What does a heat engine converts heat into?
A heat pump works by means of a reversing valve. When you want
air conditioning, the valve reverses and pulls the hot air from the
home, through the compressor and coils and deposits the hot air
outside of the home. When you want heat (provided the outside temp.
is high enough to contain heat,) the valve reverses and pull the
outside air through the compressor and coil into the house. This is
all possible because of a very low boiling point liquid in the
lines.