Primary-Secondary Loop vs. Primary only Loop (with VFD)
Primary-Secondary Loop vs. Primary only Loop (with VFD)
(OP)
All:
First let me apologize if this has been addressed. I tried the search feature and didn't come up with anything so I figured I would just ask.
I am working with an energy consultant to try to optimize the chiller plant at my facility which consists of 3 Trane 1500 ton chillers feeding a primary-secondary chilled water loop. The chillers are variable, the primary pumps are constant speed, and the secondary pumps are VFD. Chillers are staged to meet demand based on flow and the unfortunate conseqence is that our chillers spend most of the summer running at 50-60% which is the worst place on their efficiency curves.
I was wondering if someone which chiller experience could explain some of the pros and cons of the primary-secondary vs. primary only chilled water loop arrangement.
Thanks.
First let me apologize if this has been addressed. I tried the search feature and didn't come up with anything so I figured I would just ask.
I am working with an energy consultant to try to optimize the chiller plant at my facility which consists of 3 Trane 1500 ton chillers feeding a primary-secondary chilled water loop. The chillers are variable, the primary pumps are constant speed, and the secondary pumps are VFD. Chillers are staged to meet demand based on flow and the unfortunate conseqence is that our chillers spend most of the summer running at 50-60% which is the worst place on their efficiency curves.
I was wondering if someone which chiller experience could explain some of the pros and cons of the primary-secondary vs. primary only chilled water loop arrangement.
Thanks.





RE: Primary-Secondary Loop vs. Primary only Loop (with VFD)
Good on ya,
Goober Dave
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RE: Primary-Secondary Loop vs. Primary only Loop (with VFD)
RE: Primary-Secondary Loop vs. Primary only Loop (with VFD)
RE: Primary-Secondary Loop vs. Primary only Loop (with VFD)
RE: Primary-Secondary Loop vs. Primary only Loop (with VFD)
If you are running variable speed compressors on your chillers and staging them correctly, I highly doubt that your 50-60% load is an inefficient operating point and I even more doubt that converting to primary-only will provide payback in any realistic time frame or building engineer's lifetime. Tell your energy consultant to hire a payback consultant and focus on optimizing the existing plant.
RE: Primary-Secondary Loop vs. Primary only Loop (with VFD)