Measure Overview
This measure proposes to create a prescriptive pathway to require Return to Primary configuration for split Heat Pump Water Heater (HPWH) systems with recirculation in nonresidential buildings. This would include an alternative pathway for products on the Northwest Energy Efficiency Alliance (NEEA) Tier 3 qualified product list, including standardized configurations and manufacturer’s requirements. The proposed measure would update JA14 – Qualification Requirements for Hot Water Systems to include new requirements for the design, installation, equipment and control start up, and performance data reporting (Coefficient of Performance (COP), Defrost derate, Input power, Output Capacity, Refrigerant type, etc.).
This proposed measure would require additions to the compliance forms, changes to the compliance software, and new plan check and building inspector activities.
Table 1 summarizes the scope of the proposed code change. This requirement would apply to additions and alterations with a proposed water heater replacement with split HPWHs. The proposed measure does not require installation of HPWHs.
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Scope of Proposed Code Change
| Building Type(s) | Construction Type(s) | Type of Change | Updates to Compliance Software | Third Party Verification |
| Nonresidential | New construction, additions, alterations | Prescriptive | Update existing feature, add new feature | No changes to third party verification |
Justification for Proposed Change
The current nonresidential prescriptive requirements for water heating do not include requirements specific to HPWH performance despite the increasing use of HPWH in nonresidential applications. Pending air quality rules by the South Coast Air Quality Management District (SCAQMD) and the Bay Area Air Quality Management District (BAAQMD) will require HPWH installations for most buildings in California, since these two air quality districts cover roughly 49% of the sq ft. This measure, focused on nonresidential applications, draws on lessons learned from the development of multifamily requirements, including recent research (Brooks, Neal and Young 2024) (PG&E, SCE 2024) that indicates that Return to Primary is advantageous over swing tank configuration in many cases.
By eliminating the electric resistance (ER) swing tank, the proposed change would reduce electricity capacity requirements, peak demand, and grid impact, and improve grid reliability. The compact design of the Return to Primary configuration would reduce installation costs, space requirements, and the complexity of installation and start-up. Return to Primary configuration has a higher system (COP) than the temperature maintenance heater in series (TMHS) configuration, which would achieve operational savings. Proposed start-up requirements also ensure long-term savings for split HPWH systems with recirculation.
Relevant Documents
Round One Utility-Sponsored Stakeholder Meeting Materials
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The Statewide CASE Team values input from all stakeholders engaged in the Title 24, Part 6 code change process. We encourage the open exchange of code change comments and concerns.