HVAC-1 Heat Transfer Fluid Add Pak is a fully-formulated additive package developed for use with ethylene or propylene glycols, and may be used to make heat transfer fluids for HVAC systems, food processing heating and cooling units, process heat transfer systems, and more. HVAC-1 mixes readily with glycols at temperatures as low as 40ºF, and can be stored without crystallization above 50ºF. The ingredients in HVAC-1 inhibit corrosion of all metals commonly found in HVAC systems, and also are compatible with most plastic construction materials. Corrosion inhibition is provided in several ways: 1) metals are passivated, or protected, by thin, non-fouling molecular coatings ionically bonded to the surface; 2) pH of the glycol-water solution is buffered by an acid-neutralizing ingredient which acts to maintain the desired level of alkalinity; 3) dispersing-suspending agents help prevent scaling and fouling. Propylene or ethylene glycol containing HVAC-1 may be formulated to any concentration, with water containing up to 300 ppm (total) hardness (salts of magnesium, calcium, etc.). Higher hardness levels may cause excessive inhibitor consumption, scale deposits, and metal pitting.