Now that temperatures are falling and central chilled water plants are going offline, it may be time to measure how your plant performed this past summer. Were you able to distribute chilled water at design temperatures throughout your building or campus? Were you able to maintain designed temperature splits? Were the spaces served by your central plant comfortable?
How you maintain and operate your central chilled water system will impact the comfort level you are able to maintain within your building(s) as well as the energy cost you will incur. If your chilled water temperature splits are not what they should be, or if your chilled water supply temperatures creep above design conditions, this may be indicative of a larger problem.
Many systems, especially larger campus primary-secondary systems, experience problems distributing cooling capacity from the central equipment to the end user. The root cause of many of these problems is related to the flow rates associated with the primary and secondary loops. When the secondary loop flow rate exceeds the primary loop flow rate, the system becomes “waterlogged.” This results in the secondary loop becoming “starved” for chilled water and consequently relies on mixing the secondary loop chilled water return flow with the primary chilled water supply to meet the flow demands of the secondary loop. This type of operation will result in elevated chilled water supply temperatures and will impact the performance of the connected terminal equipment/buildings causing more energy to be expended both in pumping and fan horsepower.
This is just one of several reoccurring problems that we have found while investigating the operation of central chilled water plants. Now is the time to evaluate, diagnose and fix potential operational problems with your plant, before you need chilled water and before the impact of inefficient operation is magnified by the projected utility rate increases.