# Title 24 and Existing Pools: What Triggers the New Heater Rules

- **URL:** https://adamspools.com/expertise/california-title-24-and-pool-construction/
- **Published:** 2026-08-04

California's 2025 Energy Code has governed every pool permit application filed since January 1, 2026, and for existing pool owners the question it answers is narrower than most coverage suggests. The rules do not turn on whether your pool is new or old. They turn on whether the pool currently has heating equipment in place. That distinction decides what a remodel costs. A pool that already has a working heater can generally get another gas heater. A pool that has never been heated and is now getting its first heater falls under the full requirement, which effectively means a heat pump or a solar thermal system. Both of those are common renovation scenarios, they sit inches apart in the code, and they are thousands of dollars apart in practice. Where that line falls changes the shape of the retrofit work we do on existing Bay Area pools. The Line That Matters Is Whether Heating Equipment Is Already In Place The energy code does not ban gas outright. What it does is require the pool's primary heat source to meet one of five approved ways of sizing a heating system, and neither a gas heater nor electric resistance heating qualifies under any of them. Gas is still legal, but only as supplementary or backup heat behind a compliant primary source. Energy Code Ace, the compliance program California's investor-owned utilities run under the auspices of the Public Utilities Commission, puts it plainly in its 2025 pool and spa heating fact sheet: gas and electric resistance cannot serve as the primary heating system, though either can be used for supplemental heating or combined with on-site renewable energy. One exception matters enormously to renovation work, and it turns on equipment that is already there. This existing-equipment exception covers alterations to existing pools and spas that already have heating systems or equipment in place, and it is what allows gas-for-gas replacement to continue. The exception is narrower than it sounds, and it does not reach these. What the rule coversCode sectionDoes the existing-equipment exception reach it?The heating source requirementSection 110.4(c)Yes. This is the only thing the exception applies toPiping, covers and time switchesSection 110.4(b)NoPilot lights on gas pool heatersSection 110.5No So gas-for-gas replacement on a pool that already has a heater does not trigger the new primary heating source mandate. A lot of 2025 coverage says the energy code does not apply to existing pools at all. It does. Replacing a Heater on a Pool That Already Has One This is the most common call we get, and the answer is reassuring. If your pool has a working or recently failed heater and you want another gas heater in its place, the existing-equipment exception covers you. You are not being forced onto a heat pump. The reasoning matters more than it looks, because the popular explanation is wrong in a way that can cost you at inspection. People say a heater swap is a repair, and repairs are exempt. The energy code does not define it that way. It sorts every job into four buckets, newly constructed, addition, alteration and repair, and it says outright that replacing any component or piece of equipment the code sets requirements for counts as an alteration rather than a repair. Pool heaters have requirements, so a whole-appliance heater replacement is an alteration. The practical difference is that an alteration still has to satisfy every pool and spa requirement the exception does not cover, plus the certified-equipment standards. State law also bars a continuously burning pilot light on a gas pool heater, which rules out some older replacement units outright. Where that line sits is worth confirming, because published compliance guidance treats component-level repairs to an existing heating system as outside the energy code, and it is whole-appliance replacement that lands on the alteration side. Confirm the scope with your building department rather than assuming the job carries no code obligations. Heating an Older Pool for the First Time This is the scenario the 2025 code changed most, and it is the one that gets missed. A great many Bay Area pools built in the 1960s, 1970s and 1980s were never heated at all. When a homeowner renovating one of those pools decides to add heat, that is an alteration to a pool with no existing heating equipment, so the existing-equipment exception does not reach it. The full heating source requirement applies, exactly as it would on a brand new pool. Of the five approved pathways, only some are realistic on a retrofit. PathwayWhat it requiresOn a Bay Area retrofitSolar thermalCollector surface area equal to 60 percent or more of the pool surface area for a single-family home, and 65 percent or more for multifamily and nonresidential propertiesOften impossible on an existing house with a mature tree canopy, an unfavourable roof orientation or a roof already carrying photovoltaic panelsHeat pumpSized as the primary heating system by the code's own sizing method. A supplementary heater can use any energy sourceDoes the work on the overwhelming majority of retrofitsOn-site renewableAt least 60 percent of annual heating energy from on-site renewable or recovered energyThe same practical obstacle as solar thermalSolar and heat pump combinationPairs solar with a heat pump and permits no additional supplementary heater at allNo supplementary heater of any kind is permittedApproved alternativeAn alternative system the Energy Commission's Executive Director determines uses no more energy than the othersA specialist route rather than a homeowner option Which leaves the heat pump pathway, sized as the primary heating system by the code's own method, doing the work on the overwhelming majority of retrofits. A supplementary heater on that pathway can use any energy source, so a gas heater can legitimately stay in the system as backup. There is a catch that is new in this code cycle, and it is about how the two are wired to work together. The controls have to keep the backup heater from firing whenever the heat pump alone can meet the load, and the cut-on and cut-off temperatures for the heat pump both have to be set higher than the matching temperatures for the backup heater. That is worth knowing if you already own a serviceable gas unit and are adding heat capability rather than replacing it. If you are planning a renovation on an unheated pool, decide about heat before the plans are drawn rather than after. Adding heat later converts a straightforward resurfacing project into a permitted energy-code project, and the equipment pad, the electrical run and sometimes the service panel all have to be designed for it. The Requirements That Still Reach an Existing Pool A second set of pool requirements has no alterations exception at all, so they apply whenever the component in question is part of your scope of work. Three of them come up constantly on renovation jobs. RequirementCode sectionWhat it requiresSolar-ready piping110.4(b)2At least 18 inches of horizontal or vertical pipe between the filter and the heater, or dedicated suction and return lines, or built-in connections, so that solar heating equipment can be added later without re-plumbingResidential circulation plumbing150.0(p)2A straight run of at least four pipe diameters ahead of the pump, sweep elbows rather than sharp fittings, and velocity limits of 8 feet per second on returns and 6 feet per second on suction linesOff-peak pump scheduling110.4(b)4A permanently installed time switch or similar control that can be set so the circulation pumps run only during off-peak electric demand periods The piping number changed in this code cycle. The 2022 code required 36 inches for the same purpose, so this one got easier rather than harder. If a plan set or a checklist in front of you still says 36 inches, it is written to the previous cycle. Any renovation that re-plumbs the equipment pad hits the circulation requirements, and older pools frequently do not meet them because they were built before the requirement existed. And if you are replacing pool controls as part of a remodel, the off-peak scheduling capability has to be there. What a Heat Pump Retrofit Involves on an Older Pool Electrical capacity is the item that most often turns a straightforward heat pump swap into a bigger job. Published manufacturer specifications for common residential units in the 90,000 to 140,000 BTU range show: Minimum circuit ampacity of roughly 38 to 43 amps 208 to 230 volts, single phase A dedicated 50 to 60 amp breaker Every unit we see in that capacity class is 208 to 240 volt single phase, and manufacturers specify a supply voltage range that a marginal service can fall below, so we check the supply against the spec sheet before the unit is ordered. Whether that requires a service upgrade is a calculation, not a rule of thumb. The common claim that any pool heat pump needs a 200 amp panel is not true. What governs is a load calculation on the existing house. Existing serviceTypical outcomeA lightly loaded 100 or 125 amp panelSometimes passesA 200 amp panel already carrying an EV charger, an electric range, a heat pump water heater and central air conditioningSometimes does not Load management devices can occasionally avoid an upgrade. This gets checked before we quote, not after. Expect a separate electrical permit regardless of how the building permit is packaged. Trade permits for electrical, plumbing and mechanical work are not waivable in the jurisdictions we work in, and pool wiring and equipotential bonding are governed by the electrical code, which itself moved to its 2025 edition on January 1, 2026. Set expectations on performance too, because heat pumps behave nothing like the gas heater they replace. Output falls as air temperature falls. Output at 50 degrees ambient falls far enough below rated capacity that a unit sized on its rating alone will disappoint, and manufacturers note that operation stops near 50 degrees. A heat pump also heats slowly. The code's own sizing basis allows up to 17.5 hours to achieve a 10 degree rise, which means the equipment is designed to hold a set temperature continuously rather than to heat a cold pool for the weekend. Homeowners who run a heat pump the way they ran a gas heater are the ones who end up disappointed. There is more on the equipment side of this decision in why we partnered with Madimack for our pool heat pumps, and the full range of what goes on an equipment pad is on our pool equipment page. Covers Are Not Optional on a Heated Pool The cover rule is one sentence long and it catches people who assumed going electric would simplify things. An outdoor pool or spa with electric or gas heating equipment has to be installed with a pool cover. There is no exception clause attached to it. A heat pump is electric heating equipment, so switching from gas to a heat pump does not get you out of the cover requirement. A solar-only pool is never triggered by the rule, because it has neither electric nor gas heating equipment. That is a consequence of the wording rather than an exemption, and it is a narrow case in practice. The requirement attaches at installation, so it is not retroactive onto a pool nobody is touching. Replacing the cover on an existing gas-heated or electric-heated pool does bring it back into scope. Since a cover is required anyway, it is worth choosing one that earns its keep rather than treating it as a compliance item. The trade-offs are in our guide to automatic pool covers for inground pools. Spas Have Their Own Exceptions Spa projects on existing properties get more relief than pools do, and it is easy to miss because the exceptions are buried in the same part of the code. SituationHow the heating rule treats itPortable electric spasRegulated under a separate appliance standard, not the pool heating rulePermanent spas installed in existing buildings where gas is availableHave their own exceptionPermanent spas on properties without adequate Solar Access Roof AreaHave their own exceptionA solar-only system with no backup heaterOutside the sizing pathways, since there is nothing to size against If your renovation includes adding a spa to an existing home, that is worth checking before anyone assumes a heat pump is mandatory. The answer is frequently no. Two Rules People Attribute to Title 24 That Are Not in It Smart controls and demand response are the first. A lot of 2025 and 2026 coverage states that the energy code now requires new pool control systems to be capable of demand response so they can communicate with the grid. That requirement is real, but it is not in the energy code at all. It sits in the state's separate appliance standards, under the Flexible Demand Appliance Standards, and it applies to newly installed and replacement pool controls manufactured on or after September 29, 2025. The pool part of the energy code has two control requirements of its own, and neither one is a demand response mandate: the off-peak time switch described above, and the rule new in this code cycle that governs how a heat pump and its backup heater are sequenced. The distinction matters when you are reading a spec sheet and trying to work out which document to check compliance against. A retroactive obligation is the second. Nothing in the 2025 energy code requires you to replace a functioning heater on a pool nobody is renovating. Which edition applies to your project is set by the date your permit application is filed, and state law says only the standards in force on that date can be applied to your plans and your construction. A pool sitting untouched is not a project and has no application date. There Are No Pool Heat Pump Rebates Right Now Homeowners keep asking, and the answer has changed. As of August 2026 we can find no California utility, state or federal programme that rebates a swimming pool heat pump. ProgrammeWhat it coversWhere it leaves a pool heat pumpTECH Clean CaliforniaSpace conditioning and domestic water heating rather than pool equipmentThe programme most people have heard of, and its single-family reservations have closedFederal residential energy creditsThe two home energy tax creditsEnded for property placed in service and expenditures made after December 31, 2025, and the clean energy credit had always excluded expenditures allocable to a swimming pool or hot tub anywaySoCalGas pool heater rebateReplacing an existing gas heater with another gas unitThe only pool heater rebate we could identify anywhere in the state. Outside our service area, and a gas programme rather than an electrification incentive Rebate programmes open and close on their own schedules, so this is worth re-checking at the point you commit. What it means today is that a heat pump retrofit should be budgeted at its full installed cost with no incentive assumed. Deciding What to Do With an Aging Gas Heater ChoiceChoose it whenAnother gas heaterThe pool already has a heater, the unit is at end of life, and you want the lowest installed cost and the fastest recovery from coldA heat pumpYou use the pool through the shoulder seasons and want to hold a temperature rather than heat on demand, your operating cost matters more than your installed cost, or you are opening the equipment pad anyway during a larger renovation and the electrical capacity is already there The existing-equipment exception protects the gas-for-gas choice, and no amount of code reading changes the fact that gas heats a pool faster. The heat pump retrofit is easiest to absorb when it happens alongside other work rather than as a standalone job. You do not get the choice if the pool has never been heated. In that case the full heating source requirement applies, the heat pump pathway is realistically the only viable one, and the decision moves from which heater to how the electrical service and equipment pad get designed to carry it. Either way, decide it during design. A heating decision made after the plans are approved is the single most expensive change order on a pool renovation, because it can reopen the plumbing layout, the equipment pad and the electrical scope at once. If you are planning work on an existing pool and want to know which side of that line you fall on, that is a short conversation. You can see what a renovation typically costs in our 2026 Bay Area resurfacing cost breakdown, or get in touch and we will tell you what your pool's history means for your permit. For Your Contractor and the Permit Desk What it governsWhere it livesThe California Energy Code itselfTitle 24, Part 6Heating source sizing, the five pathwaysSection 110.4(c)The existing-equipment exception for alterationsException 2 to Section 110.4(c)Piping, covers and time switches, no alterations exceptionSection 110.4(b)Solar-ready piping, 18 inchesSection 110.4(b)2Pool cover on an outdoor heated pool or spaSection 110.4(b)3Permanently installed off-peak time switchSection 110.4(b)4Controls for a heat pump with a supplementary heaterSection 110.4(d)Continuously burning pilot lights prohibitedSection 110.5Residential pool circulation plumbingSection 150.0(p)2Solar Access Roof Area, as used in the spa exceptionSection 150.1(c)14Heat pump pool heater sizing methodReference Joint Appendix JA16.3Flexible Demand Appliance Standards for pool controls, units manufactured on or after September 29, 2025Title 20Pool wiring and equipotential bondingArticle 680, California Electrical CodeCode edition is fixed by the permit application dateHealth and Safety Code section 18938.5Federal residential energy credits, ended after December 31, 2025Internal Revenue Code sections 25C and 25D, as amended by Public Law 119-21 The 2025 California Energy Code is the edition in force as of August 2026. The Energy Commission publishes the current standards on its 2025 Building Energy Efficiency Standards page, and code editions change on a three-year cycle.