The most common types of these units are used for forced air heating and cooling systems, such as wood furnaces, boilers, stoves, and many others. ALFA water-to-air heat exchangers are also suitable for liquid cooling, as well as for a variety of liquid-to-air and liquid-to-liquid heat transfer applications. Aluminium is used as the fin material because of its high heat conductivity. The fin density is an impressive 12 fins per inch. It has a unique design that allows for heating loads of 50,000 to 60,000 Btu per square foot. Despite the high fin density, the flow resistance through the coils is surprisingly low.