Variable chilled water flow saves money! Most people I know today like that idea. To understand this take a look at the following diagrams of a chilled water coil.
Chilled water coils are one of the principle components of an air conditioning system. They are used to cool air that is delivered to the office, the conference room, the cubicle – all those places we occupy during those hot summer days we love so much.
Three-way valves….Bad!
The amount of cooling that a coil can deliver to that hot office of ours is proportional to the amount of chilled water we can push through it. When it’s hot outside, we push a lot of chilled water through the coil. When it’s nicer outside, we can push less chilled water through the coil.
Take a look at the three-way control valve set up. This configuration represents the way we, as engineers, used to do it. Using that three way control valve, we could reduce the cooling delivered by simply bypassing flow around the chilled water coil. Using this method, while varying the cooling delivered, the system chilled water flow remains constant. Consequently, the pumps moving that water operate at a constant speed. The system pumps and system chiller liked that. It was simple, but it really wasn’t the most efficient way to deliver cooling to our working/living environments.
Two-way valves….Good!
Now look at the two-way control valve set-up. In this configuration, when we reduce the amount of chilled water flowing through the coil, we’re reducing the amount of water our system pumps have to deliver. We are now using VARIABLE CHILLED WATER FLOW!
With the newer technologies available to us today, like variable speed drives for our pumps and more sophisticated controllers on our chillers, we can save a lot of energy. SAVES MONEY TOO!
