Direct Fired IndustrialThe Rapid 4000 Series is a semi-customizable direct-fired heating, cooling and pressurization air handling or make-up air system. Rapid 4000 Series air handler's differentiating features include a wide airflow capacity range (up to 150,000 CFM); energy efficient direct-fired burner technology; energy efficient backward incline fans as standard; a long list of standard and semi-custom options; DDC controls options; and robust cabinet construction using structural steel with welded panels making them suitable for heavy-duty industrial applications.

 The FOur OptiOns

The Make-Up Air (MUA) unit is the simplest operation option. MUA units bring in 100% outside air, heat it to the desired setpoint and deliver it to the condition space. It supplies direct heated replacement air to make-up for building mechanical exhaust.  This option is ideal for any building with exhaust fans, units can interlock with fans to only operate when exhaust fans are operating.  Ideal for buildings with processes that require exhaust fans, vehicle maintenance/automotive repair, welding shops, commercial kitchens and restaurants.


The Fixed Recirculation (FR) systems always uses 20% outside air and 80% return air. This air handler operation is ideal for buildings that require a lower fixed volume of outdoor air for code compliance or other reasons.  Since all direct-fired heaters require a minimum of 20% outside air while in operation, this is the most energy efficient operation with the least allowable amount of outside air and the most recirculation.


Lastly, Variable Air Volume (VAV) units are perfect for buildings that require a varying outdoor air ventilation load but don't want to recirculate air from within the space.  VAV is similar to MUA since the unit is always providing 100% outdoor air, however VAV units are equipped with a variable frequency drive to provide for an air volume reduction of up to 50% for energy savings when less make-up air is required in the space.


The Air Management (AM) unit controls the outdoor air / return air ratio to adjust to variations in indoor air temperature and indoor building pressure conditions.   The system can continuously vary from 20% outside air with 80% recirculation for maximum fuel efficiency to 100% outdoor air with no recirculation for maximum make-up air and pressure recovery.   Air Management (AM) option can automatically adjust (no need for interlocks) to intermittent and unplanned building pressure or IAQ changes from intermittent building processes, exhaust operations and opening/closing doors.  Ideal for buildings with multi-functional spaces with varying conditions or varying occupancy periods throughout the day.   Ideal for manufacturing, transportation and logistics hubs, distribution centers and more.

 Benefits and Features

The 4000 Series units are perfect for industrial applications. They are constructed with an external skin and welded to an internal structural steel framework. This rugged industrial-grade construction provides decades of durability allowing for usable life years beyond the typical lifespan of commercial-grade air handlers. We utilize energy efficient backward incline fans that provide quiet operation and high static pressure capability. As a bonus, these fans do not collect dirt, buildup or debris, ensuring reduced vibration for the life of the air handler.

 All our units are designed to provide:

  • Improved Indoor Air Quality
  • High Efficiency Burner and Fan Designs
  • Automated Operation
  • Longer Service Life, Highest overall purchase value

Additionally, one of the biggest advantages of these air handlers is how customizable they are. Mix and match various combinations of optional sections and choose from a broad range of sizes and options to meet your design requirements. We offer a variety of configurations. Choose from several alternative heat sources, like electric, hot water or steam. Rapid Engineering also offers optional cooling packages to be paired with your air handler. Pick between evaporative cooling or mechanical cooling (reheating after cooling is also available for dehumidification).

Not only are Rapid 4000 Series air handlers extremely efficient, they are also offered with intelligent control features. These controls can module can monitor, diagnose, log and report more than 30 functions, including temperature, humidity and building pressure. Experience the Windows™ interface, which simplifies control and setup changes. Hourly collection of data allows trending and in-depth analysis at any time of the day. Units are also completely compatible with modern communication protocols, like Lonworks®, Bacnet®, ModBus® and more.


 pair it with cooling:

During the warm weather, the fan can operate as ventilation for cooling, or the air handler can be equipped with mechanical cooling.

Cooling options can be added by simply installing coil sections equipped with the appropriate cooling coils and a condensing unit or chiller.

 The Rapid Engineering EXPERIENCE 

We've been helping customers purchase and design their perfect air handler for over 50 years. With heavy-duty construction, high efficiency standard components, a long list of options, the ability to customize, the availability of evaporative cooling, mechanical cooling and post-cooling reheat, our units are extremely flexible and able to meet a variety of heating and cooling needs.

For more information on our 4000 Series of industrial air handlers or to speak with a Rapid Engineering expert, please contact us.