Measure Overview
This measure would prescriptively require circulator pumps serving central service hot water systems in nonresidential buildings to have advanced pump controls. Applicable controls would include controls that are internal or external to the pump that reduce energy use at the pump and/or water heater. The proposed control requirements would vary based on building size, application, water heating plant types, and distribution system designs. Proposed continuous pump control methods include but are not limited to pressure based variable speed control with thermal balancing valve(s), constat return temperature control, demand flow-based control, and digital timeclock. The proposed measure would be applicable to new construction, alterations, and additions.
This measure would include updates to Joint Appendix JA14 to add startup and field verification requirements for contractors based on the application and pump control strategy. Field verification would be via self-attestation on the design (NRCC, LMCC) and installation (NRCI, LMCI) forms.
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This measure page will be updated as the 2028 code cycle progresses. For questions or suggestions, email [email protected]. Please include the measure name in the subject line.
Scope of Proposed Code Change
| Building Type(s) | Construction Type(s) | Type of Change | Updates to Compliance Software | Third Party Verification |
| Nonresidential | New construction, additions, alterations | Prescriptive | Update existing feature, add new feature | No changes to third party verification |
Justification for Proposed Change
Currently, there is a mandatory requirement that circulating pumps are capable of automatically turning off. Projects typically meet this requirement via installation of a timeclock, however this method does not save energy while the building is occupied. Furthermore, the commonly used timeclocks are analog timeclocks that have limited configuration options. For example, they cannot be programmed with different schedules for the weekend versus weekday. These timeclocks also have persistence issues due to clock drift and daylight savings time changes. Some projects also include aquastat control of the pump, however there is no requirement for the aquastat set point and often the aquastat installation does not result in energy savings. There are no prescriptive requirements for advanced pump controls in Title 24, Part 6 for nonresidential buildings with central water heating systems.
The proposed code change would result in the reduction of energy from the water heater and the circulator pump. The water heater energy savings are due to the reduction in recirculation system pipe heat losses in pipes and reduced destratification. Reduced destratification also increases the viability and efficiency of heat pump water heaters. The pump savings is due to the pump operating at a reduced flow rate and reduced head loss in the recirculation system; this savings is partially offset by additional plant heating load since the portion of pump power delivered to the water ultimately ends up as heat, but all plant types will have at least a marginal net pump energy savings. The controls that the proposed code change would require are typically easier to set up and more persistent than analog controls.
Several studies have evaluated the benefits of electronically commutated motors (ECM) pumps and controls. Based on the Northwest Energy Efficiency Alliance (NEEA) study results, circulator pump controls reduced runtime between 55 – 85 percent, and increased water heater energy savings between 1 – 14 percent in nonresidential applications for varying controls (NEEA, 2019). The Statewide CASE Team was able to isolate the savings associated with the proposed controls from this study. The National Renewable Energy Laboratory (NREL) study suggests that ECM pumps with added controls can provide greater than 50 percent electricity savings at the circulator pump (Dean, Honnekeri and Barker 2018). However, this study does not separate out savings associated with controls and savings associated with the switch from an induction to ECM pump.
In addition to the above studies, TRC and 2050 Partners are working on a field demonstration study for circulator pump controls. The Statewide CASE Team will leverage data from this study to inform the energy savings for the proposed measure.
Relevant Documents
Round One Utility-Sponsored Stakeholder Meeting Materials
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The Statewide CASE Team values input from all stakeholders engaged in the Title 24, Part 6 code change process. We encourage the open exchange of code change comments and concerns.