (variable displacement piston pumps, vane pumps, bent axis piston pumps, etc, etc). They displace a specific amount based on their volume per revolution.
Non-positive displacement pumps (including centrifugal pumps) do not displace a given amount of fluid per revolution, but are still pumps. Turbochargers and centrifugal superchargers also fit into this family. The benefits of this type of pump are primarily that a blockage on the outlet does not hydraulic the pump, and a restriction on the inlet of a non-positive displacement pump will have less cavitation (an implosion caused by very low pressure (as in drawing a vacuum)...which results in pitting and eventual failure) than on a positive displacement pump.
