The heat pump is significantly more energy efficient than electric resistance heating. Reducing unwanted heating or cooling energy input. It provided ventilation before forced air heating and cooling. A Stirling engine can function in reverse as a heat pump for heating or cooling. Heat exchanging coils for the steam heating of hydrochloric acid are made from tantalum. This is also called combined heat and power district heating. This is much more of a problem with cooling systems than heating systems. Its heating and cooling must be rapid. Its heating and cooling must be reversible. All physical systems are capable of heating or cooling others. Its heating and cooling must be monotonic. No. 1, which tends to become brittle with prolonged heating and cooling. Cast iron stoves for heating and cooking displaced inefficient fireplaces. Several methods of electric space heating are used. They introduced the contemporary services of central heating and electricity.