For total leakage:
(a) Verify that supply and return plenums and all the collars, connectors, transition pieces, duct boots, and return boxes have been installed. If a platform or other building cavity is used to house portions of the air distribution system, it shall contain a duct, be lined with duct board or sheet metal, and all duct connectors and transition parts shall be installed and sealed. The platform, ducts, and connectors shall be included in the total leakage test. All joints shall be inspected to ensure that no cloth backed rubber adhesive duct tape is used.
(b) Seal all the supply duct boots and return boxes except for one return duct box.
(c) Attach the fan flowmeter device at the unsealed return duct box.
(d) Insert a static pressure probe at one of the sealed supply duct boots located close to the supply plenum or at the supply plenum.
(e) Adjust the fan flowmeter to maintain a positive 25 Pa (0.1 inches water) pressure in the duct system with respect to the outside, or with respect to the building space with the entry door open to the outside.
(f) Record the flow through the flowmeter; this is the leakage flow at 25 Pa (0.1 inches water).
(g) Divide the leakage flow by the total air handler airflow determined by the procedure in Section RA3.1.4.2 and convert to a percentage. If the leakage flow percentage is less than or equal to the compliance criterion from Table RA3.1-2 the system passes.