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Federal Register / Vol. 86, No. 87 / Friday, May 7, 2021 / Proposed Rules
rulemaking process. DOE uses qualitative and quantitative information to characterize the structure of the industry and market. DOE identifies manufacturers, estimates market shares and trends, addresses regulatory and non-regulatory initiatives intended to improve energy efficiency or reduce energy consumption, and explores the potential for efficiency improvements in the design and manufacturing of circulator pumps. DOE also reviews product literature, industry publications, and company websites.
Additionally, DOE considers conducting interviews with manufacturers to improve its assessment of the market and available technologies for circulator pumps.
1. Equipment Classes When evaluating and establishing energy conservation standards, DOE
may divide covered equipment into equipment classes by the type of energy used, or by capacity or other performance-related features that justify a different standard. 42 U.S.C. 6316a;
42 U.S.C. 6295q In making a determination whether capacity or another performance-related feature justifies a different standard, DOE must consider such factors as the utility of the feature to the consumer and other factors DOE deems appropriate. Id.
For circulator pumps, there are no current energy conservation standards and, thus, no equipment classes.
However, the 2016 Term Sheets contained a recommendation related to establishing equipment classes for circulator pumps. Specifically, Recommendation 1 of the December 2016 CPWG Recommendations suggests grouping all circulator pumps into a single equipment class, though with numerical energy conservation standard values that vary as a function of hydraulic output power. Docket No.
EERE2016BTSTD0004, No. 98
Recommendation at p.1
DOE requests comment regarding the CPWG recommendation to include all circulator pumps within a single equipment class, especially regarding interim market changes since the recommendation that may warrant changes to that recommendation. DOE
additionally seeks comment regarding whether the same recommendations should apply to SVIL pumps.
2. Technology Assessment In analyzing the feasibility of potential new energy conservation standards, DOE uses information about existing and past technology options and prototype designs to help identify technologies that manufacturers could
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use to meet and/or exceed a given set of energy conservation standards under consideration. In consultation with interested parties, DOE intends to develop a list of technologies to consider in its analysis. An initial list of those options appears in Table III.1 of this document. Each technology option is then described separately in the sections.

TABLE III.1POTENTIAL TECHNOLOGY
OPTIONS FOR CIRCULATOR PUMPS
Improved Hydraulic Design Improved Motor Efficiency Ability to Reduce Speed
a. Improved Hydraulic Design The performance characteristics of a pump, such as flow, head, and efficiency, are influenced by the pumps hydraulic design. For purposes of DOEs analysis, hydraulic design is a broad term used to describe the system design of the wetted components of a pump.
Although hydraulic design focuses on the specific hydraulic characteristics of the impeller and the volute/casing, it also includes design choices related to bearings, seals, and other ancillary components.
Impeller and volute/casing geometries, clearances, and associated components can be redesigned to a higher efficiency at the same flow and head using a combination of historical best practices and modern computeraided design CAD and analysis methods. The wide availability of modern CAD packages and techniques now enables pump designers to more quickly reach designs with improved vane shapes, flow paths, and cutwater designs, all of which work to improve the efficiency of the pump. In confidential interviews, manufacturers indicated that the potential for additional efficiency improvements from improved hydraulic design were fairly small.
b. Improved Motor Efficiency Different varieties or constructions of a motor have different achievable efficiencies. Two general motor constructions are present in the circulator pump market: Induction motors, and electronically commutated motors ECMs. Induction motors can have one of two configurations: Singlephase and three-phase. Single-phase induction motors may be further categorized to include split phase, capacitor-start induction-run CSIR, capacitor-start capacitor-run CSCR, and permanent split capacitor PSC
motors.

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The majority of circulator pumps currently available on the market use induction motors. The efficiency of an induction motor can be increased by redesigning the motor to reduce slip losses between the rotor and stator components, as well as reducing mechanical losses at seals and bearings.
ECMs are generally more efficient than induction motors because their construction minimizes slip losses between the rotor and stator components. Unlike induction motors, ECMs require an electronic drive to function. This electronic drive consumes electricity, and variations in drive losses and mechanical designs lead to a range of ECM efficiencies.
The performance standard for circulator pumps is based upon wire-towater efficiency, which is defined as the hydraulic output power of a circulator divided by its line input power. Wireto-water efficiency is commonly expressed as a percentage. The achievable wire-to-water efficiency of circulator pumps is influenced by both hydraulic efficiency and motor efficiency. DOE assessed the range of attainable wire-to-water efficiencies for circulator pumps with induction motors, and circulator pumps with ECMs, over a range of hydraulic power outputs. Because circulator pump efficiency is measured on a wire-towater basis, it is difficult to fully separate differences due to motor efficiency from those due to hydraulic efficiency. In redesigning a pump model to attain greater efficiency levels, manufacturers would likely consider both hydraulic efficiency and motor efficiency. However, manufacturers indicated in interviews that the energy savings potential of improving hydraulic efficiency is small compared to that of improving motor efficiency.
Higher motor capacities are generally required for higher hydraulic power outputs, and as motor capacity increases, the attainable efficiency of the motor at full load also increases. Higher horsepower motors also operate close to their peak efficiency for a wider range of loading conditions.10
Circulator pumps manufacturers manufacture motors in-house or purchase complete or partial motors from motor manufacturers and/or distributors. As a result, manufacturers may select an entirely different motor, 10 U.S. DOE Building Technologies Office. Energy Savings Potential and Opportunities for HighEfficiency Electric Motors in Residential and Commercial Equipment. December 2013. Prepared for the DOE by Navigant Consulting. p. 4. Available at http energy.gov/sites/prod/files/2014/02/f8/
Motor%20Energy%20Savings%20Potential %20Report%202013-12-4.pdf.

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