High Static Fresh Air Supply


The High Static Fresh Air Supply (HS FAS) provides a versatile heating system for applications requiring the ducting or filtering of make-up air. Supporting up to MERV 10 filters or 2.5 inches of ducted static pressure, the HS FAS is the perfect make-up air heater for interior rooms such as kitchens, painting, plating, welding, etching, and other food or chemical processing facilities.


  • Delivering 2.0" to 2.5" of static, allowing the unit to be located in the middle of a large space or ducted to a location inside the space.
  • Unique integral face and bypass damper-modulated air flow system, and hot water or steam source heat with 3/8" fin tubes the IFB coil regulates the outlet temperature.
  • High efficiency EC plenum fan.
  • Horizontal package comes with a 45 degree inlet hood, space for a mixing box, and filters.
  • Two versions of controls are available: Constant volume Airflow, delivering the catalog CFM regardless of static pressure. True DDC operation allowing the unit to integrate with an existing building management system or act as a standalone control.
  • Ranges from 855 CFM to 10,000 CFM.
How It Works

The LJ Wing high static fresh air supply unit fills a special combustion air need.

In many cases providing preheated combustion air to a boiler room requires higher static pressure than a standard fresh air supply unit can provide. In those applications LJ Wing turns to their unique High Static FAS unit. This unit is typically mounted in an outside wall and uses a direct drive motor to spin a blower capable of up to 2.5" of static pressure. Colder outside air is drawn into the unit and passes over an LJ Wing steam or hot water coil before discharging the air into the boiler room. The higher static capability allows you to specify a filter section with up to MERV 10 filters and/or a mixing box.

Optional motor configurations

LJ Wing combustion air systems offer variable capacity control

Modern boiler rooms contain multiple boilers or boilers with variable capacity as a means to reduce energy use. This type of configuration requires a combustion air preheating system that can match the load as it varies. LJ Wing high static FAS units are available with either VFD drives for AC motors or with electronically controlled ("ECM") motors to vary the air intake as needed in response to the overall boiler room controls.

Typical wall mount application

High Static FAS units are designed for wall mounting.

The most typical mounting arrangement for the high static FAS is a wall-mounted configuration. In those cases most of the unit is indoors and supported by braces attached to the wall. When ordered with the wall mounting kit a 45 degree intake hood is included to minimize entrainment of water.

Two types of controls available

Control options include DDC or electromechanical...

With 2 types of controls available, the LJ Wing combustion air preheater provides flexibility in application. The optional DDC controls can also be integrated with the Mestek "HeatNet" system that controls multiple boilers and provides real time monitoring.