Heat Pump Installation in San Diego: What to Expect, Step by Step
A typical heat pump installation in San Diego takes one to three working days on site, after a home assessment, a load calculation, a written quote and a city or county permit. Replacing an existing AC and furnace on sound ductwork is usually the fastest job; adding ductless zones, new ducts or an electrical panel upgrade adds time. In San Diego’s mild climate, one heat pump handles both cooling and heating, so it typically replaces both the AC and the furnace.
Below is each step of the process, what California code requires along the way, and what you can do to make install day go smoothly.
Step 1: Home assessment and load calculation
A proper installation starts with a visit, not a price over the phone. The installer should look at:
- The size, insulation and window exposure of each room, and ceiling heights
- Existing ductwork – its size, condition and whether it leaks or runs through a hot attic
- The electrical panel – available capacity and breaker space for the new system
- Where the outdoor unit can sit with proper clearances, drainage and limited noise toward bedrooms or neighbors
From this the contractor runs a load calculation (often called Manual J) to size the system. Sizing by square footage alone is the most common cause of a system that short-cycles, feels clammy in summer or runs nonstop on hot inland days. Our guide on how many mini splits you need explains how room-by-room sizing works for ductless systems.
Step 2: Choosing the type of heat pump
| System type | Best for | Notes |
|---|---|---|
| Ducted (central) heat pump | Homes with good existing ductwork | Replaces the AC condenser and furnace; uses your current vents |
| Ductless mini split | No ducts, additions, garages, rooms that are always too hot or cold | Each indoor head is its own zone; no duct losses |
| Ducted mini split / multi-zone | Mixed homes – some ducted areas, some not | One outdoor unit can serve ducted and ductless indoor units |
| Dual fuel (heat pump + gas furnace) | Homes keeping a newer furnace | Rarely needed in coastal San Diego; sometimes chosen in higher inland areas |
Since 2023, new split-system heat pumps must meet at least 14.3 SEER2 for cooling and 7.5 HSPF2 for heating under federal efficiency standards, and new systems now use lower-GWP refrigerants such as R-454B or R-32. Higher-efficiency inverter models cost more upfront but run quieter and hold temperature more evenly. See our heat pump installation and ductless mini split installation pages for the systems we install.
Step 3: Quote, permit and scheduling
A good quote lists the exact model numbers of the outdoor and indoor units, the line set and electrical work, any duct changes, the permit, removal of old equipment, and both the manufacturer and labor warranty terms. Ask whether the price includes the permit and any required testing.
In California, replacing or adding a heat pump requires a mechanical (and usually electrical) permit from your city or the County of San Diego. Under the state’s Title 24 energy code, many heat pump change-outs also need third-party HERS verification – for example of refrigerant charge, airflow or duct leakage – before the permit is closed. A licensed C-20 HVAC contractor pulls the permit and schedules the inspection.
Step 4: Installation day
For a typical replacement, the crew will:
- Protect the work area and shut off power and gas to the old equipment.
- Recover the old refrigerant and remove the old condenser, coil and, when it is being replaced, the furnace.
- Set the outdoor unit level on a pad or wall bracket with the clearances the manufacturer specifies.
- Install the indoor unit – a new air handler or coil for a ducted system, or wall, ceiling or floor heads for ductless zones.
- Run or replace the refrigerant line set, the condensate drain and the control wiring.
- Complete the electrical work: a dedicated circuit, a disconnect at the outdoor unit and the right breaker size.
- Pressure-test and evacuate the system. The lines are tested with nitrogen for leaks, then a vacuum pump and micron gauge pull out air and moisture. Skipping or rushing this step is one of the most common causes of early compressor problems.
- Charge and start up. Refrigerant is adjusted for the actual line length, then the system is run in both cooling and heating mode.
Step 5: Testing, inspection and walkthrough
After startup, the installer checks airflow, temperature split, refrigerant pressures and condensate drainage, and sets up the thermostat or controllers. Then comes the city or county inspection and, where required, the HERS verification visit. Before the crew leaves, you should get a walkthrough of the controls, filter location and cleaning schedule.
Register the equipment. Most manufacturers extend their parts warranty only if the system is registered within 60 to 90 days. For Mitsubishi systems, a registered install by a Diamond Contractor gets 12 years of parts and compressor coverage – see what a Mitsubishi Diamond Contractor is.
How long does it take?
| Job | Typical time on site |
|---|---|
| Replace AC/furnace with a ducted heat pump on existing ducts | 1-2 days |
| Single-zone ductless mini split | About 1 day |
| Multi-zone ductless system (3-5 rooms) | 2-3 days |
| New ductwork or electrical panel upgrade | Add 1-3 days |
Permits, inspections and HERS verification add calendar time but usually not extra time in your home.
San Diego specifics
- Coast vs. inland. Coastal homes need salt-air-resistant placement and hardware for the outdoor unit. Inland areas like Escondido, El Cajon, Santee and Poway need systems sized for long stretches of 90°F-plus heat.
- Attic ducts. Many older San Diego homes have ducts in hot attics. Sealing or replacing leaky ducts during the install often makes a bigger comfort difference than buying a higher-efficiency unit.
- Rebates and tax credits. The federal 25C tax credit does not apply to heat pumps installed after December 31, 2025. TECH Clean California and SDG&E incentives open and close by funding cycle – check our rebate program page and ask what is available when you get your quote. Financing is also available.
How to prepare for install day
- Clear a path to the furnace, attic access, electrical panel and the outdoor unit location.
- Arrange for pets to be away from open doors and work areas.
- Decide on thermostat or controller placement in advance.
- Plan for no cooling or heating for part of the day while the old system is removed.
About Accord Air
Accord Air is a Mitsubishi Electric Diamond Contractor based in Escondido and serving San Diego County. We install ducted and ductless heat pumps, mini splits, central AC and furnaces, and we’re licensed by the Contractors State License Board (license #1152919). Request a quote or call 858-208-8140.
Frequently asked questions
How long does a heat pump installation take?
Replacing an existing AC and furnace with a ducted heat pump usually takes one to two days on site. A single ductless zone takes about a day, and multi-zone systems or new ductwork take longer.
Do I need a permit to install a heat pump in San Diego?
Yes. Heat pump installations need a permit from your city or the County of San Diego, and many also need third-party HERS verification under California’s Title 24 energy code. Your licensed HVAC contractor should pull the permit.
Can a heat pump replace both my AC and my furnace?
Yes. A heat pump cools like an AC and also heats. In San Diego’s mild winters, a correctly sized heat pump heats the whole home without a furnace.
Can I keep my existing ductwork?
Often yes, if the ducts are the right size and in good condition. The installer should inspect them and test for leaks; leaky or undersized ducts should be sealed or replaced.
Is there a federal tax credit for heat pumps in 2026?
No. The federal 25C energy-efficiency tax credit does not apply to heat pumps installed after December 31, 2025. State and utility rebates may still be available depending on current funding.
