Code Readiness Data Brief: Laboratory Testing of Residential Heat Pump Water Heater Performance: Impact of Airflow and Space Configuration

The current California Building Standards Code, Title 24, does not include minimum ventilation requirements for residential heat pump water heaters (HPWH). Building owners across California are installing HPWHs in small closets without adequate ventilation, leading to high electric resistance backup use, often during peak demand periods, yielding poor overall equipment performance, high utility bills, and often leading to spikes in demand on the power grid. The Code Readiness project team (Project Team) was interested in exploring this phenomenon further and initiated a laboratory test project in fall 2022. This project aimed to understand the impact of airflow and installation location on HPWH performance, outline HPWH installation best practices, and identify opportunities for Title 24 code development. The Project Team tested three water heater products under different intake and exhaust ventilation and temperature configurations to replicate typical HPWH installations in new and existing residential and multifamily buildings.

This data brief presents the laboratory test data collected under this project, and the key research methods used. A comprehensive project report will be published later in 2023.

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Heat pump water heater, HPWH, ventilation, airflow, closet, small space, COP, performance, laboratory testing, lab testing, retrofit, new construction, HPWH installation, data brief