Nu-Calgon - Evap Pow’r is a “no-rinse” product formulated for cleaning indoor evaporator coils. The green-colored, slightly alkaline liquid is metal-safe and therefore will not harm the coil’s metal surfaces when left in contact with them even in a no-rinse application. It cleans and emulsifies the most stubborn soils and deposits, and is biodegradable as well as USDA-Authorized.