Closed Loop Water Treatment

Treatment of closed hot and chilled water loops is essential for the proper maintenance of heating, cooling, and piping systems.

Closed system treatments aim to address the following:3

  • Corrosion control
  • Scale/deposit build up
  • Biological control
  • Freeze Protection
  • System Cleanings


GWT-Inc offers a variety of treatment solutions for these systems. Our treatments are formulated using industry standard chemical formulations and blends.

      Corrosion, scale, and deposit build up control:

  • Achieved through nitrite, molybdenum, or organo phosphonate based treatments. All of our formulations include adequate amounts of azole for soft metal control and have pH balancing properties.
  • We also have custom blended formulations for aluminum boilers.
  • We have custom formulations to fit almost any system requirement.

      Biological ControlLegionella Testing & Analysis

  • Achieved through addition of biocides such as glutaraldehyde, bellacide 355 or another proven bacteria killers.
  • In at high risk systems we recommend an annual system cleaning or dose of biocide.

      Freeze Protection

  • Achieved through ethylene or propylene glycol depending on system requirements and discharge regulations.
  • Our glycols come in any percent mixture with or without inhibitors.
  • We also offer greenER alternatives to the standard glycols on the market.

      System Cleanings

  • Achieved through mild cleaning compounds which penetrate deposit build up and scale on heat transfer surfaces.


General Comments:

  • Any water treatment plan for closed systems should be evaluated by corrosion coupon monitoring.
  • Periodic biological testing should be required for all closed systems.
  • Side stream filtration is essential to reduce erosion and increase system efficiency.