This document summarizes the results of laboratory and field testing of variable capacity heat pump (VCHP) systems conducted by Bonneville Power Administration, EPRI, and Ecotope. Key findings include: - VCHPs can achieve 17-19% greater energy savings compared to minimum efficiency units according to lab testing in Seattle and Boise. - Field testing showed 25-30% improvement in performance for VCHPs compared to single-speed systems when modeled on an annual basis. - While duct losses were up to 5% greater for VCHPs due to lower operating airflows, lab and field data showed generally good agreement on system performance.

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Bonneville Power Administration
Variable Capacity Heat Pump Laboratory
& Field Test Results
26th Annual E Source Forum
September 17–20, 2013
Ryan Fedie
Engineering Manager, BPA Energy Efficiency
rtfedie@bpa.gov
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VCHP Indoor & Outdoor Unit
Credit: Walt Hunt, EPRI Labs
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VCHP Lab Testing
 Fan and compressor speeds generally track one another
through the operating modes
 Compressor speed increases as the outdoor
temperature decrease (reduces aux heat usage)
 Cyclic test: no affect on the performance of the system
 Frost Accumulation test: no degradation in capacity
output
 Savings over federal minimum efficiency unit: 17%
energy savings for Seattle, 19% for Boise
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VCHP Lab Testing
Capacity Curves of Energy Model Data
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Summary of Field Study
 Developed analytical tools to evaluate VCHP energy use
on an annual basis
 Good agreement between field data & lab data
 VCHPs perform at higher levels than single speed
systems
 Modeled performance with field data 25-30%
improvement
 Duct losses larger because operate at lower airflows –
however, only ~5% greater
 Equipment size, aux controls, setback behavior still
matter
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Summary of Field Study
 Developed analytical tools to evaluate VCHP energy use
on an annual basis
 Good agreement between field data & lab data
 VCHPs perform at higher levels than single speed
systems
 Modeled performance with field data 25-30%
improvement
 Duct losses larger because operate at lower airflows –
however, only ~5% greater
 Equipment size, aux controls, setback behavior still
matter
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Contact Information
BPA, Lab & Field Testing
Kacie Bedney, Research Engineer
Bonneville Power Administration
503.230.4631
kcbedney@bpa.gov
BPA Emerging Technology
Jack Callahan, Research Technical Lead
Bonneville Power Administration
503.230.4496
jmcallahan@bpa.gov
EPRI, Lab Testing
Walt Hunt. Project Engineer
Electric Power Research Institute
865.218.8184
whunt@epri.com
Ecotope, Field Testing
Ben Larson, Research Scientist
Ecotope, Inc.
206.322.3753, ext 207
ben@ecotope.com
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