Furnace replacement in Fallbrook: 80% and 96% efficient furnaces

When a furnace reaches the end of its life, the choice that matters most is not the brand; it is how efficient the replacement should be for the way your home actually uses heat. Fallbrook Heating & Air has handled furnace replacement in Fallbrook and across North County since 1972, installing both 80% and 96% efficient furnaces. We will help you pick the one that makes sense for a mild climate, not just the one with the bigger number.

80% vs 96% AFUE: which furnace makes sense here?

For many North County homes, an 80% furnace is the sensible choice because winters are short and mild, so the fuel saved by a 96% model takes a long time to repay its higher cost. A 96% furnace makes more sense for larger or draftier homes, colder hillside sites, propane-heated homes, or when venting is simple.

Is a 96% furnace worth the extra cost in Southern California?

Sometimes, but not automatically. A 96% furnace uses about 17 percent less fuel than an 80% furnace for the same heat. In Fallbrook, where December lows average around 41°F and the heating season is short, that saving is real but small, so payback can take many years. It shortens when fuel is expensive or heating use is high.

Here is the kitchen-table version. Look at what you spent on gas or propane for heating last winter. A high-efficiency furnace would cut roughly a sixth of that. If that figure is small, the extra cost of the furnace and its PVC venting may take longer to earn back than you will own the home. If you heat with propane, which often costs more per unit of heat than natural gas, or you run the heat a lot, the math improves.

You will sometimes hear that a high-efficiency furnace always "pays for itself." In a mild climate, that is too simple. We would rather show you both options, priced, and let you decide.

Gas, propane or a heat pump?

If your home has natural gas, a gas furnace is the straightforward replacement. Many rural Fallbrook, De Luz and Rainbow homes have no gas main and heat with propane instead. A heat pump is a third option: it replaces both the furnace's heating and the AC's cooling, and suits our mild winters well.

We install, service and maintain natural gas and propane furnaces, and we install heat pumps. California's 2025 Energy Code does not require you to switch to a heat pump when replacing an existing furnace, so the choice is yours. Our guide to heat pump vs furnace in North County compares running costs and trade-offs.

In Temecula and Murrieta, which fall under the South Coast AQMD rather than San Diego County's air district, the SCAQMD board rejected a proposed zero-NOx furnace amendment to Rule 1111 in June 2025, so the existing rule stays for now. Rules can change; check current status at aqmd.gov.

What does a furnace installation include?

A proper furnace replacement includes sizing the furnace to the house, a permit, safe removal and EPA-compliant disposal of the old equipment, correct venting and a condensate drain for high-efficiency models, gas and electrical connections, any required duct testing and sealing, and a full startup with combustion and safety checks.

1. Estimate. We look at the existing furnace, venting, gas line, ducts and the air conditioner it works with, then price both 80% and 96% options where both fit.
2. Permit. Pulled and filed with San Diego County Planning & Development Services for unincorporated areas, or your city's building department.
3. Removal. The old furnace comes out and is disposed of following EPA procedures.
4. Install. New furnace set, vented (metal or PVC), drain run for condensing models, gas and power connected, and the indoor coil matched if you have central air.
5. Testing. Furnace-only replacements get Title 24 duct testing too. If the ducts leak more than the code allows, we seal them, and a licensed ECC-Rater (HERS rater) confirms the passing test.
6. Startup. Gas pressure, temperature rise, flame and venting checked; thermostat set up; system explained to you.

The brands we install include Daikin, Goodman, Innovair, Bosch, Fujitsu, ADP, Carrier, Bryant, Payne, York, Williams and AC PRO, and our technicians are factory trained on Daikin, Innovair, Bosch, Fujitsu, York and Honeywell equipment.

When is it time to replace a furnace?

Consider replacing a furnace when the heat exchanger is cracked, when a major repair is needed on a furnace roughly twenty years old, when repairs are becoming routine, or when you are replacing the air conditioner that shares its blower and ducts. An old furnace that still runs safely does not have to go.

• Repairs every season, or one large repair quoted on an older furnace
• Soot around the furnace, or a lazy yellow flame instead of a crisp blue one
• Rooms that never warm evenly, or a furnace that runs and runs on a cool night
• Rising gas or propane bills without a change in how you use the heat
• New booms, rattles or squeals at startup

If you are not sure, start with a repair visit. We will tell you honestly whether the furnace has years left.

Where we install furnaces

We replace furnaces throughout North County, from Fallbrook and Bonsall to San Marcos and inland Murrieta. Call (760) 728-8716 to set up an estimate, and read our guide to permits and Title 24 testing if you want to know what the paperwork involves.