When it’s time for an AC replacement, a heat pump is worth considering

Most San Diego homes with central air conditioning have it in the form of a split system: an outdoor condenser and an indoor air handler or coil connected to a gas furnace. When the AC condenser dies or reaches the end of its useful life, the replacement decision offers a choice: put in another central AC, or step up to a heat pump.

For most San Diego homeowners, that decision deserves more thought than it usually gets.

What a heat pump replacement actually involves

When you replace a central AC condenser with a heat pump, you are swapping the outdoor unit and potentially the indoor coil or air handler. The ductwork, thermostat wiring, and refrigerant line set may or may not need to be replaced depending on their condition and the new equipment’s specifications.

Here is what typically changes:

Outdoor unit: The old condenser comes out, the new heat pump condenser goes in. This is the same footprint and a similar installation process. Most heat pump condensers are similar in size to the AC units they replace.

Indoor coil or air handler: If you currently have a standalone air handler (a self-contained blower and coil), it may be compatible with the new heat pump. If you have an evaporator coil sitting on top of a gas furnace, you may be able to keep the furnace and coil and run what is called a dual-fuel setup (see below), or replace the coil and keep the furnace as backup heat. Some installations call for replacing the coil or air handler to match the new equipment’s refrigerant type (most new systems use R-410A or the newer R-32 or R-454B refrigerants replacing R-22 systems from the 2000s).

Thermostat: A heat pump requires a thermostat that can handle both heating and cooling from the same outdoor unit, including the defrost cycle. If your current thermostat is a simple cooling-only or heating-and-cooling thermostat for a split system, it probably needs an upgrade. Smart thermostats compatible with heat pumps are available from Ecobee, Nest, and others and add meaningful control over the system.

Refrigerant lines: If the existing lines are in good condition and compatible with the new equipment, they can often be reused after cleaning and testing. Older homes with R-22 refrigerant lines need evaluation for compatibility. Your installer should assess this as part of the quote.

The dual-fuel option

If your home has a gas furnace and you are not ready to move fully away from gas, a dual-fuel heat pump setup is a middle path. A heat pump handles all the cooling and handles heating above a certain outdoor temperature threshold (often around 35-40°F). Below that threshold, the gas furnace takes over. The system switches automatically.

In San Diego, where temperatures below 35°F are rare except in backcountry areas, the gas furnace in a dual-fuel setup rarely activates. It serves as a backup for the coldest days and gives you peace of mind if you are concerned about heat pump heating performance. The tradeoff is that you are maintaining two systems: the heat pump and the furnace.

For most coastal and inland valley San Diego homes, a heat pump alone handles heating loads without needing a gas furnace backup. The dual-fuel setup is more relevant in Julian, Alpine, or other higher-elevation areas where the furnace would actually see regular use.

What happens to the old AC

Your installer should haul away the old equipment. Refrigerant must be recovered by a certified technician before the equipment is removed. This is a federal EPA requirement. Confirm that your installer is EPA 608 certified for refrigerant handling and that the old refrigerant is being recovered properly, not vented.

Electrical requirements for a heat pump

Heat pumps generally draw more amperage than a comparably sized central AC, particularly at startup. Your existing dedicated circuit should be evaluated to confirm it can handle the new load. Older homes in neighborhoods like Normal Heights, City Heights, or University Heights that have not had electrical panel upgrades may have 100-amp service, which can be a constraint when adding heat pump loads. Your installer should confirm circuit compatibility as part of the assessment.

Permit requirements

A heat pump replacement is a permitted installation in San Diego County and most incorporated cities. The permit covers the mechanical installation. Any electrical work, including new circuits or circuit upgrades, requires a separate electrical permit from a licensed electrician.

Some homeowners try to avoid the permit to speed up the project. Skip it and you void your manufacturer warranty, create a disclosure issue at resale, and miss the inspection that confirms the system was installed to current code. Every legitimate heat pump installation should include a pulled and passed mechanical permit.

What to check before signing a quote

When getting quotes for an AC-to-heat pump replacement:

  • Ask for the specific equipment model, not just the brand and capacity
  • Ask whether the existing air handler or coil is compatible or needs replacement
  • Ask what happens to the thermostat
  • Ask whether refrigerant line replacement is included or needs evaluation
  • Confirm the quote includes permit fees
  • Ask for the SEER2 and HSPF2 ratings

For more on what to look for when hiring, see the guide to how to hire a heat pump installer in San Diego.

Heat Pro SD connects homeowners with experienced, insured C-20 HVAC crews throughout San Diego County. Call (858) 925-5546 to get a quote for your replacement project, or visit the San Diego heat pump service area page.

Can I replace just the outdoor AC unit with a heat pump and keep my furnace?

Yes. This is the dual-fuel approach. The heat pump handles cooling and handles heating above a threshold temperature, and the gas furnace handles heating below that threshold. Your installer will need to confirm that the existing indoor coil or air handler is compatible with the heat pump and may need to update the thermostat.

How long does an AC to heat pump replacement take?

Most standard residential replacements are completed in one day. More complex installations involving coil or air handler replacement, electrical work, or line set replacement may run two days.

Do I need to replace my ductwork when switching to a heat pump?

Not automatically. If your existing ductwork is in good condition and properly sized for the new equipment, it can be reused. Duct testing is required for permitted installations and will identify any significant leakage that should be addressed before or during the project.

Ready to get an estimate? See our heat pump services or call (858) 925-5546 to connect with an insured C-20 crew serving San Diego County.