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NC-v4 EAp2:Minimum energy performance

Regd. Primary Secondary Pump Arrangement in PRM Baseline System 8 Modelling

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Anurag Ghosh
Assistant Sustainability Manager
L&T Construction
LEEDuser Basic Member
2 thumbs up

Hello All,

Can someone clarify whether we need to have a primary secondary arrangement for pumps in chilled water as well as condenser water loops. I am not getting a clarity of this scenario in ASHRAE 90.1 2010 Appendix G.

Thanks in advance.

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Mon, 03/10/2025 - 12:06

Only the chilled water pumps are modeled as primary/secondary. The condenser water pumps are modeled as one per chiller. 
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Anurag Ghosh
Assistant Sustainability Manager
L&T Construction
LEEDuser Basic Member
2 thumbs up

Tue, 03/11/2025 - 11:39

Hi Tyler, thanks for the clarification. Can the condenser water pump be modelled in either side of the loop based on actual design? Our actual design incorporated a recirculating condenser water pump in the secondary condenser loop (i.e. from cooling tower to chiller ).

Tue, 03/11/2025 - 11:53

No, the Baseline is defined completely independently from the actual design. 
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Anurag Ghosh
Assistant Sustainability Manager
L&T Construction
LEEDuser Basic Member
2 thumbs up

Tue, 03/11/2025 - 12:21

Hi Tyler, so which loop will be the correct interpretation for placing the condenser water pump ? (one coming out from chiller condenser and getting connected to cooling tower or the one coming out from cooling tower and  connected to chiller condenser)

Thu, 03/13/2025 - 12:33

I don't think it makes a difference because the condenser water flow rate would be the same on either side of the cooling tower. 
Profile picture for user anuragg
Anurag Ghosh
Assistant Sustainability Manager
L&T Construction
LEEDuser Basic Member
2 thumbs up

Fri, 11/14/2025 - 09:34

Hi, I am sorry to open this old thread. I understand we keep primary secondary arrangement in CHW loop. Also, we model the secondary pump with VFD. Hope the primary pumps are to be kept as constant flow types?

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