Notes that glycols are used to prevent damage to HVAC equipment caused by freezing and corrosion. The two widely-used glycols ethylene glycol and propylene glycol have lower heat transfer characteristics and increased pumping requirements compared to water. The loss of heat transfer and the increase in pumping power are influenced by temperature and the concentration of the fluid. States that the physical effects of glycol are almost unnoticed in heating systems but in cooling applications the effect of glycol on system capacity must be carefully considered. Illustrates methods by which to reduce the impact of glycols when selecting cooling coils and chillers and reviews the benefits of these techniques.

Units: I-P 

KEYWORDS: year 1997, Heating, ventilation, air conditioning, antifreeze, inhibitors, corrosion, additives, cooling, heat flow