You’re replacing your heater and the quote sheet lists two options: a heat pump or a gas furnace. One runs on electricity, one on gas, and the price difference on paper doesn’t tell you which one costs less to own. In San Diego, the answer isn’t obvious — and it’s worth running the actual numbers before you commit.
How San Diego’s mild winters change the math
Most heat pump comparisons are written for Chicago or Minneapolis, where winter temps drop into single digits. In those climates, heat pumps struggle to extract heat from frigid outdoor air and their efficiency drops fast. The math there often favors gas.
San Diego is a different story. Our “cold” months run roughly from November through February, with average lows in the upper 40s in inland neighborhoods like El Cajon and Santee, and mid-50s closer to the coast. Even on the coldest nights in Alpine or Ramona, we rarely dip below 30°F.
That matters because heat pump efficiency is measured by coefficient of performance (COP) — how many units of heat you get per unit of electricity you put in. At 47°F outdoor air, a modern heat pump delivers a COP of 3.0 to 4.0. That means 3 to 4 BTUs of heat for every 1 BTU of electricity consumed. A gas furnace, even a 96% AFUE model, converts energy at 0.96 BTUs per BTU of gas input — by definition, it can never exceed 1.0.
San Diego’s mild winters keep heat pumps operating in their sweet spot almost all season. You get the efficiency multiplier nearly every time the system runs. That’s the foundation of why heat pumps tend to win the annual operating cost race here — but the actual margin depends on what SDG&E charges you.
We covered the broader heat pump versus air conditioner question in our earlier post on heat pump vs AC in San Diego, so this piece focuses specifically on the heating fuel cost comparison.
Operating cost comparison using actual SDG&E rates
SDG&E uses tiered electricity pricing. As of early 2026, residential customers on the standard DR-SES rate pay roughly $0.35/kWh in Tier 1 and $0.48/kWh in Tier 2. If you’re on a time-of-use (TOU) plan, super-off-peak rates drop to around $0.25/kWh overnight.
Natural gas runs approximately $2.20 per therm on SDG&E’s current residential schedule (this fluctuates — check your bill for the exact delivery and commodity charges combined).
Now let’s put those numbers to work.
Heat pump heating cost estimate
A 3-ton heat pump with a heating seasonal performance factor (HSPF2) of 9.0 uses about 1 kWh of electricity to deliver roughly 9,000 BTUs of heat. A typical San Diego home needs around 15–20 million BTUs of heat per year to stay comfortable through winter. Call it 17 million BTUs.
At HSPF2 9.0, that’s roughly 1,890 kWh consumed annually for heating. At a blended SDG&E rate of $0.38/kWh (mixing Tier 1 and Tier 2 usage), that’s about $718 per heating season.
Gas furnace heating cost estimate
A 96% AFUE gas furnace delivering 17 million BTUs needs about 17.7 million BTUs of gas input. One therm equals 100,000 BTUs, so that’s roughly 177 therms. At $2.20/therm, that’s about $389 per heating season.
Wait — gas wins? On fuel cost alone, yes, gas is cheaper right now in San Diego. SDG&E’s electricity rates are among the highest in the country, and that narrows the heat pump’s efficiency advantage considerably.
But here’s what that comparison misses: heat pumps also cover your cooling load. If you’re replacing a furnace-plus-AC setup, the heat pump replaces both. Your air conditioning electricity cost — often $400–$700 per summer in San Diego — factors into the total system economics. On a combined annual basis, a heat pump system typically beats a furnace-plus-separate-AC setup by $200–$500 per year depending on your home’s size and insulation.
The California Energy Commission publishes updated fuel cost modeling tools if you want to run your own numbers with your specific home’s load.
Where gas furnaces still make sense
Gas furnaces aren’t obsolete in San Diego. There are real scenarios where recommending one is the honest answer.
No existing central AC. If your home is heated-only — older construction with a wall furnace and no ducts for cooling — swapping to a gas furnace costs less upfront and avoids a full ductwork installation. A furnace repair or replacement on an existing system can be straightforward.
All-electric panel is already maxed out. Heat pumps pull significant amperage. A 3-ton unit needs a dedicated 240V/30–40A circuit. If your panel is a 100-amp service already running near capacity, adding a heat pump may require a panel upgrade ($2,000–$4,500). A gas furnace sidesteps that entirely.
Homes in high-altitude East County. Places like Pine Valley or Mount Laguna do see sustained cold snaps below 30°F. Standard heat pumps lose efficiency there. You’d want a cold-climate model (rated to -13°F) or a hybrid system — which we cover next.
Shorter ownership horizon. If you’re selling in two or three years, the payback timeline on a premium heat pump install may not close before you hand over the keys. A straightforward furnace replacement can make financial sense in that window.
Hybrid dual-fuel: the underrated middle option
A hybrid dual-fuel system pairs a heat pump with a gas furnace backup. The heat pump handles the load whenever outdoor temps stay above a set “balance point” — usually around 35–40°F. When it drops below that, the furnace takes over automatically.
In San Diego proper, the furnace almost never kicks in. In Escondido, Julian, or Fallbrook it fires a handful of nights per year. Either way, you get heat pump efficiency through 95%+ of the heating season while keeping gas as insurance against extreme cold.
The cost premium over a standalone furnace is real — typically $1,500–$2,500 more installed — but the system qualifies for the same rebates as a full heat pump. SDG&E and the state both offer incentives for heat pump equipment. See our full breakdown of SDG&E heat pump rebates for 2026 for current numbers, which can cut that premium significantly.
Hybrid systems are also a smart answer for homes with an existing gas furnace in good shape. You add a heat pump on top rather than scrapping working equipment. That’s often the most cost-efficient path to lower operating costs.
One thing to budget for if you’re retrofitting gas into a home that didn’t previously have it: gas line extension and hookup costs in San Diego typically run $500–$2,000 depending on distance from the meter to the air handler. That’s not a number most online comparisons mention, but it belongs in any honest quote.
What an honest install quote should include
Whether you choose a heat pump, a gas furnace, or a hybrid, the quote you get from any contractor should cover a specific set of items. Vague line items are a flag.
Equipment specs with model numbers. Not just “3-ton heat pump.” The model number lets you verify the SEER2 and HSPF2 ratings yourself on the AHRI directory.
Electrical work, if any. Will you need a new circuit, panel upgrade, or subpanel? That cost belongs in the estimate, not as a surprise on day two of installation.
Gas line work, if applicable. Same principle. If the furnace needs a new or extended gas line, get that scoped before you sign.
Permit and inspection fees. In San Diego County, HVAC replacements require a permit. Any contractor who tells you permits aren’t necessary for a straight swap is either wrong or cutting corners. You can verify a contractor’s license status at the CSLB license lookup tool before you hire.
Rebate handling. Will the contractor file SDG&E and IRA rebate paperwork, or are you on your own? Some companies handle it end to end; others hand you a form and wish you luck. Know upfront which you’re getting.
Warranty terms separated by labor and parts. Manufacturer equipment warranties don’t cover installation defects. Labor warranty should be explicitly stated — typically one to two years from a reputable shop.
If a quote doesn’t include those line items, ask for them in writing. If the contractor pushes back, that’s information too.
When to call us
Choosing between a heat pump, gas furnace, or hybrid system involves load calculations, panel capacity checks, and ductwork assessment — work that requires a licensed HVAC contractor, not just a cost calculator. If your existing system is failing or you want a side-by-side quote that accounts for your home’s actual conditions, we can walk through it with you. Call us at (858) 925-5546 for a same-day estimate.