is air preheater a type of heat exchanger?
Yes, air pre heater is a type of heat exchanger which may be direct contact or in-direct contact [there is a separating medium between heating media and air.] Read below: An air preheater (APH) is a general term to describe any device designed to heat air before another process (for example, combustion in a boiler) with the primary objective of increasing the thermal efficiency of the process. They may be used alone or to replace a recuperative heat system or to replace a steam coil.
air preheater can mean a lot of different things. If it's the one used in a home heating system with a heat exchanger where heat is taken from the exhaust air and used to heat the incoming air, yes. .
