Yes. In San Diego County, replacing an air conditioner, furnace or heat pump requires a building permit, even for a like-for-like swap. Under California's 2025 Energy Code (effective January 1, 2026), replacing an air handler, outdoor unit or coil also triggers duct sealing and third-party verification, now done under the Energy Code Compliance (ECC) program that replaced HERS testing.
Fallbrook Heating & Air pulls and files all legally required permits and handles the mandatory Title 24 duct testing on its replacement jobs. Here's what that involves, so you know what to expect from any contractor.
Do I need a permit to replace my AC or furnace?
Yes. A permit is required to replace an air conditioner, furnace or heat pump, including same-size, same-spot replacements. Unincorporated communities (Fallbrook, Bonsall, Rainbow, De Luz) go through San Diego County Planning & Development Services; incorporated cities issue permits through their own building departments.
The permit isn't just paperwork. It brings an inspector to check the gas, electrical, venting and refrigerant work, and it links the installation to the state's energy-code verification. It also creates a public record that the work was done legally, which matters when you sell the house.
Who issues HVAC permits in North County?
It depends on whether your address is inside a city. Fallbrook, Bonsall, Rainbow, De Luz, Pala Mesa and Valley Center are unincorporated, so San Diego County Planning & Development Services issues the permit. Oceanside, Vista, San Marcos, Escondido, Carlsbad and Encinitas issue their own. Temecula and Murrieta are in Riverside County and have their own building departments.
| Where you live | Permit issued by | Notes |
|---|---|---|
| Fallbrook, Bonsall, Rainbow, De Luz, Pala Mesa, Valley Center (unincorporated) | San Diego County Planning & Development Services (PDS) | County building permit |
| Oceanside | City of Oceanside building department | City permit |
| Vista | City of Vista building department | City permit |
| San Marcos | City of San Marcos building department | City permit |
| Escondido | City of Escondido building department | City permit |
| Carlsbad | City of Carlsbad building department | City permit |
| Encinitas | City of Encinitas Development Services | City permit |
| Temecula (Riverside County) | City of Temecula building department | Also in the South Coast AQMD air district |
| Murrieta (Riverside County) | City of Murrieta building department | Also in the South Coast AQMD air district |
Permit fees vary by jurisdiction and job, so we don't list them here. Your contractor's quote should say whether the permit is included.
What does Title 24 require when I replace HVAC equipment?
Under the 2025 Energy Code, replacing an air handler, outdoor condensing unit or cooling coil means the ducts must be sealed and the result verified by an independent third-party rater. Additional verification can apply depending on your equipment and climate zone. The rules sit in Title 24, Part 6, and the California Energy Commission maintains them.
"Title 24" is the California Building Standards Code. Part 6 is the Energy Code, which the CEC updates on a regular cycle. The 2025 version took effect January 1, 2026. For existing homes, the rules that matter most are the "alteration" requirements: what has to happen when you change out equipment, rather than build new.
What triggers duct sealing and testing?
- Replacing the outdoor AC or heat pump unit
- Replacing the indoor cooling coil
- Replacing the air handler or furnace that moves air through the ducts
Exactly which tests apply can depend on the equipment type and the climate zone, so a good contractor confirms the requirements for your address when pulling the permit.
What is HERS testing, and what is ECC?
HERS was the program that certified independent raters to verify energy-code work like duct sealing. Under the 2025 Energy Code it was replaced by the Energy Code Compliance (ECC) program, and raters are now ECC-Raters. The job is the same: an independent person tests your system and confirms it meets code.
Because the rater is independent of the installer, the verification protects you. It means someone other than the company you paid has checked the duct leakage and other required items.
How does a duct leakage test work?
The tester seals the supply and return registers, connects a calibrated fan to the duct system, and pressurizes it. The fan measures how much air it takes to hold that pressure, and that equals how much leaks out. If the leakage is over the allowed limit, the ducts are sealed further and retested.
- New equipment goes in. The installer replaces the unit and connects it to the existing ducts.
- Ducts are sealed. Leaky joints, boots and plenums are sealed with mastic or approved tape.
- Installer tests. The installer runs the leakage test and documents the results for the permit.
- Third-party verification. An ECC-Rater independently verifies the required items.
- Final inspection. The building inspector signs off and the permit closes.
On our jobs, we seal the ducts and contract a licensed ECC-Rater (HERS rater), who tests them and confirms the result. When only the equipment is replaced, the existing ducts and equipment must leak no more than 15%; new ductwork must test at 5% or less. Older homes with ducts in hot attics often need the most sealing work, and that work also cuts wasted cooling. Learn more on our Title 24 duct testing page.
Does the new code force me to switch to a heat pump?
No. The 2025 Energy Code does not require a heat pump when you replace the AC or furnace in an existing home. A proposed provision that would have encouraged heat pumps for AC replacements was dropped before adoption. You can replace your system with the same type, though a heat pump can still be a good choice for our mild winters.
If you're weighing the two, our heat pump vs furnace guide compares them for North County homes.
What if my contractor says I don't need a permit?
Be careful. Skipping the permit can save a little up front but leaves you holding the risk: no inspection of gas, electrical or venting work, no duct verification, and a record gap that can surface at resale. If something goes wrong, unpermitted work can also complicate insurance claims.
- Ask whether the permit is included in the price, and in whose name it will be pulled.
- Check the contractor's licence on the CSLB website. HVAC work calls for a C-20 licence. Ours is CA Lic. C-20 #638959.
- Ask who does the third-party verification and when it will be scheduled.
- Keep the closed permit and the verification paperwork with your house records.
Temecula and Murrieta: anything different?
The permit comes from the city's own building department, and both cities sit in the South Coast Air Quality Management District, which regulates furnace emissions under Rule 1111. In June 2025, its board rejected a proposed zero-NOx furnace amendment, so the existing rule stays. Rules change, so check current status.
San Diego County is not in the South Coast AQMD, so that rule doesn't apply in Fallbrook, Oceanside or the other San Diego County communities we serve.
Planning a replacement? Our AC replacement cost guide explains how the permit and testing fit into the price, and our furnace installation page covers heating changeouts.
Frequently asked questions
Do I need a permit to replace my AC in San Diego County?
Yes. Replacing an air conditioner, furnace or heat pump requires a building permit, even when the new unit goes in the same spot. In unincorporated areas like Fallbrook, Bonsall, Rainbow and De Luz, the permit comes from San Diego County Planning & Development Services. Cities such as Oceanside, Vista and Escondido issue their own.
What is a Title 24 duct test?
It's a pressure test that measures how much air leaks out of your ducts. Under California's 2025 Energy Code, replacing an air handler, outdoor unit or coil triggers duct sealing, and a third-party rater verifies the result. That verification now runs under the Energy Code Compliance (ECC) program, which replaced the old HERS program.
Is HERS testing still required in 2026?
The same kind of third-party verification is still required, under a new name. Starting with the 2025 Energy Code, effective January 1, 2026, HERS verification runs under the Energy Code Compliance (ECC) program, and HERS raters are now called ECC-Raters. The goal is unchanged: an independent check that the work meets code.
Who pulls the permit, me or the contractor?
Your licensed HVAC contractor should pull the permit in their own name and schedule the inspections and third-party verification. Be cautious if a contractor suggests you pull an owner-builder permit for work they're doing. Fallbrook Heating & Air pulls and files all legally required permits on its jobs.
Does the 2025 Energy Code make me install a heat pump?
No. California's 2025 Energy Code does not require a heat pump when you replace the AC or furnace in an existing home. A proposed provision that would have pushed heat pumps for AC replacements was dropped. You can replace like for like, though a heat pump is worth considering on its merits.