How HVAC Components Work Together in Your Home

How HVAC Components Work Together in Your Home

April 18, 2017

The components of your HVAC system work as a team to keep you comfortable in the humid Des Moines summers and ward off the winter chill, too. When you understand how your HVAC components work together, you'll be better able to care for your system.

Furnace/air handler

These components are found in the indoor unit, the large metal cabinet inside your house. The main part of the furnace is the burner assembly, where fuel is released and burned to create heat. The heat exchanger above the burner assembly transfers heat into the air that's blown over it by the blower fan, which is also inside the indoor unit. The heated air is then blown further out to your rooms.

Evaporator coil

This component consists of two panels positioned side by side or in an A formation. The panels contain metal tubes through which cold refrigerant moves. The cold refrigerant absorbs heat from the air the blower fan blows over it, cooling the air. Near the evaporator coil is the refrigerant metering device, which controls refrigerant flow.


The outdoor unit of your air conditioner is where this component sits. It's connected to the evaporator coil by copper refrigerant lines that carry refrigerant back and forth. The condenser receives hot gaseous refrigerant from the indoor evaporator coil and condenses it, further raising its temperature. The refrigerant then moves to the outdoor coil where it releases its heat, turns back into a liquid, and flows to the house to continue the cycle.


Your ducts are passages running through your walls, floors, and ceilings carrying warm or cool air from the HVAC air handler to the air registers in each of your rooms. They're made of sheet metal, fiberboard or flexduct (a coil of plastic-wrapped wire).

Ducts that deliver conditioned air are called supply ducts. Your duct system should also have at least one return duct that carries air from your rooms back to the air handler to increase the system's efficiency.

If you have more questions about your HVAC components, a heating and cooling technician can help.

Make Sure Your HVAC System is Working

Our goal is to help educate our customers in the greater Des Moines, Iowa area about energy and home comfort issues (specific to HVAC systems).