The best engine heater I ever had was a 1500 watt tank type heater. The hot water output of the heater went right into the head where the combustion starts in an indirect injection Diesel engine and the engine started easily.

Another advantage of a high powered heater is that it has to be left turned on for a much shorter period of time so I had a shorter wait time. It is actually more efficient because it has to be energized for a much shorter period of time. No heat is lost thru the radiator because the thermostat is closed.

I had a 220D that had the rings "cooked" by overheating I.E. low compression, and it wouldn't start cold even in the summer. That 1500 watt heater would get that engine started even in the winter.

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