Notes to Table C407.5.1(3) state that pump system power for each pumping system shall be the same as the proposed design. If the proposed design has no chilled water pumps, the standard reference design pump power shall be 22 W/gpm (equal to a pump operating against a 75-foot head, 65-percent combined impeller and motor efficiency). The chilled water system shall be modeled as primary-only variable flow with flow maintained at the design rate through each chiller using a bypass. Chilled water pumps shall be modeled as riding the pump curve or with variable-speed drives when required in Section C403.4.3.4.
Default chilled water loops for IECC Systems in ApacheHVAC are primary only configuration with constant flow on the primary loop. The primary loop has a specific pump power of 22 W/gpm with the pump riding the pump curve. When the requirement changes based on specifics in the code users will need to change the pump performance curve to variable speed using the pull-down menu in the chilled water loop dialog.
