ASHRAE 90.1 primary secondary loop pump power

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Hi all,

First of all I would like to thank everyone in this forum for providing
very valuable information to less experienced LEED modelers energy like
myself.

I have a short question regarding the ASHRAE 90.1 Baseline pump power.
Currently, I am modeling a VAV system with two central plant chillers.
The cooling load is more than 300 tons therefore Appendix G says model
the baseline chilled water loop as primary - secondary with a variable
speed secondary pump. Also the pump power should be 22 W/gpm.

Now, I have 3 pumps in my chilled water loop (2 primary pumps and a
secondary pump). So should I set all of these pumps to have a pump power
of 22 W/gpm? It feels like cheating if I assign 22 W/gpm pump power to
the primary pumps as the head loss in primary loop would be much less
than the secondary loop in general. What do you think?

I really appreciate any inputs in this matter.

Thanks in advance for all the responses.

Alper Erten

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