REPLACING AN AIR CONDITIONER OR FURNACE IN CALIFORNIA: PERMITS AND TESTING

Each building department we checked issues a permit for this work, and the basic rule is broad. In the version of Section R105.1 of the California Residential Code that Carlsbad adopted in its municipal code (Ordinance CS-498, December 2, 2025), a permit is required before an owner or the owner's agent may “erect, install, alter, repair, remove, convert or replace” any electrical, gas, mechanical or plumbing system.

The exceptions are narrow. Carlsbad's mechanical exemptions cover items such as portable heating appliances, portable cooling units and portable evaporative coolers, plus replacing a part that does not alter the equipment's approval or make it unsafe.

The Contractors State License Board (CSLB) tells homeowners the same in its HVAC checklist: “Make sure your contractor obtains a building permit from your local building department.”

This guide reflects official pages read on October 4, 2026 and is general information, not legal advice. Confirm your scope with the building department before work starts.

Often, yes. The California Energy Commission says buildings whose permit applications are applied for on or after January 1, 2026 must comply with the 2025 Energy Code. Its 2025 Single-Family HVAC page says replacing the outdoor unit or the indoor unit of a split system, by itself, triggers the duct sealing and field verification requirements.

Chapter 9 of the Commission's 2025 Single-Family Residential Compliance Manual lists the triggers: an air handler is replaced, the outdoor condensing unit of a split system is installed or replaced, a packaged system is completely replaced, or a cooling or heating coil is installed or replaced. The installer seals the ducts connected to the altered equipment, and an ECC-Rater verifies the result.

• Existing ducts: measured leakage of 10 percent of system airflow or less, or leakage to outside of 7 percent or less.
• If neither target can be met: all accessible leaks must be sealed and verified through a visual inspection and a smoke test. The manual says sampling is not allowed for that inspection and test.
• An entirely new or complete replacement duct system: measured leakage of 5 percent of system airflow or less.
• Exceptions the manual lists: ducts already sealed, tested and certified by an ECC-Rater, duct systems with less than 40 feet of duct, and duct systems that contain asbestos.

The manual explains the Energy Code but is not the code itself. Ask your contractor which tests your job needs and confirm with the building department.

When a refrigerant-containing component is replaced or installed in an existing house, the manual says Section 150.2(b)1F requires the refrigerant charge to be field verified. For air conditioners, that applies in climate zones 2 and 8 through 15. For systems that both heat and cool with refrigerant, the manual applies it in every climate zone. The chapter lists both under what is new for 2025, and the Commission's 2025 Energy Code Overview gives the same zones. Ask your contractor which rule covers your equipment.

When that verification is required, the system must also meet a minimum airflow of 300 cubic feet per minute per ton, or 250 for small duct high velocity systems. In all climate zones, the manual says the thermostat must be upgraded to a digital setback type that meets Section 110.2(c) when a refrigerant-containing component is added or replaced.

The manual states one more rule for heating. If the space heating system is being replaced, the replacement must not use electric resistance as its primary heat source. The exceptions it lists all start from an existing system that is electric resistance.

We do not assign climate zones to cities. Ask your contractor or building department which zone your address is in and which of these tests apply.

If you replaced equipment before, you may remember a HERS rater. The Energy Commission's Energy Code Compliance (ECC) Program page says the ECC Program “replaces the HERS Program.” The field verification and diagnostic testing part of the HERS regulations moved into the 2025 Energy Code, and the page says all HERS raters will be recognized as ECC-Raters. ECC-Providers approved by the Commission train the raters, oversee their work and operate a data registry.

The rater is meant to be independent. Chapter 2 of the compliance manual calls ECC-Raters “independent, third-party agents.” It says they cannot be employees of the builder or subcontractor whose work they are verifying and can have no financial interest in the installation.

Two certificates follow. The licensed person responsible for the installation completes and signs a Certificate of Installation (CF2R). When verification is required, the ECC-Rater completes, registers and signs a Certificate of Verification (CF3R).

CSLB publishes HVAC fact sheets for consumers. They advise hiring a licensed contractor in good standing with CSLB and getting a building permit “so the building department can confirm proper installation through an inspection.”

The same packet warns about the shortcut. Without a permit, it says, there will be no independent third-party inspection of the work, and “you may be charged fines and penalties.” Its checklist says to “Beware of any contractor that offers a lower price” to install a unit without a permit.

CSLB's Building Permit Violation Referral form gives the contractor's side: “Failure to obtain a building permit is a violation of Contractors License Law.” The form adds that construction performed without a permit can expose a homeowner to additional liability and costs.

The final inspection is where the installation, the certificates and the testing come together. Chapter 2 of the compliance manual lists what the building department needs before it may approve a dwelling at final inspection. That includes the required Certificates of Installation and, where ECC testing is required, a copy of the Certificate of Verification as registered with an ECC registry.

CSLB's checklist tells homeowners to make sure the building department performs all required inspections, in progress and final, and that there are no correction notices or red tags. The County of Orange describes a permit as a document that, “upon final inspection approval,” gives the owner assurance that the work was done safely and in accordance with state and local codes.

When the job is done, ask for copies of the finaled permit and the certificates.

• Is your license active and in good standing on CSLB's license check?
• Who obtains the permit, and is that written into the contract?
• Which components are being replaced, and does that trigger duct testing?
• If the ducts cannot meet the leakage target, what happens next?
• Does this job need refrigerant charge verification, and which climate zone is my address in?
• Who is the ECC-Rater, and how is that rater independent of the installer?
• Is the thermostat being changed as part of the job?
• Does the contract include the 3-day right to cancel clause that CSLB's checklist tells homeowners to look for?
• Will I get copies of the certificates and the finaled permit?

If you would like help planning a heating or cooling replacement, Golden Empire USA offers a free assessment with a written scope.