Industrial Grade Direct Fired Make Up Air Handlers

Welded Construction Make Up Air Units Ensure Indoor Air Quality (IAQ) in the Most Demanding Workplaces

The RAPID® 4000-Series is a customizable ultra-efficient direct-fired heating, cooling and pressurization system. Available from 5,000-150,000 CFM.

RAPID® 4000-Series are extremely durable and long-lasting, creating Rapid’s reputation for industrial-grade quality and long lifespan.  Constructed with an external skin welded to an internal welded structural steel framework, energy efficient airfoil fans and heavy-duty fan bearings with an ABMA L-10 rated life of 100,000 hours, energy efficient & low maintenance direct-fired burner and manifold.

Direct Fired Make Up Air Unit


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Model Configurations

 The units are available in four different air styles- MUA (100% outside air with a fixed discharge air volume), FR (fixed 80% return air / 20% outside air with a fixed discharge air volume), AM (modulating return air / outside air with a fixed discharge air volume) and VAV (100% outside air with a variable discharge air volume). These four different air styles, along with the availability of evaporative cooling, mechanical cooling, post-cooling reheat and a wide variety of accessories, make these units extremely flexible and able to meet a very diverse range of heating and cooling needs.

Typical Orientations

All models and air styles are available in upright and horizontal as well as indoor and outdoor configurations.

Upright Outdoor
Outdoor Make Up Air System
Indoor Make Up Air Unit
Horizontal on Legs (Indoor or Outdoor)
Direct Fired Make Up Air System
Suspended (Wall or Roof Inlet)
Upright Indoor
Roof Mounted
Commercial Rooftop Make Up Air


OA = Outside Air, DA = Discharge Air, RA = Return Air