The small door located at the bottom of the Corsair Arch front, is actually a “Draft Door” but it is quite often mistaken for an Ash Door. This door’s purpose is to allow oxygen into the firebox. It needs to be opened in a natural draft evaporator to allow air to feed the fire. In contrast, if the evaporator is employing a Forced Draft System, the Draft Door should remain closed to help guide the air from the blower upward into the firebox.
Fellow sugar maker, Mark Kellner of St Germain, Wisconsin, shared a tip showing how he uses the Draft Door on his Corsair Evaporator with Forced Draft System. (Just note, this is a “Draft Door”.)