Air Preheaters [APH] : Air Preheaters (APH) Air Preheaters (APH) is the Shell and tube type Heat Exchangers used for preheating the air which is fed to the boiler or furnaces/kilns for combustion of fuels. Its primary objective is to extract the waste heat from the flue gases leaving the boiler. Thermodyne Engineering Systems manufacture Air Preheaters and are Read more about Air Preheaters [APH]...