The New Title 24 Rules

Residential

The new rules apply to zones 2, 9, 10, 11, 12, 13, 14, 15, and 16. The rest are exempt. A more detailed breakdown of climate zones can be found here.

Some of the new rules are as follows.

• There must be at least 40 linear feet of ductwork located in unconditioned space for the new rules to apply.

• Ductwork made or insulated with asbestos is exempt.

• Duct testing is required when any of the following components are replaced:
  air handler, furnace, outdoor/condensing unit, heating or cooling coil, furnace heat exchanger, package unit

• The new rules also apply when replacing 40 linear feet or more of ductwork that's located in unconditioned space.

• The maximum allowed leakage is 15% of airflow on existing ductwork. Or you can reduce total leakage by 60%. Or you can use a whole house blower door test plus duct leakage test to get duct leakage to the outside of the house down to 10% or less. Or you can seal all accessible leaks and then hire a HERS rater to verify that with smoke. ANY of the four standards above taken at face value will fulfill the requirement on existing ductwork.

• The maximum allowed leakage is 6% of airflow on completely new duct systems.

• Ductwork that falls under the new rules may first be tested for leakage by the contractor, depending on what method is going to be used to verify leakage. The contractor does not have to be certified to perform the test. The test does not have to be performed at the same time as the replacement work. But the testing, whether done by the contractor or a HERS rater must be completed before the building permit is signed off.

• The contractor may hire another firm to test and seal ductwork that falls under the new rules. A HERS Rater can be hired to test ducts but a HERS Rater may not seal ducts. At all times responsibility for compliance remains with the original contractor.

• For ductwork that falls under the new rules Form CF-6R must be filled out when the work is completed.

• If the contractor chooses to verify duct leakage through sampling then a HERS Rater must be hired to review each Form CF-6R. For every seven forms reviewed the rater must pick one and go to the job location. The rater will perform a duct leakage test to verify the contractor's results.

• The HERS Rater may not be an employee of the HVAC contractor. An HVAC contractor can also be a HERS rater but he may not review or test his own systems.

There are alternatives to duct testing written into the new rules. For our local climate zone of 12 the most interesting of them is the .92 AFUE option. In some cases upgrading to a .92 AFUE furnace costs less than duct testing and sealing. Though in the long term duct sealing could potentially pay for itself by virtue of lower utility bills. If any of these exemptions apply duct testing does not have to be performed.

Commercial

What follows is a brief and incomplete summary of some of the new Title 24 duct testing rules as they apply to commercial duct systems.

• At least 25% of duct surface area must be outdoors or in unconditioned space for the new rules to apply. This is in contrast to the 40 foot rule for residential systems.
• The new rules apply for all climate zones. There are no climate zone exemptions as is the case with residential systems.
• Ductwork made or insulated with asbestos is exempt. Variable air volume systems are exempt. Single systems that serve 5,000 square feet or more are exempt.
• Duct testing is required when any of the following components is replaced: air handler, furnace, outdoor/condensing unit, heating or cooling coil, furnace heat exchanger, package unit
• The maximum allowed leakage is 15% of airflow on existing ductwork. Or you can reduce total leakage by 60%. Or you can seal all accessible leaks and then hire a HERS rater to verify that with smoke. ANY of the three standards above taken at face value will fulfill the requirement on existing ductwork.
• The maximum allowed leakage is 6% of airflow on completely new duct systems.
• The verification procedures involving Form CF-6R and a HERS Rater are the same for commercial as they are residential.

A duct system can be exempted from duct testing on single zone commercial air conditioners that meet certain SEER and/or EER standards. Please consult your commercial HVAC contractor for further details.

Please note that the information on this page was derived from the seminar entitled "Title 24 HVAC System Change-Outs: Duct Testing Requirements for Residential and Non-Residential" as presented by Doug Beaman at PG&E's Energy Training Center in Stockton, CA. The information on this page should not be considered comprehensive. Nor can High Performance Heating & Air guarantee 100% accuracy. As with any sweeping changes in the law, understanding and interpretation is subjective and flowing.

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