Chillers and Heat pumps work on the same principles of vapour compression cycle. The chiller operates at 12/7 deg C(54/44 deg F as per ASHRAE standards) chilled water in /out temperature and heat pump operates at lower evaporating temperature depending on the ambient temperature and high condensing temperature required for winter heating.
The following different options are available for winter heating:
1. A reversible heat pump works as a chiller during summer conditions, which produces chilled water at 12/7 deg C ( 54/44 deg F as per ARI conditions) .During winter conditions the refrigerant flow direction is reversed ,the evaporator becomes condenser and rejects the heat inside conditioned space for heating. Waste heat source can be used to achieve the maximum efficiency of the heat pump. Different types of heat pumps like gas fired heat pump, geothermal heat pump are used.
2. Electric heaters which are placed inside conditioned space. A 1 KW space heater produces less than 1 KW of heat. The heat pump with 1KW of input power can produce as high as 4 KW of heat.
3. Steam /water Boiler with circulating pumps and indoor units/Air Handling units for heating. This option can become viable for large residential /commercial building where central boiler for heating is used.
Following is detailed comparison of electric heater/heat pump/boiler for winter heating: