Learn more about ethylene and propylene glycol.

Process Fluid Recommendations

For recommendations on the correct process fluid to use in your chilling system, refer to the manufacturer of the equipment served by the chiller. Most manufacturers have a specified type of fluid for correct system operation. Use this document as a guide if the heat-transfer fluid is specified as water.

Using Water for the Chiller Process

Dimplex Thermal Solutions recommends the use of an industrial inhibited glycol and water mixture in its water chiller systems. Ethylene and Propylene are the two standard types of inhibited glycols that can be used in Koolant Koolers chillers.

Purposes of glycol in Koolant Koolers chillers:

  •  The main job of glycol is to prevent freezing of the process fluid and ensure consistent flow at the operating temperature.
  •  Inhibited glycols will also prevent formation of scale and corrosion while protecting metals such as brass, copper, steel, cast iron, and aluminum.
  •  Water systems treated with inhibited glycol will also be protected from algae and bacteria that can grow and degrade the fluid system performance.

Important glycol facts for use in Koolant Koolers chillers:

  •  Do NOT mix different types or brand names of glycol. This can result in some inhibitors precipitating out of the solution, it will also gel and clog filters and prevent proper flow rates. If switching types, will need to run a thorough flush and clean of the fluid system. Once that’s done, it’s okay to change over.
  •  Do not use automotive grade anti-freeze in the chiller process. These types of glycols are not designed for industrial applications and may cause problems with heat transfer or fluid flow. Many automotive glycols contain silicate-based inhibitors that can coat heat-exchangers, attack pump seals, or form a flow restricting gel.
  •  Check state and local codes when selecting the process fluid. Certain areas may have environmental regulations concerning the use and disposal of glycol or other additives.

Ethylene Glycol (K-Kool-E)

Ethylene glycol is the standard heat-transfer fluid for most industrial applications. This type of glycol can be used in any application where a low-toxicity content is not required. Ethylene glycol has moderately acute oral toxicity and should not be used in processes where the fluid could come in contact with potable water, food, or beverage products.

Propylene Glycol (K-Kool-P)

Propylene glycol maintains generally the same freeze protection and corrosion and algae prevention as ethylene glycol, but has a lower level of toxicity. This type of glycol is more readily disposable than ethylene and safer to handle. Propylene glycol is commonly used in the food industry and applications when the user may come in frequent contact with the fluid.

Differences between Ethylene and Propylene Glycol

  •  At very cold temperatures Propylene becomes more viscous, which changes the heat exchange rate slightly. Koolant Koolers chillers are designed for that compensation, so that you can use either type.
  •  Ethylene is more widely known because large factories where there could be thousands of gallons in use generally purchase as it’s slightly less expensive.
  •  Koolant Koolers reason for recommending Propylene is because it’s MSDS handling is less rigorous which makes it easier for the facility maintenance staff if they need to ever fill or clean up a spill, etc. Also, some states and municipalities prohibit the use of Ethylene for environmental reasons.


When selecting the water to mix with the glycol, use a good quality, filtered source that meets the requirements of the process machine manufacturer.

  •  Dimplex Thermal Solutions recommends the use of distilled or reverse-osmosis water for the glycol / water mixture.
  •  De-ionized water can be used to fill the chiller process initially, but should not be maintained to a de-ionized state thereafter. Unless the chiller has been ordered and designed for the use of water that is continually de-ionized, the fluid will actually attack certain metals within the chiller and cause damage to some components. Damage caused by the use of maintained de-ionized water in a chiller not designed for it will not be covered under warranty. Consult Dimplex Thermal Solutions before using de-ionized water to check for compatibility.
  •  The use of regular tap water is NOT recommended. Water from the “city” or “ground” contains deposits and additives which can decrease component life and increase maintenance time.

Water/Glycol Mixtures : What ratio of Water to Glycol should I use?

The location of the chiller and environmental concerns must be taken into account when selecting the proper mixture of glycol and water for the chiller process. A process which is located completely indoors and has no chance of freezing will require less glycol than a system located outdoors where low temperatures can cause the fluid to freeze and piping to burst. Applications that have a very low operating temperature (below 20°F) should use a glycol mixture equivalent to an outdoor system. After selecting the proper glycol and water types, use the following chart to determine the recommended mixture depending on application and location of the process. The glycol percentage figures in the chart below will apply to any brand of ethylene or propylene glycol.

ApplicationGlycol %Water %Freeze Protection**Burst Protection
Indoor Chiller and Process 30 70 5°F / -15°C -20°F / -29°C
Outdoor Chiller / Low Temp. System 50 50 -35°F / -37°C -60°F / -60°C

Fluid Maintenance / Filtration

Maintaining clean process water and the proper glycol content will extend the life of the system and reduce costly down-time. If the chiller was not equipped with a fluid filter from the factory, it is highly recommended to install some sort of filtering system to remove unwanted dirt and debris. Refer to the “Chiller Maintenance” section of the manual for water and filter maintenance information.

Advantages of Purchasing Glycol from Dimplex Thermal Solutions

  •  If the glycol is purchased with the chiller, it eliminates unknowns and variables in the installation process.
  •  There is consistency with the installation and the knowledge that the right fluid, purity, and dilution ratio are in place at the facility, which assists in equipment reliability rates.
  •  For replacement fluid filters, spare parts, and glycol, contact our sales desk by email.
  •  For questions regarding process fluids, contact one of our sales engineers by email.

Recommended Glycol Concentrations:

  • Indoor Chiller and Process:
    30% Glycol
    70% Water
    -15°C / 5°F Freeze Protection **
    -29°C / -20°F Burst Protection
  • Outdoor Chiller / Low Temperature System:
    50% Glycol
    50% Water
    -37°C / -35°F Freeze Protection **
    -51°C / -60°F Burst Protection

Contact us to purchase 55 gallon drums, or 5 gallon buckets of Ethylene Glycol.
** Figures based on performance of DTS “K-Kool-E” brand of Ethylene Glycol, with an operating set point above 40°F.

Warning: Do NOT use automotive anti-freeze in your chiller application. This will void the warranty and can cause severe damage to chiller components.