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BPA is looking at innovative heat pump system designs for water heating in commercial buildings. Air‐to‐water heat pumps can produce domestic hot water at nearly three times the efficiency than electric resistance systems. They also have a side benefit of cooling and as a result the best applications are in facilities that need both domestic hot water and space cooling. Water-to-water heat pumps can produce domestic hot water with even higher efficiencies (COPs of 5 or 6) than air-to-water heat pumps but they don’t have the added value of space cooling, so care should be taken when planning for best system. In addition, employing a CO2-refrigerant system promises to increase performance over a wide range of temperatures, compared to heat pumps using a standard refrigerant. Unlike residential or small commercial heat pump water heaters (HPWH) don’t have an integrated storage tank and large scale HPWHs are offered only by a few manufacturers, including Colmac and Nyle.  Suitable applications include facilities (ie. restaurants, hospitals, dorms, multifamily, etc.) that have total daily domestic hot water consumption of 500 gallons per day or more.

BPA has funded or is currently funding field tests of central heat pumps in buildings where heat from underground garage exhaust systems, refrigeration condensers, mechanical rooms and waste water is used to heat domestic water. We are funding additional research on methods to reduce those distribution system losses. 

​ET Projects

​Field Test of High Volume Heat Pump Water Heaters

Air-to-water heat pumps can produce domestic hot water can produce domestic hot water at nearly three times the efficiency of electric resistance systems. They also have a side benefit of cooling and as a result the best applications are in facilities that need both domestic hot water and space cooling. Unlike residential or small commercial heat pump water heaters (HPWH) don’t have an integrated storage tank and high volume HPWHs are offered only by a few manufacturers, including Colmac and Nyle. Suitable applications include facilities (ie. restaurants, hospitals, dorms, multifamily, etc.) that have total daily domestic hot water consumption of 500 gallons per day or more.
Water-to-water heat pumps can produce domestic hot water with even higher efficiencies than air-to-water heat pumps but they don’t have the added value of space cooling, so care should be taken when planning for best system. 
 
This ET Field Test could fully fund up to 5 High Volume Heat Pump Water Heaters, replacing retrofitting electric resistance water heaters with total daily domestic hot water consumption of 500 gallons per day or more, with the intent of informing a region-wide offering.

Participation Details

​Please consider participating in this ET Field Test and help fill the pipeline with a new conservation measure. Your participation and feedback is essential to developing technologies and future BPA program offerings.
Interested BPA customer utilities are invited to contact Erik Boyer at ebboyer@bpa.gov, 509-822-4586 for more information.
 

​Waste Water Heat Pump Design and Pilot Study

Abstract
Ecotope, in partnership with Vulcan Real Estate, and Seattle City Light, plans to design, pilot, and verify, a heat pump water heating system for large multifamily buildings using the building sewage as a heat source. The waste water heat pump (WWHP) will recover waste heat streams from the building and heat water for domestic use at extremely high performance levels. The system will be built in a large multifamily building with approximately 400 apartment units.
The equipment under study solves the issue of increasing the space-heating load of residences served by integrated heat pump water heaters. Using CO2 refrigerant technology promises to provide cost-effective high performance over a wide range of temperatures, representing a significant increase in performance over existing heat pump water heater technology.
To develop the WWHP system, Ecotope and partners will conduct the project in three parts:
1) Feasibility research with design concept and Building Energy Flow Model;
2) Full system design for building installation and supporting calculations for incentive funding; and
3) Pilot construction and installation; measurement and verification; and project reporting.
 
Project Team
BPA: Mira Vowles
Ecotope
Vulcan Real Estate
Seattle City Light
 
Timeline
2015 – 2018
 
Reports

​Field Test of Domestic Hot Water Recirculation System in Multifamily Residential Buildings 

Abstract
BPA funded a field test for a central heat pump water heating system providing domestic hot water to residents in a multifamily building. The results of this project have been good, with the heat pump saving a significant amount of energy compared to traditional electric resistance systems. However, the project results identified that hot water recirculation systems can reduce overall system efficiency by 30 to 40 percent. The distribution systems (hot water storage tanks, distribution piping, and circulation pumping systems) all contribute to losses and are important to understanding energy use by any central system. Thus BPA is continuing investigation to quantify the energy losses associated with typical hot water distribution systems and testing possible solutions with the intent to significantly improve distribution efficiency. This project should be completed in the latter half of 2017.
Project Team
BPA: Robert Weber
 
Timeline
2016 – 2017
 

​Field Test of Central Heat Pumps in Multi-family Residential Buildings

Abstract
For several decades, electric resistance technologies has been the predominant choice for space heating and domestic water heating in multifamily buildings in the Pacific Northwest. Reverse-cycle chillers, which use more efficient air-to-water heat pump technology, may meet these same needs with one-third as much electricity. Although reverse-cycle chillers are commonly used in warmer climates, this technology has limitations in Pacific Northwest due to colder outside air temperatures in the winter. In this study, BPA tested the performance of reverse-cycle chillers in below-grade parking garages in Seattle, Washington, where ambient air may be insulated from cold weather.
The first phase of this study found at least three product lines in the Pacific Northwest that provide cost-effective domestic hot water for multifamily buildings. Electricity-related benefits were found to be significant, including energy use and peak power demand for large, multifamily buildings. Other benefits included freeing up useful space in the building and reduced cost of maintaining the water heating system.
 
Project Team
BPA: Kacie Bedney
Ecotope
 
Timeline
2009 – 2016
 
Reports
 
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