What HVAC systems are prohibited in California cities with all-electric mandates?

In California cities that have adopted all-electric "reach codes," gas-burning HVAC and appliances are prohibited in new ADU construction — meaning no gas furnaces, no gas water heaters, and no gas piping for those systems. The required alternative is all-electric equipment, most commonly a mini-split or central heat pump paired with a heat pump water heater.

What an all-electric mandate prohibits

Dozens of California cities — including Los Angeles, San Jose, San Francisco, Oakland, Berkeley, Sacramento, and many others — have adopted local ordinances that restrict or prohibit natural-gas infrastructure in new buildings. Where these reach codes apply to ADUs, the mechanical and plumbing plans cannot show:

• Gas furnaces or gas-fired space heaters.
• Gas water heaters, including gas tankless units.
• Gas-fired ranges/cooktops (where the ordinance extends to cooking).
• The gas piping, meters, and vent/flue systems serving those appliances.

What replaces them

Under an all-electric mandate, the compliant ADU mechanical and plumbing design centers on:

• Heat pump space conditioning — a ductless mini-split or a ducted heat pump for heating and cooling.
• Heat pump water heater (HPWH) — the favored electric water heating method under the 2025 energy code, with electric tankless allowed in some space-constrained cases.
• Induction or electric cooking where gas cooktops are restricted.
• Electric-resistance backup or supplemental heat only where engineering justifies it.

An important nuance: "prohibited" depends on your address

There is no single statewide gas ban. Whether a system is prohibited depends entirely on whether your jurisdiction has adopted an all-electric ordinance and how that ordinance is written — some apply only to new detached construction, some exempt certain appliances, and some are structured as energy-code amendments rather than outright bans. Because these reach codes change frequently and have been the subject of ongoing legal developments, you must confirm the current rule with your local building department before finalizing any mechanical or plumbing design.

Even in cities that still permit gas, the 2025 California Energy Code strongly favors heat pumps. Many owners choose all-electric voluntarily to future-proof against expanding restrictions and to simplify Title 24 compliance.

All-electric design checklist

1. Confirm whether your city has an active all-electric reach code, and whether it applies to your ADU type.
2. If it applies, remove all gas appliances and gas piping from the plan set.
3. Specify a heat pump for space conditioning and a HPWH (or compliant electric tankless) for hot water.
4. Verify the electrical panel is sized for the higher all-electric load (heat pump, HPWH, induction, EV-ready).
5. Coordinate the equipment selections with the Title 24 compliance documents so they match.

All-electric ordinances and exemptions vary by jurisdiction and change frequently — confirm current details before you design. Our mechanical, electrical, and plumbing plans are built around your city's requirements, and the Full MEP package keeps all three disciplines coordinated. Order here when ready.