Size of an HVAC Return Duct

Size Variance

• Not all HVAC ducts are created equal, and the reason lies in furnace and AC construction itself. As technology has changed, the way that HVAC systems work has also evolved. In houses that are decades old, the HVAC ducts tend to be very large. Younger houses have smaller ducts, while the most modern HVAC systems may actually work best with larger ducts once again. The power and size of the system is important, as is how the system operates.

Importance of Size

• You should not try to fit a HVAC system with ductwork that is the wrong size. If the ductwork is too large, the air will not move quickly enough and you will lose heat (or cold air) while you run your units. If you have ducts that are too small, the air will not move out quickly enough, potentially causing the furnace to overheat and the air conditioner to use extra energy and drive up the utility bill.

Comparisons

• If you are not sure that your HVAC ducts are the right size for your system, take a look at the average size of your return-air ducts and of the ducts located on your HVAC system itself. These ducts should roughly match in size. If they are considerably different in size, you may have a ductwork-sizing problem. If you are not sure, hire a contractor that specializes in HVAC work to take a closer look.

Remodeling for Size

• You can remodel HVAC return ducts to increase or decrease the size, but the process can be expensive depending on what type of house you have and how much ductwork needs to be remodeled. Compare prices for the remodel using ductless HVAC systems or running new ducts along the outside of your house to see if you can save money with an alternate plan.