TES with Dow Fluids To prevent chiller freeze-ups and permit the manufacture of ice, fluid solutions used in TES systems must have a sufficiently low freezing point. To make ice, DOWTHERM ™ SR-1,  DOWFROST ™ HD, DOWTHERM ™ 10 and DOWFROST™ 20 Fluids are usually chilled to between -7°C and -3°C (20°F and 26°F). Specifying 25% solutions of these fluids yields freezing points below -10°C (14°F) for DOWTHERM ™ SR-1, and DOWTHERM ™ 10 Fluids and -9°C (16°F) for DOWFROST ™ HD and DOWFROST ™ 20.

Fluids, providing an adequate margin of safety below the system’s normal operating temperature to protect against chiller freeze-up. Since TES systems do not operate above 4°C (40°F), 25% solutions can typically be safely used without sacrificing corrosion protection. Note that use of good quality dilution water is especially critical at low fluid concentrations because impurities in the water can cause some inhibitor to precipitate out of solution. This precipitation reduces the level of corrosion protection, decreases heat transfer efficiency, and leaves piping and other components open to possible corrosion attack.

Ground Source Heat Pumps Ground source heat pump (GSHP) systems are a year-round, energy efficient heating and cooling solution for applications ranging from private residences to larger scale public and commercial buildings. GSHPs are water-based closed loops that transfer the heat of the earth to a building heat pump in the winter and transfer the heat of the building to the relative cool of the earth in summer months. Regardless of the size of the system, an efficient, high performance heat transfer fluid is an essential part of any GSHP system. In climates where temperatures drop below freezing, there is a need for freeze protection as well as efficient heat transfer. DOWFROST TM, DOWFROST TM HD,  and DOWFROST TM 20 Fluids are leading choices for GSHP service. Drawbacks of Methanol  Although methanol is sometimes specified for GSHP service, this fluid has some significant drawbacks. First, with a flash point of 12°C (54°F), methanol is highly flammable, posing a danger to installers and to building occupants should a leak occur.

Second, due to its flammability, methanol is classified as a hazardous waste upon disposal under the U.S. Resource Conservation Recovery Act (and is subject to similar regulations in other nations). Third, methanol is characterized as high in both acute oral and inhalation toxicity, which can pose additional health and safety risks for building occupants. Regulations in many areas actually prohibit the use of methanol in underground systems. Finally, because methanol is often sold as an industrial commodity it does not normally contain an industrial inhibitor package to prevent system corrosion. Advantages of Dow Fluids In contrast to methanol, DOWFROST ™, DOWFROST ™ HD, DOWCAL™ 20 and DOWFROST ™ 20 Fluids are propylene glycol formulations that are low in acute oral and inhalation toxicity and have no measurable flash points because they are mixed in solutions with water. Both Dow fluids feature industrial inhibitor packages designed to protect metals commonly used in HVAC systems. DOWFROST ™ HD and DOWFROST ™ 20 Fluids, in particular, are noted for the additional protection they provide for copper which is commonly used in GSHP system tubing and heat exchangers.

The handling, low toxicity, regulatory, and corrosion protection advantages of using DOWFROST ™ HD, or DOWFROST ™ 20 Inhibited Propylene Glycol-based Fluids will normally overcome the slight loss of heat transfer efficiency. In addition, at concentrations of 25% and under normal operating temperatures, the heat transfer
efficiency of DOWFROST ™ HD or DOWFROST ™ 20 Fluids compares very favorably to plain water or methanol. Pumping horsepower requirements of Dow inhibited glycol-based fluids are similar to, or only slightly higher than, those of methanol. DOWFROST™ HD and DOWFROST™ 20 Fluids provide the handling advantages of a propylene glycol fluid, excellent heat transfer efficiency, long-term system freeze and corrosion protection, low maintenance operation, lower long term fluid cost, and greater overall peace of mind at an initial fluid cost usually less than the overall installed system cost.

Hydronic/Radiant Floor Heating Systems
Long popular in Europe, hydronic (water) heating systems are becoming an increasingly attractive alternative to forced air systems for residential heating throughout North America. Hydronic heating systems consist of a boiler, a pump to circulate the heated water, a water distribution network, and a series of radiating surfaces located throughout the home
or embedded in the floor (radiant floor heating). Corrosion protection is a particularly important consideration when
selecting a heat transfer fluid for a hydronic heating system because the higher system temperatures can cause rapid degradation of some glycol fluids. DOWTHERM ™, DOWFROST ™ and DOWCAL ™ Inhibited Glycol-based Fluids offer industrial strength protection designed for higher temperature systems to help ensure long service life. In systems where contact with drinking water is possible, a fluid with low acute oral toxicity, such as DOWFROST ™ is recommended.
Secondary Grocery Store Refrigeration Loops
Secondary loop refrigeration systems replace the traditional single, high pressure direct expansion loop with an abbreviated expansion loop and a larger low-pressure, secondary loop filled with DOWFROST TM or DOWCAL ™ N Heat Transfer Fluid, providing even, constant, energy efficient refrigeration to frozen and chilled food display cases throughout the store.
Secondary loop refrigeration systems have been shown to reduce greenhouse gas emissions by reducing the total amount of refrigerant used. The systems also reduce overall energy consumption for supermarkets.
Solar Collection Systems
DOWTHERM ™, DOWFROST ™ and DOWCAL ™ Fluids are also used in solar collection heating systems to
extract solar heat and transfer it to heat buildings or water supplies. For domestic solar systems, DOWFROST ™ HD and DOWFROST ™ 20 Fluids are preferred due to the low acute oral toxicity of these propylene glycol based fluids.
Other Applications
Dow inhibited glycol-based heat transfer fluids are also widely used in a variety of other water-based systems, including ice skating refrigeration systems, fire hydrants, and fire sprinkler systems. In skating rink systems, for example, sub-freezing temperatures are maintained by circulating DOWTHERM ™ SR-1,
DOWFROST ™, or DOWTHERM ™ 10 Fluid throughout a network of pipes embedded in the concrete floor
beneath the ice. In contrast to calcium chloride solutions, which are often used in these installations, Dow inhibited fluids are inherently much less corrosive.