Field Measurement of Central CO2 Heat Pump Water Heater for Multifamily Retrofit

Banks, Adria; Grist, Colin; Heller, Jonathan; Lim, Hyunwoo

doi:10.3390/su14138048

Field Measurement of Central CO2 Heat Pump Water Heater for Multifamily Retrofit

Journal Article · Fri Jul 01 00:00:00 EDT 2022 · Sustainability (Basel)

DOI:https://doi.org/10.3390/su14138048· OSTI ID:1874824

Banks, Adria; Grist, Colin; Heller, Jonathan;

Domestic hot water heating of multifamily buildings accounts for a substantial portion of the energy load of existing buildings. This load is made up of both the energy required to produce hot water and the energy needed to maintain the temperature of the heated water within a building’s distribution piping so that heat can be promptly delivered to building occupants as needed. Properly designed heat pump water heater (HPWH) systems have the ability to improve efficiency in both water heating and temperature control operations. Further, CO2 heat pump technology reflects a shift away from traditional refrigerants and toward refrigerants with low global warming potential (GWP). In this paper’s case study, a design consisting of multiple CO2 heat pump water heaters (commonly used in single-family homes) with a novel “swing tank” was proposed to meet the demand for domestic hot water heating and recirculation loop temperature maintenance. The proposed design was applied to the retrofit of a 60-unit, low-rise, multi-family building located in the Pacific Northwest of the United States. The purpose of this paper is to verify the performance of the system including the proposed “swing tank” in a centralized SHW system using CO2 HPWH. It also provides practical information and lessons learned from the retrofit project. Long-term monitoring data showed that the system had a coefficient of performance (COP) of three or greater and provided an average of 20 gallons of hot water per day per apartment. The results of this work indicate that residential-scale CO2 HPWH equipment and a “swing tank” design can efficiently provide domestic hot water heating and temperature maintenance for mid-sized multifamily buildings.

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Sponsoring Organization:: USDOE

OSTI ID:: 1874824

Journal Information:: Sustainability (Basel), Journal Name: Sustainability (Basel) Journal Issue: 13 Vol. 14; ISSN SUSTDE; ISSN 2071-1050

Publisher:: MDPI AGCopyright Statement

Country of Publication:: Switzerland

Language:: English

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