Duct leakage testing involves a pass/fail test by pressurizing an HVAC system to find duct leakage, which is air leaking through holes, cracks, or seams in ductwork. Ensuring minimal duct leakage in a system is important, as the leakage will reduce both equipment efficiency and air volume.
Room pressure testing compares the pressure differential between one room to an adjacent room. Having a room positively pressurized can help keep a space clean, whereas negatively pressurized can help contain a dirty space from the rest of the building. The pressure can also affect the door to the space by making it hard to open or unable to close if excessively pressurized. Room pressures can be adjusted by balancing the HVAC system with outdoor air or exhaust air.