CALMAC® Ice Bank® Energy Storage Tank Model C

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CALMAC® Ice Bank® Energy Storage Tank Model C

  • Internal header with two, three, or four 4-inch flanged connections
  • Easily adaptable to reverse return configurations
  • Non-corroding materials of construction which is 99% reusable or recyclable
  • Indoor or outdoor locations, partial burial or total burial (link to spec)
  • Translucent heat exchanger tubes for easy visual inspections
  • Seamless one-piece tank provides structure and containment with no containment liners or moving parts to maintain
  • Factory assembled quality with cataloged charge and discharge performance curves
  • Modular design —so you can add more tanks over time and relocate them easily
  • Available in different sizes to accommodate differing space constraints
  • Counter-flow heat exchanger allows some of the warmest ice making temperatures in the industry for efficient charging and discharging
  • Can freeze solid without sustaining damage
  • Average lifetime —35+ years
  • Backed by a 10-year limited warranty

How Energy Storage Tanks Work

Thermal energy storage is like an "HVAC battery" for a building’s air-conditioning system. Trane Thermal Energy Storage systems use standard cooling equipment, plus an energy storage tank to shift all or a portion of a building’s cooling needs to off-peak, night time hours. Model C energy storage tanks store energy in the form of ice during off-peak periods when utilities generate electricity more efficiently with lower energy and demand charges. The stored ice is then used to cool the building occupants the next day, during the peak periods when utility rates are at their highest.

Built-in Convenience and Reliability

Developed in response to customer requests for more flexible siting and faster installation of storage tanks, the second-generation CALMAC  Model C tanks can be bolted to each other due to their internal headers and four inch flanges. Internalized headers eliminate most external piping (80 percent!) which results in a 20 percent smaller footprint requirement and more siting arrangement flexibility, cutting installation cost and time of installation.

High reliability – low maintenance

The second-generation Model C Thermal Energy Storage tank also features a 100 percent welded polyethylene heat exchanger and improved reliability, virtually eliminating maintenance. The tank is available with pressure ratings up to 125 psi.

Control strategies

There are any number of control strategies that can be utilized to take advantage of the benefits of thermal energy storage. However, there are two basic approaches that define the common limits of system design. Electric rates and building usage will determine which control strategies are best for the project.

  • Full Storage A chiller sized large enough to charge enough energy storage can shift the entire load to off-peak periods.
  • Partial Storage The chiller works in conjunction with the CALMAC energy storage tanks during on-peak periods to manage the building’s cooling load. During off-peak hours, the chiller charges the tanks for use during the next day’s on peak cooling period.

Glycol Recommendations

A secondary fluid is needed that can operate and flow at temperatures low enough to freeze water. An ethylene-based or propylene-based glycol solutions is recommended. A premixed solution of an industrial heat transfer solution that is specially formulated for low viscosity and superior heat-transfer properties should be used. Industrial based HTF’s contain a multi-component corrosion-inhibitor system that can be maintained and provide a long useful life.


You can maintain your CALMAC tanks and the energy storage system by using a maintenance process similar to that used for conventional cooling.

  • Perform chiller maintenance as required.
  • Ensure the controls are operating properly and in sync with the utility rates.
  • Check the health of the glycol fluid annually.
  • Check the water level in the tanks.
  • Add biocide as needed to eliminate algae growth.


Looking for BIM?

Select your Model C tank below and download CAD file for your project. 


Check out the links below to learn more about the benefits that thermal storage energy can provide for you.

Case Studies

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