Having a swimming pool in California often means you want to extend your swimming season and keep water comfortable without running up the bill. The right heater makes that possible. This updated guide (October 2025) explains the main heater types, the latest California rules, and a clear process to choose what fits your home, budget, and climate.

Types of Pool Heaters (Quick Overview)

Solar: Circulates water through roof or ground-mounted solar collectors. Very low operating cost; performance depends on sun exposure.
Gas (natural gas or propane): Burns fuel to heat water quickly. Higher running cost and emissions; California rules are tightening for new primary heaters.
Electric resistance: Uses heating elements. Simple and compact, but typically the highest operating cost; best for small/above-ground pools with light use.
Heat pump: Moves heat from ambient air into the water using electricity. High efficiency and lower emissions; output falls during colder weather.

Comparison Table (Efficiency, Cost, and Fit for CA)

Heater Type	How It Heats	Upfront Cost	Operating Cost	Heating Speed	Best Fit in California
Solar	Sun via collectors	Medium–High	Very Low	Moderate (weather-dependent)	Sunny areas (SoCal, Inland valleys) with good roof/yard exposure
Gas	Burns natural gas/propane	Low–Medium	High (fuel + service)	Fastest	On-demand/occasional use; verify local emission and code limits
Electric resistance	Heating elements	Low–Medium	Highest per heat unit	Moderate	Small/above-ground pools, light use
Heat pump	Moves heat from air to water	Medium–High	Low–Medium (very efficient)	Moderate–Fast in mild temps	Most CA regions with regular use; strong cost-to-comfort balance

California Rules You Should Know

California’s Building Energy Efficiency Standards (Title 24, Part 6) emphasize high-efficiency, low-emission pool and spa heating. In many new builds and major remodels, the primary heater is expected to be solar thermal, a heat pump, or site-recovered energy. Local air-quality districts enforce low-NOx limits on gas units, and federal efficiency standards for pool heaters continue to tighten. Existing gas heaters can usually stay in service, but future replacements may face stricter requirements. Pool covers are often required or strongly encouraged to reduce energy use. Always confirm the latest details with your city/county and a licensed contractor before you buy.

How to Choose — A California-Focused Process

Match to your climate and use: In sunny zones (San Diego, Orange County, Inland Empire), solar and heat pumps work well for frequent swimmers. For occasional, on-demand use, gas heats fastest, but check code limits for new primary systems.
Balance first cost vs. lifetime cost: Solar and heat pumps cost more to install but run far cheaper. Gas can be cheaper to install, yet fuel and maintenance add up and rules are tightening.
Evaluate your site: Sun exposure, roof area/structure, shade, wind, and lot layout all matter. Shaded sites favor heat pumps; wide, sunny roofs favor solar.
Right-size the system: Larger pools need higher capacity (BTU/tonnage). Undersizing causes slow warm-ups; oversizing wastes money.
Future-proof: Choose equipment that remains compliant as standards evolve. Ask about solar-ready plumbing, smart controls, and possible utility incentives.
Use a licensed contractor: Proper design, hydraulics, gas/electrical work, and permitting protect safety, performance, insurance conversations, and resale value.

Efficiency Tips That Pay Back

Use a pool cover: The single biggest heat-loss reducer; it makes any heater more effective and lowers bills.
Improve circulation: Clean filters and correct pump speeds improve heat transfer and cut run time.
Mind placement: Keep heat pumps clear for airflow; keep solar collectors clean and well-oriented.
Service annually: Burners/heat exchangers (gas), refrigerant/coils (heat pumps), and solar flow/valves all need periodic checks.
Track runtime and temperature: Use built-in controls or timers to avoid unnecessary heating overnight or on hot days.

What This Means for California Homeowners

If you are installing a new heater, plan for a solar or heat-pump primary system to stay efficient, reduce emissions, and align with code. If you already own a gas heater, you can usually keep it, but budgeting for a future transition is sensible. Choosing compliant, well-installed equipment reduces retrofit risk, supports property value, and helps keep day-to-day costs predictable.

FAQ

Can I still install a gas pool heater?
Often yes for replacements or as supplemental heat. For new primary heaters, rules are moving toward solar or heat pumps in many scenarios. Check your local permitting office before buying.

Are electric resistance heaters a good idea?
They are acceptable for small or above-ground pools with light use, but operating costs are higher. For regular swimming, heat pumps or solar usually cost less to run in California.

My yard is shaded — does that rule out solar?
Not completely, but it reduces output. Heat pumps are usually the better fit for shaded sites or where roof space is limited.

Will a cover really make a difference?
Yes. Covers dramatically cut evaporation and nightly heat loss, improving comfort and lowering energy use regardless of heater type.

How to choose the right pool heater