Heat-Pump Water Heaters and 2025 Title 24: Inputs, Air and Forms

02Begin with new construction versus an existing-system alteration

The CEC’s 2025 Single-Family Compliance Manual distinguishes mandatory measures, prescriptive options and performance treatment. For new single-family construction, its water-heating chapter describes prescriptive heat-pump or qualifying solar-water-heating approaches, with specific conditions and exceptions. That is not the same as a claim that every existing gas water heater must be replaced with a heat pump.

An alteration needs the appropriate existing-building review. The CEC publishes replacement-water-heater FAQs describing several allowed pathways and their conditions. Existing fuel, proposed type, location, distribution and related work matter. Do not transfer a new-home prescriptive package to every replacement without checking §150.2.

An addition may involve a new water heater or connection to an existing system. Identify which spaces and units it serves and how distribution changes. “Keep the existing tank” is not enough information if the addition materially changes the proposed system or supported model assumptions.

CEC single-family water-heater alteration guidanceWater-heater replacement decision guide

03Mandatory backup heat: compare the right temperatures

Chapter 5 explains §110.3(c)7A: when the heat-pump water heater’s inlet air is outdoor air, backup heat is required if its compressor cutout temperature is above the local Heating Winter Median of Extremes. The manual’s detailed discussion also addresses unconditioned inlet air. Review the actual air arrangement and manufacturer information with the responsible designer.

Do not invent a citywide climate temperature or use a thermostat setting as the compressor cutout. Obtain the manufacturer’s minimum compressor operating temperature and compare it with the applicable JA2 location data as directed by the provision. Equality and other boundary cases should be checked against the adopted text rather than resolved from a summary.

Backup heat may be internal or external under the cited guidance; an integrated unit can have built-in electric-resistance backup. The relevant question is whether the actual system provides the required backup, not whether the brochure uses the word “hybrid.” The equipment and controls must be documented consistently.

CEC Chapter 5 backup-heat explanation and examplesCEC reference appendices, including JA2

04Ventilation: the heat source is the surrounding air

A heat-pump water heater extracts heat from air. If the air’s thermal resource is not replenished, the surrounding temperature can fall and operation can be affected. The 2025 §110.3(c)7B provisions therefore address ventilation, not just tank efficiency.

The CEC describes several arrangements: an unducted unit in a sufficiently large room, an unducted unit in a smaller ventilated room, a ducted installation or a supported manufacturer method. Those are categories for design review, not instructions that every closet is suitable or that cutting one arbitrary opening is enough.

Have the responsible designer and installer determine clearances, air paths, room conditions and manufacturer requirements. Identify whether intake or exhaust is ducted and where it connects. Our energy documents do not size ventilation openings, design ducts or certify a safe plumbing/electrical installation.

05The intake checklist that prevents unsupported model inputs

Prepare a coordinated equipment record rather than a screenshot of a retail listing. If a product or location is provisional, identify the open decision and its owner.

• +Equipment: manufacturer, model, tank/storage capacity, rated efficiency and applicable performance data; identify an integrated or split arrangement.
• +Air and backup: installation room, available air arrangement, ducted intake/exhaust if proposed, compressor cutout information and backup-heating provision.
• +Installation coordination: electrical supply as designed by the responsible professional, condensate route, service access and supported location details.
• +Distribution: served units and fixtures, new versus retained piping, insulation, recirculation and any compact-distribution or recovery feature claimed.
• +Permit context: AHJ-recorded application date, new/addition/alteration scope, existing equipment and any prior energy documents or correction comments.

06JA13 and forms: identify the claim before naming a certificate

Joint Appendix JA13 provides qualification requirements relevant to heat-pump water-heating systems where the applicable compliance approach invokes them. It is not a promise that any product sold as a heat pump qualifies for every modeled credit or installation pathway. Check the current appendix, approved calculation method and selected equipment evidence.

For an applicable single-family project, CF1R captures design compliance assumptions. Installer CF2R records and required ECC verification records address later responsibilities where measures require them. The current catalog and instructions determine the actual documents; do not copy a suffix from an unrelated heat-pump job.

ECC is the current 2025-cycle field-verification framing. HERS can remain on older-cycle plans or registry records, and should not be erased from a valid earlier project without review. Design preparation is not an assertion that Title 24 Lab operates a registry, performs testing or signs an installer’s certificate.

HERS-to-ECC transition explainedCF1R, CF2R and CF3R responsibilities

07Illustrative example: a model selection with a missing air-path detail

ILLUSTRATIVE ONLY: an owner selects a heat-pump water heater for a garage installation during a remodel. The initial packet gives a model number but no inlet-air arrangement, compressor cutout data or condensate detail. No local temperature or compliant installation is assumed.

The preparer requests the manufacturer information and the responsible designer’s location/air strategy. If the applicable outdoor-air backup condition is present, the team documents the required backup rather than guessing from tank capacity. The installer also coordinates ventilation and distribution details outside the report preparer’s role.

Only then can the design package describe the actual selected system. If the owner later relocates it to a small closet, the team must review the air arrangement again; an earlier report does not approve every installation location. A clear intake packet is more valuable than a rushed final model using a convenient default.

08Coordinate costs and scope without selling unrelated services

Use the published residential/commercial report tiers for the design-document scope. No equipment price, installer fee, incentive amount or ECC tester charge is quoted here. Ask the responsible providers about their own services rather than assuming an energy-report price includes the appliance or construction.

CALGreen Part 11, electrical and plumbing requirements can coexist with Part 6. They are not all the same deliverable, and Title 24 Lab does not prepare CALGreen documentation. Upload the plans and identify which energy record is requested so the scope can be confirmed before production.

Part 6 versus CALGreenPublished pricing and exclusionsUpload water-heating plans

09Six heat-pump water-heater questions

10Turn the question into a scoped documentation request

Title 24 Lab is a provisional brand for design-phase energy-document preparation. Field testing, acceptance testing, registry fees, CALGreen documentation and AHJ fees are excluded. This is educational information, not legal advice; confirm the application date, classification and requirements with the AHJ. Review the shared published pricing, then upload the current plans and identify unresolved inputs. Submission is not payment, production acceptance or permit approval.

See published residential and commercial pricingWhat to send with the plansGet a quote / upload plans privately