Video Overview


Freez-Therm is an inhibited ethylene glycol-based heat transfer fluid and antifreeze for chilled water, hydronic and other closed systems. It is formulated with a fluorescent green/yellow dye for leak detection and product identification and an industrial strength corrosion inhibitor designed specifically for HVACR systems. The corrosion inhibitor protects metals commonly found in both residential and commercial installations, including brass, copper, solder, steel and cast iron. Freez-Therm is a complete heat transfer fluid and freeze point suppressant.

Many commercial and industrial closed water systems are required to operate while being exposed to varying extremes in temperature. And, many times these extremes may approach the freezing point or the boiling point of the water. As a result, use of a heat transfer fluid in order to suppress the freezing point or raise the boiling point becomes a matter of system design.

In these applications, use of the heat transfer fluid will enable the system to operate at the desired operating temperature. In addition, the heat transfer fluid should contain a corrosion inhibitor to protect system metal as those types of systems are invariably troubled with corrosion. Inhibited glycols, ethylene or propylene, are typically the compounds used in these applications.

Click here to use our Glycol Addition Calculator.

Packaging Size Part Number
1 gallon bottle 4189-07
5 gallon pail 4189-05
55 gallon drum 4189-01
55 gallon drum (uninhibited) 4189-02


This product must be used in accordance to the following directions by HVACR professionals only.

  • Existing Systems: Entire system should be cleaned and flushed. Since Freez-Therm may or may not be compatible with other fluids in the system. We recommend flushing the system completely. It is also important to clean away rust, scale, sediment, etc. from fouled systems.
  • New Systems: These systems may be coated with cutting oils, grease, solder, flux, etc. Therefore, a thorough cleaning of the system is recommended; Use a 1% or 2% solution of trisodium phosphate (TSP), or other recognized low foaming, alkaline detergent cleaner.
  • Identify the level of freeze protection needed. Then, consult the table below to identify the percentage (of system volume) that Freez-Therm must comprise to achieve the desired protection. Always use a freeze protection level that is 5ºF below the lowest temperature the system will experience.
  • Identify the system’s liquid volume.
  • Multiply the listed percentage times the system volume to arrive at the required gallons of Freez-Therm.
  • Drain the system of sufficient water so that the needed Freez-Therm can be added.
  • Dilution with demineralized or deionized water is strongly recommended, particularly in areas with total hardness values greater than 100 ppm. 
  • Circulate for 24 hours and check with a glycol refractometer.
  • Burst protection, a level of protection that is sufficient where the system fluid doesn’t have to be pumped at the lowest anticipated temperature, can be achieved with 5-14% less Freez-Therm. Consult Nu-Calgon for details.
Freezing Point Temp ºF Freez-Therm % of System Volume Boiling Point Temp. ºF
32 0.0% 212
30 3.6% 213
20 16.7% 215
15 21.9% 217
10 26.3% 218
0 34.0% 221
-10 40.4% 222
-20 45.6% 224
-25 48.1% 224
-30 50.3% -225
-40 54.4% 226
-50 58.3% 228

Literature Downloads

Download the product bulletin and other relevant literature here.


Download a low resolution file of the product label here.

SDS Information

Read and understand the product’s Safety Data Sheet for precautionary and first aid information.


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