Heat Pumps verses Air Conditioners: A Look at the Tech

This graphic explains how the air circulates in a heat pump or air conditioning unit.By Jody Howe

CEC Energy Specialist

Have you ever wondered how a heat pump or air conditioner actually work? Here’s a quick technical breakdown on the units and also how heat pumps are different.

The outside unit where the refrigerant (gas) in the system is pumped (compressed) to a high pressure causing a high temperature rise. The gas flows through the condensing coil where it cools to ambient temperature. As the gas enters the evaporator coil, located in the air handler (inside), it expands causing its temperature to drop rapidly and cools the evaporator coil. Why? The answer is because heat flows from warmer to cooler. We need the refrigerant colder than the indoor air so that it can pull the heat out of it, this is a critical step.

A heat pump can reverse the process by switching the function of the evaporator and the condenser coil to raise temperatures inside the home. The expansion valve is where it happens. This is where the thermodynamic property of gases happens. When gases are allowed to expand freely, their temperatures drop.

Once we get the heat from the air into the refrigerant, it’s a matter of bringing it into the house and then transferring it into the home’s air.