L. J. Wing VIFB vertical tube integral face and bypass coils preheat outside air for air make-up systems. Because the VIFB coil operates with full steam pressure or constant water flow at all times, it prevents breakdowns in the central system caused by freezeup. The temperature of the discharge air is controlled by proportioning the entering air through the multiple heating and by-pass channels. The air is proportioned by the unique clamshell-shaped dampers which maintain a constant pressure drop, thus allowing a constant volume of air to pass through the unit. Performance can be calculated by using the L.J. Wing specifier program.

For more information, request bulletin VIFB.


  • Air make-up heating with steam or hot water
  • Maximum freeze protection
  • Constant volume
  • Minimum temperature override
  • Minimum stratification
  • Accurate temperature control
  • Sizes from 600 to 77,220 CFM
  • Performance certified to ARI standard 410
  • ETL listed to UL standard 1995
  • Hydrostatically tested to 500 psig.
How It Works

When the outside air is too cold to enter the air handler without freezing the coil or damaging other components...

When the outside air is very cold and full heat is needed from the coil, the bypass dampers will close completely. This will expose the air to the full face area of the coil. Since the LJ Wing integral face and bypass coil is designed to operate at full steam pressure all the time the coil tubes are protected from damage caused by very low entering air temperatures.

How It Works

When the outside air is not quite warm enough to enter the air handler without partially raising the temperature...

As the outside air warms up the bypass dampers will begin to close and regulate the coil leaving air temperature according to a downstream thermostat setting. The bypass dampers will both block a portion of the steam or hot water coil face and open a path for the outside air to pass through without being heated. The "blended" hot and cold air will mix to maintain the target supply air temperature.

How It Works

When the outside air is finally warm enough to enter the coil and the unit without risk of damage....

When the outside air temperature is sufficiently warm enough to be introduced into the unit without risk of damage, the bypass dampers will open completely and allow all of the air to pass through without being exposed to the coil surface. The coil is still at full steam pressure but now will only provide a slight temperature rise. The dampers will continue to modulate as needed to maintain the target supply air temperature without the risk of freezing as the outside air temperature varies throughout the day and night.

How it's Made

Formed steel damper blades are opened and closed by the face mounted actuator.

LJ Wing coils are constructed with heavy duty steel damper blades that are opened and closed by the available face mounted actuator. Actuators can be pneumatic, electric, or digital as required by the master control system. By mounting the actuator on the face of the coil the air handler manufacturer has room for installing the Wing coil in more narrow air handlers.

How it's Made

High pressure rated welded steel headers evenly distribute steam or hot water to the coil tubes.

Although most coils are operated at less than 20 psi pressure, LJ Wing coil headers are tested to pressures as high as 500 psi in order to assure safe operation in compliance with UL standard 1995. The heavy gauge headers incorporate a centrally located inlet pipe. CFD modeling of steam distribution, as well as 50 years of experience, have shown this location to provide the most even steam distribution in these vertical tube coil configurations.

How it's Made

LJ Wing copper tube and aluminum fin coils are factory assembled in Dallas

LJ Wing coils are standard with copper tubes and aluminum fins that are pressed onto the tubes. Fins for LJ Wing coils are flat, with no corrugations or lances. Since the coils are designed to handle outside air the possibility of dirt or debris collecting on the coils is real and the flat fin design makes it much easier to clean the coils and maintain optimum performance for many years. Coil tubes are soldered to the steel supply and return headers and pressure tested against leaks.