Duct Blower Test

This is a primary audit test. This test measures the total air leakage in and out of the heating and cooling ducts, and also the total air leakage to the outside from the ducts. The duct blower test uses a small fan to pressurize the duct system to a set pressure (usually 25 Pascals), while a calibrated pressure gage calculates the amount of air leaking through joints and gaps in the ducts. During this test, the auditor will mask off your heating and cooling registers with a temporary tape. The fan will connect through a flexible tube to the return register or directly to the furnace cabinet. With the majority of energy loss in a typical house occurring through air leaks, the blower door and duct blower tests are the two most important tests of the energy audit.