A heat pump represents a growing segment of the HVAC industry. In practical terms, it is a reversal of how the air conditioning system works. Where air conditioners are used for cooling air, a heat pump can be used for cooling or heating if is used in the right conditions. Therefore, it is necessary to employ a heat pump where temperatures are more moderate. The Mid-south is one such area where the unit can be used for cooling in the Summer months and be converted into a heating application when the temps are a bit cooler. In areas such as Florida or California where temperatures are mostly warm, it is best to use an air conditioner only.
Heat pumps use a reverse refrigeration cycle as opposed to the regular vapor compression cycle of an ac unit. Heat pumps use the condenser section to generate heat whereas an air conditioner uses it to reject heat. A heat pump uses a small amount of energy to move heat from one location to another and can be reversed to cool a building or office space. Air conditioners and heat pumps work in a very similar way. The biggest advantage to a heat pump is there is no need to have separate units to handle heating and cooling. Since the heat pump is only transferring heat it can operate by electricity and does not rely on the burning of fuel to accomplish the process.
In the cooler months, a reversing valve reroutes the refrigerant path making the outdoor condensing coil function as the evaporator and the indoor coil as the condenser. The outdoor heat is absorbed by the evaporator and then used by the condenser to heat the indoor space. However, there is one remaining problem. Now that the evaporator is outside and is tasked with absorbing heat it must operate at temperatures lower than the outside air. This low operating temperature causes ice to build-up on the outside of the evaporator. Consequently, the unit must go through a defrost cycle where auxiliary heat must be used to provide indoor heat during this stage.