Is Your Closed Loop System Losing Water?

Locating Water Losses in Closed Loops

  • 12 December 2017
  • Author: Chem-Aqua, Inc
  • Number of views: 21427

Closed heating and cooling water systems typically require little makeup water and minimal chemical additions following the initial system charge. However, when leaks occur, it can be costly and difficult to maintain the treatment levels necessary for corrosion and deposit control. Routine testing of conductivity, pH or alkalinity, and inhibitor level is used to determine if there has been any water loss. If these parameters decrease simultaneously, water has been lost. If the water loss is significant (>1 gpm), a ¾” water meter installed on the makeup line (on a bypass) can help quantify the rate of water loss.


It is necessary to identify and eliminate the source(s) of significant water loss, as this will help improve treatment plan effectiveness, lowering operating costs and reducing the potential for unexpected system failure. The following checklist may help you identify why a closed system is losing water:


  • Check all circulating pumps for leaks around the packing seals
  • Check the expansion tank to ensure it is not full of water
  • Check all pressure relief valves
  • Check all automatic air vents to see if they are leaking water
  • Check the backflow preventer
  • Check to make sure you are NOT backwashing filters with system water
  • When fan coil units are used with a chilled water system, check the conductivity, pH, inhibitor level, hardness, or color (if a colored treatment product or a dye is used) of the water in the condensate drain pans
  • Where steam is used to heat a hot water system (via a heat exchanger), check for contamination in the various boiler system waters

You may think with a closed loop system you won’t have to worry too much about water loss. However, even the tiniest leaks can result in significant water loss if you let the system go long enough. This is why it’s important to monitor water levels and quality and, if you find any water loss at all, locate the source of the leak.


Since 1919, Chem-Aqua has provided custom-designed programs that solve water treatment problems and make boiler, cooling, and process water systems more efficient. Our success is built on our Total System Approach to water treatment. Long ago, we recognized that good results require a lot more than just adding chemicals and testing water. It requires a comprehensive program of products, equipment, and services that address the unique mechanical, operational, chemical, and people requirements of each system.


To learn more about Chem-Aqua’s services, including closed loop cleaning (cleaning, passivation, filtration, and corrosion inhibition), visit us at today for more information.


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