Why is Duct Testing Important?

In residential central heating and cooling systems, the conditioned (heated or cooled) air is delivered to each room of the home through a "supply" duct system, the first half of the duct system. These ducts are used as pathways to deliver air to each room in the home and the "return" duct system or second half of the duct system, returns air to the heating and cooling system. The condition of both duct systems is vital to the overall efficiency of the heating and cooling system and the comfort levels in each room of the entire home. 

Energy loss is not the only concern, duct systems can also affect the indoor air quality of a home. If the return duct system is leaky, it could be drawing stale or polluted air into the duct system and distributing it throughout the home. This air could come from an attic, combustion air from the gas furnace, stove, water heater, or the outside. If the supply duct system is leaky, the home can become depressurized and air from outside may be drawn into the home through infiltration. Either situation may contribute to breathing problems such as allergies and asthma.

Now that you know that duct systems can affect both energy usage and indoor air quality, how do you know if your duct system is in good condition? The most reliable and cost-effective way to determine this is to have a "duct test" using the proper test equipment. Duct testing is the process of using calibrated mechanical equipment to measure the amount of airflow that is lost through the duct system when it is pressurized to its normal operating pressure. While some joints or seams may have only small leaks, other sections may be completely disconnected.

Duct testing can indicate the relative leakiness of the ducts and help determine if the duct system should be sealed, repaired, or renovated. Duct testing is strongly recommended when a new heating and air conditioning unit is being installed. If the existing duct is leaky and inefficient before the new unit is installed, it will still be leaky and inefficient after the new unit is installed unless the ducts are sealed. It does not make sense to install a new energy efficient heating and air conditioning unit unless the duct system is also energy efficient and provides the correct amount of heated or cooled air to each room.