Economizer coils are used in downstream of Boiler bank to preheat the feed water absorbing heat from hot exhaust gases.Economizers are always water tube type. Economizers have different types of Tubes depending upon the application. Bare tubes in Economizers are widely used in Industrial boilers and for applications like Heat recovery boilers. Finned tubes are popular in HRSG applications. Feed water can be heated up to a level about 20 – 30O C below saturation temperature of the boiler.