Boilers are used in thermal power plants to help facilitate the removal or dispursion of fumes resulting from combustion. Forced draft (FD) fans help to move outside air into the system, whereas induced draft (ID) fans remove air within the system to the outside atmosphere. Both FD and ID fans are used to help the flow of air and gases through the furnce of a boiler system. The biggest advantage using FD fans comes from them supplying more air to the boilers, which increases the heat transfer rate, thereby reducing the size of the boiler resulting in space and energy savings. Due to the corrosive environment, ID fans typically will need to be built to withstand the corrosive and erosive enivronments.