This topic has come up a few times but I am still somewhat confused as to how to determine the overall baseline building pumping power for a primary/secondary chilled water system.

Each chiller on the primary loop is to have its own chilled water and condenser water pump. The chilled water and condenser water loops have a pump each.

My question is ? what flow rate do you use when setting the W/gpm? Previously, I have been using the secondary chilled water loop flow for determining the 22 W/gpm ? split over the primary and secondary loops. Similarly, I had been using the cooling tower loop flow for setting the overall 19 W/gpm for the condenser water system.

Today I am reading the PNNL 25130.pdf manual. In 3.7.5, it states, ?Each chiller has its own primary and condenser water pumps that operate when the chiller is active?. Then it states, ?All primary pumps shall be 9 W/gpm and the secondary pump shall be 13 W/gpm, and the condenser water pump is assumed to be 19 W/gpm.?

Where it states, ?All primary pumps shall be 9 W/gpm?, does this mean all the pumps associated with the chillers ? chilled and condenser water? Or just the primary chilled water pumps? If just the primary chilled water pumps and not the chiller condenser water pumps, then what pumping power should the chiller condenser water pump have?

Christopher Jones, P. Eng.
Rowan Williams Davies & Irwin Inc.
Consulting Engineers & Scientists
901 King Street West, Suite 400, Toronto, Ontario, M5V 3H5
T: (519) 823-1311 ext 2052
M: (416) 697-0056

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