New Duct Sealing Regulations for Home Owners

As of October 1, installing or replacing certain heating, ventilating and air conditioning (HVAC) equipment may trigger a requirement to test and, if necessary, properly seal the existing ducts connected to HVAC equipment. The duct sealing must then be independently verified by a certified home energy rater. If a building permit is required, the local building department may not issue a permit for installing HVAC equipment until the ducts are properly sealed as verified by a certified home energy rater. If a homeowner circumvents permit requirements by changing out HVAC equipment without the necessary duct sealing, the homeowner must disclose that fact to a prospective buyer on the Real Estate Transfer Disclosure Statement.

From the California Energy Commission's web site (PDF link):

Beginning October 1, 2005, you must have your home’s ducts tested for leaks when you have a central air conditioner or furnace installed or replaced. Ducts that leak 15 percent or more must be repaired to reduce the leaks. After your contractor tests and fixes the ducts, you choose whether to have an approved third-party field verifier check to make sure the duct testing and sealing was done properly or to have your house included in a random sample where one in seven duct systems are checked.

Duct sealing is not required in the following situations: 1) when homes are in specific coastal climates; 2) when systems have less than 40 feet of ductwork in unconditioned spaces like attics, garages, crawlspaces, basements or outside the building, or 3) when ducts are constructed, insulated or sealed with asbestos. There also are specific alternatives that allow high efficiency equipment and added duct insulation to be installed instead of fixing duct leaks.

You also should know that any contractor failing to obtain a required building permit and failing to test and repair your ducts is violating the law and exposing you to additional costs and liability. Real estate law requires you to disclose to potential buyers and appraisers whether or not you obtained required permits for work done on your house. If you do not obtain a permit, you may be required to bring your home into compliance with code requirements for that work and you may have to pay penalty permit fees and fines prior to selling your home.

In #1 above, it refers to 'specific coastal climates'... I have no idea what that means, but obviously leaves some ambiguity in the new law... Also, per #3, many of San Francisco's homes still have asbestos ducts, which would also exempt you from the new law. Check with your furnace installer before they get too far into a project... Many installers don't pull proper permits and that could affect your resale...