Make-Up Air Systems— Total SOLUTION™ Industrial Space Heaters (The Dragon™) Make-Up Air Heating & Air Conditioning (The Firefox™) 80/20 Pressurization & Recirculation (The 80/20 PR™) Indirect-Fired Make-Up Air (Pure Air™) Industry-Specific Applications Pure Air™—Indirect Fired Make-Up Air The "Pure Air" Solution provides clean, combustion-free make-up air with a high efficiency, stainless steel indirect-fired heat exchanger and modulating burner. Available in either a fixed 100% outside air design or 80/20 building pressurization design, the Pure Air model comes complete with controls, wiring and FM or IRI gas train. Unit capacity ranges from 3,000 CFM to 40,000 CFM and heat output from 150 MBH to 4,000 MBH. Units can be built for vertical or horizontal installation, indoors or outdoors. Optional features include: Double-Wall Construction Roof Curbs Discharge Diffusers with Adjustable Louvers Double-wall UL® listed flue Filters Cooling Coil section Evaporative Cooling Section