Fans for industrial boilers are used to introduce fresh air into the boiler in order to allow the proper maintenance of oxygen levels necessary for the gas combustion. Inlet guide vanes are used to regulate intensity and pressure, depending on the required temperature. Fan curves have to be of an anti-stall type. These industrial boilers are dedicated to oven applications, for glass or metal industries. Inside the oven, re-circulating fans are used to maintain uniform temperatures. Large centrifugal fans are also used for cooling oven wall cooling, allowing a longer lifetime.