Do You Need a Permit to Replace an AC or Furnace in California?

Yes. In California, replacing a central air conditioner, heat pump or furnace requires a building or mechanical permit from your city or county, even for a like-for-like swap. The CEC's 2025 Single-Family Residential Compliance Manual states that "installation of a space conditioning appliance (other than a plug-in room appliance) requires a building permit." The change-out itself has to meet Title 24, and the permit is how the building department checks it. The requirements include duct leakage testing and, depending on equipment and climate zone, refrigerant charge and airflow verification by an independent ECC-Rater (formerly HERS rater).

Window units and other plug-in room appliances are the exception. Hard-wired, ducted, or line-set equipment is generally permitted work; check your building department for any local exemptions. That includes mini-split heat pumps sold as DIY kits.

Normally the licensed contractor doing the work pulls the permit. The Contractors State License Board (CSLB) advises homeowners to make sure their contractor holds an active C-20 (Warm-Air Heating, Ventilating and Air-Conditioning) license in good standing. You can check the license on the CSLB website.

Some cities let homeowners pull an owner-builder permit for their own home. If you do, you take on the contractor's responsibilities: scheduling the ECC-Rater, completing the installer paperwork and passing the inspections. Ask your building department before you take that route.

A quote with "no permit needed" or "permit optional, saves you money" is a red flag. An unpermitted change-out skips the inspections that check gas, electrical, venting and condensate work, not just the energy tests.

The CEC allows an exception for "urgent alterations (e.g., HVAC changeouts)": where the building department doesn't require plans with the permit application (Section 10-103), the compliance certificate can be registered after the permit is issued, as long as it happens before final. Some departments still want the compliance certificate registered before issuing the permit. The energy requirements in Section 150.2(b)1 still apply:

• Duct sealing verification. Replacing the air handler, outdoor condensing unit, or cooling or heating coil triggers a duct leakage test on the connected ducts. The limits are 10 percent of system airflow total leakage, or 7 percent leakage to outside. If neither can be met, all accessible leaks are sealed and verified by the rater with a smoke test and visual inspection. Ducts or equipment in a garage have additional sealing requirements. Exceptions include ducts with less than 40 linear feet, ducts already sealed and verified in an earlier test, and ducts made or sealed with asbestos.
• Refrigerant charge and airflow verification. When refrigerant parts such as the compressor, coils, metering device or piping are replaced, refrigerant charge and minimum airflow (300 cfm per ton for most ducted systems, 250 for small duct high velocity) must be verified. Under the 2025 code (permits applied for on or after January 1, 2026), this applies to air conditioners in Climate Zones 2 and 8 through 15 and to heat pumps in all climate zones. Under the 2022 code, heat pumps were also limited to Climate Zones 2 and 8 through 15. Complete-replacement packaged units charged at the factory are exempt from the charge test (airflow still applies), and performance-path projects follow their CF1R.
• Setback thermostats. When refrigerant-containing parts of an AC or heat pump are replaced, or the whole system is replaced, all thermostats on that system must be setback thermostats.
• Complete replacement systems. When the equipment and the duct system are replaced (the code counts a duct system as replaced when at least 75 percent of it is new), more requirements apply, including the new-construction rules for fan power use and airflow (generally 350 cfm per ton with a watts-per-cfm limit), filter requirements, new duct insulation levels and a tighter duct leakage limit.
• Heating fuel limits. Altered or replacement space heating cannot use electric resistance as the primary heat source, except in limited cases where the existing heat is already electric resistance.

The full field-test process is covered in our guide on whether you need a HERS rater for HVAC replacement. Charge testing is covered in refrigerant charge verification.

A change-out that needs field verification produces three types of Title 24 documents. The CF1R-ALT-02 certificate of compliance can be registered by final where the building department allows it. The installer's CF2R certificates of installation follow, and then the rater's CF3R certificates of verification. These are registered in an ECC-Provider data registry, and the building inspector checks them before closing the permit. Copies are supposed to be left with the homeowner. If yours are missing, see how to find CF2R and CF3R documents.

You'll pay the permit fee, which varies by jurisdiction, and the rater's fee for testing. The published rater prices we found for a typical change-out verification ranged from a few hundred dollars to around a thousand, depending on home size and how many tests are bundled. Our HERS rater cost guide has the details. Duct repair is the less obvious cost. If old ducts leak badly, sealing or replacing them can add to the job. Ask your contractor to inspect the ducts and include likely sealing work in the quote.

• Enforcement. A building department that finds unpermitted work can require a permit after the fact. That usually means fees, inspections and possibly opening up work for inspection. Rules and penalties vary by city.
• Home sale. California's Real Estate Transfer Disclosure Statement (Civil Code Section 1102.6) asks sellers whether they know of "alterations or repairs made without necessary permits." Equipment newer than the last permit on file can come up during a sale and turn into a negotiation point or a request to permit and test the system before closing.
• Equipment and comfort. Without the required duct test and charge check, nobody independently measures duct leakage or refrigerant charge. Leaky ducts and wrong charge are exactly what the tests are designed to catch.
• Rebates and financing. Some incentive programs ask for permit or compliance documentation. Read the program rules before you count on a rebate for unpermitted work.

Most contractors already work with a rater, but you can choose your own or compare options. Search certified ECC and HERS raters by city, county or climate zone in the Title 24 Directory, or start with Los Angeles.