Exploring Stelter & Brinck’s Duct Style, Gun Style, and Packaged Configurations
In a previous blog, we discussed the different types of indirect fired air heaters that Stelter & Brinck offers industry; this blog will discuss Stelter & Brinck’s direct fired air heaters.
At Stelter & Brinck, direct fired air heaters are a vital product of our array of process heating offerings. These systems deliver high-efficiency heat by mixing combustion gases directly with the process air stream—making them the ideal choice for applications where maximum thermal efficiency, lower operating costs, and high temperatures are priorities, and where combustion by-products are tolerable.
The images below provide a quick overview of S&B direct fired air heater types. In this post, we’ll break down the three primary configurations we offer: Duct Style, Gun Style, and Packaged. Each is custom engineered to match specific airflow, temperature rise, fuel type, emissions, and installation requirements while upholding the rugged durability for industrial processes.
Why Direct Fired Air Heaters?
Unlike indirect fired heaters, S&B direct fired air heaters apply heat directly to the process air stream via the burner. This design achieves the highest combustion efficiency with minimal heat loss, lower purchase and operating costs, and the ability to reach very high outlet temperatures (often 2000°F+).
They are widely used in heat treating, drying, curing, mining, printing, baking, composites, metals processing, and many other industries. Low-emission and ultra-low-NOx options are available across all models.
All S&B direct fired models are fully packaged or modular, tested in our facility before shipment, and supported by our expert field service and extensive parts inventory.
Duct Style Air Heaters (AHDX / AHDR)
Our duct style heaters are designed for direct insertion into existing process ductwork, offering a flexible, space-saving solution. Duct-style units heat fresh process air.
Key models and features include:
- Fresh Air Duct Section (AHDX): Uses oxygen from the process air stream (typically >18% O₂ by volume) for combustion—no separate combustion air blower needed. Ideal for clean or fresh air applications.
- Recirculating Duct Section (AHDR): Includes a dedicated combustion blower for dirty, hot, or low-oxygen recirculated air streams.
- Selective Catalytic Reduction (SCR) Heaters: Low-NOx systems for start-up or post-heating in utility boilers and similar applications.
Highlights:
- Horizontal or vertical orientations, indoor/outdoor trim
- High turndown, precise temperature control
- Easy integration with existing systems
- Robust, insulated construction with easy maintenance access
- Applications: baking, curing, heat treating, printing, drying, oilfields, and more
Duct style units excel when you need to add heat directly into ductwork without major system redesigns.
Gun Style Air Heaters
Gun style heaters are our solution for the most demanding conditions, including dirty or low-oxygen air streams. These units are capable of high mass flows and high temperatures.
Key features and benefits:
- Gas-only, oil-only (light, medium, or heavy), or combination gas/oil burners
- Single or multi-pass designs
- Ideal for high mass flows, recirculating streams, high temperatures, or fuel oil operation
- Stainless steel construction and low-emission options available
- High thermal turndown, PID control, flame observation ports, and easy access for maintenance
- Optional inlet filters, silencers, insulated shells, and remote interfaces
Common applications: Annealing, metal curing, glass curing, chemical drying, sludge and paint drying, and other rugged industrial processes.
Gun style heaters stand out for their versatility and ability to handle challenging process air conditions reliably.
Packaged Air Heaters
Our packaged air heaters are complete, skidded systems ready for fast installation—perfect for new installations or straightforward process heating needs.
Highlights include:
- Fully pre-piped, pre-wired, and test-fired with burner, process blower, controls, outlet transition, and motor starters/VFD
- Fired on natural gas, propane, butane (and other fuels)
- Flame safety and process temperature controls included
- Compact footprint with robust construction
- Low-emission options available
Applications: Dye and paint manufacturing, mold processing, drying, curing, printing, and general industrial airflow heating.
These units arrive on-site ready to connect and operate, minimizing field installation time and costs.
Choosing the Right S&B Direct Fired Air Heater for Your Process
All S&B direct fired heaters share core strengths: highest efficiency, custom engineering, low-emission capabilities, heavy-duty construction, and comprehensive support. The best choice depends on your needs:
- Heating fresh process air → Duct Style
- Dirty/low-oxygen air, high mass flows, or fuel oil → Gun Style
- Quick installation and complete system → Packaged
Our engineers evaluate your airflow, temperature rise, fuel type, emissions requirements, space constraints, and process details to recommend the optimal solution.
The Stelter & Brinck Advantage
With more than a century of process heat experience, we deliver proven engineered equipment. Every direct fired air heater is custom designed, thoroughly tested, and backed by responsive service and parts support.
Whether you need a duct-insert heater for curing, a gun-style unit for high-temperature drying, or a packaged system for manufacturing, the S&B direct fired family provides efficient, dependable performance.
Ready to discuss your application? Contact us today at (513) 367-9300 or visit stelterbrinck.com/contact-us. Our team will evaluate your requirements and provide a tailored recommendation.
Have questions about which direct fired type is right for your process? Drop a comment below or reach out directly—we answer every inquiry personally.
