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Measure: Replace Circulator Pumps with More Efficient, Variable-Speed Alternatives

Building Size: 5,000 gsf
Climate Zone: Hot - Humid

Measure: Replace Circulator Pumps with More Efficient, Variable-Speed Alternatives

Building Size: 5,000 gsf
Climate Zone: Hot - Humid
Replace Circulator Pumps with More Efficient, Variable-Speed Alternatives
Measure Simple Payback (years) Approximate Capital Cost ($) Annual Energy Savings (kBtu/sf) Annual Energy Savings (kBtu/yr) Annual Cost Savings ($/sf) Annual Cost Savings ($/yr)
Replace Circulator Pumps with More Efficient, Variable-Speed Alternatives 4 $575/pump -- 2,600/pump -- $114/pump

Description:

What Is This Measure?

Small circulator pumps (< 2.5 horsepower) propel fluid through closed-loop heating and cooling systems to regulate air or water temperature. Researchers evaluated new high-performance variable-speed circulator pumps with automated control that adjust pump speed to meet changing demand. They tested the technology in two common applications at the Denver Federal Center, a domestic hot water (DHW) recirculation system and an air handler unit (AHU). They found that the pumps reduced energy use 26% to 96%, with payback of less than 6 years. The new variable speed pumps should be considered as end-of-life replacements for all constant speed circulator pumps.

Special Considerations

Because differential pressure and accurate flow readings are not readily available for smaller constant-volume circulator pumps, use one of the following methods to right-size the pumps:

  • Determine pipe sizes and lengths and then calculate actual head loss from the pipes to estimate the flow (GPM) and head required for the pump.
  • Observe supply and return temperature differentials to make an educated guess about the existing pump’s suitability for that system. For example, if the Delta-T is extremely small (2°F to 5°F), the pump is most likely too big.

See GSA’s Proving Ground for more details on the field demonstration findings.