Run Around Coils

A Run-around coil is a type of energy recovery heat exchanger that is often found installed within the supply and exhaust air streams of an air handling system to recover the heat energy. Normally it refers to any intermediate stream used to transfer heat between two streams that are not directly connected for reasons such as safety and practicality. Typically a runaround coil system consists of two or more multi row finned tube coils that are connected to each other by a pumped pipework circuit. The pipework is charged with a heat exchange liquid, usually water which absorbs the heat from the exhaust air coil and gives out heat to the supply air coil before returning again. In this way heat from the exhaust air stream is transferred through the pipework coil to the circulating liquid and then from the liquid through the pipework coil to the supply air stream.