How do you get air out of a hot water home heating system?
The hot water is brought through a series of small tubes like a radiator in a car by means of a circulator pump that pushes it. A small blower fan blows air over these coils filled with very hot water, extracting heat as the air moves over them, the now lukewarm water is returned to the water heater through a oneway valve where it is reheated and the cycle continues.