Heat Transfer Fluid (Glycol)

The three main types of solar thermal systems are open direct, drainback and glycol. Open direct systems are appropriate only where there is little to no chance for freeze damage, such as Hawaii, Costa Rica. For freeze protection, either glycol or drainback systems must be employed.

Generally, when comparing glycol and drainback systems, drainback systems are lower in cost, easier to install, and less subject to maintenance requirements. Where a drainback system isn’t feasible or desired, glycol systems are the next best choice for freeze protected solar hot water.

SHEM recommends and supplies DOWFROST glycol. DOWFROST™ heat transfer fluid contains specially formulated packages of food grade industrial inhibitors that help prevent corrosion, operate effectively within wide temperature ranges, and importantly meet the requirements of the Uniform Solar Energy Code.

The Uniform Solar Energy Code, Section 405.1.1, Single-Wall Heat Exchangers, requires that heat transfer medium shall be water or other nontoxic fluid having a toxic rating or Class of 1 as listed in Clinical Toxicology of Commercial Products, 5th edition.

DOWFROST complies with this, as well as United States Department of Agriculture (USDA) and Food and Drug Administration (FDA) regulations for food safe additives.

For more information, please see www.dowfrost.com.