It is designed so that the frame dimensions are slightly smaller than duct dimensions. The entire heater except the terminal box slides through a rectangular opening in the side of the duct with ΒΌ clearance all around. When installed, the face area of the heater is at right angle to the air stream. Slip in heater is widely used because it allows duct work to be installed before the heaters are available, simplifies on changes in heater location and it is easily installed into existing duct systems. Furthermore small slip-in heaters may be installed without any special arrangements for their support.
slip-in heater mounted in a flanged duct section. Frame dimensions are made to match exactly duct dimensions. The frame is then attached directly to external flanges of the duct where the slip-in portion could be pulled out without removing flanges from duct. All controls are mounted in the terminal box of the slip in portion.