Similar to air tightness testing, each cubic foot of air that leaks out is required to be replaced by the same amount blown back in by the fan. Therefore, once the correct amount of displaced air moving through the fan has been measured, you have quantified the duct leakage at the testing pressure.
What is Air Duct Testing?
The basic idea behind using an air duct test to test for duct leakage is:
- Use a calibrated fan to pressurize the duct system.
- Measure the airflow through the fan with the duct system at pressure.
Why Test Ducts for Leaks?
- 10-30% of heated/cooled air lost through ductwork
- Leaky supply ducts don’t deliver air where needed
- Leaky return ducts add load
- Improving indoor air quality
- Leaky returns can pull in air from uncontrolled spaces, causing humidity problems and contaminants
When to Test?
It is strongly recommended to test when a new heating and/or air conditioning unit is being installed as its is much easier and cheaper to rectify any problems at that stage.