At Stelter & Brinck, one of our core product lines is our family of indirect fired air heaters (IAH). These systems deliver clean, contaminant-free hot air by separating combustion gases from the process air stream—making them ideal for sensitive applications where product purity is critical.
The image above provides a quick overview of S&B IAH Types. In this post, we’ll break down the three primary configurations we offer: Recirculating (IAH-R), Non-Recirculating (IAH-NR), and Straight-Through (IAH-ST). Each is custom-engineered to match specific airflow, temperature, efficiency, and space requirements while maintaining the rugged durability our customers expect.
Why Indirect Fired Air Heaters?
Unlike direct-fired heaters, S&B indirect air heaters use a heat exchanger to transfer energy from the combustion side to the process side without mixing the two streams. This design ensures the heated process air remains free of combustion by-products such as NOx, CO, or excess moisture. Applications range from food and dairy drying to pharmaceuticals, chemicals, tobacco, and grain processing.
All S&B IAH models are fully packaged, test-fired in our facility before shipment, and backed by our expert field service and extensive parts inventory.
Recirculating Indirect Fired Air Heaters (IAH-R)
Our IAH-R models are the highest-efficiency option in the S&B indirect lineup. By recirculating hot combustion gases on the burner side, these heaters can achieve thermal efficiencies up to 90% in a relatively compact footprint.
Key features and benefits include:
- Superior fuel efficiency and lower operating costs
- High-temperature capabilities (up to 900°F standard, higher available)
- Stainless steel construction options for corrosion resistance
- USDA Dairy Compliant configurations (IAH-R-USDA) for food-grade and sanitary processes
- Optional combustion air preheat (“economizer”) for even greater efficiency
- High-pressure designs available for demanding airflow conditions
The IAH-R is often the best choice for continuous-duty applications like spray drying or fluid bed drying where maximum efficiency and clean air are both priorities.
Non-Recirculating Indirect Fired Air Heaters (IAH-NR)
The IAH-NR delivers clean, combustion-free process air in a single-pass design. These units are typically smaller and more customizable than our recirculating models, making them an economical solution for many clean-air applications.
Highlights include:
- Straightforward installation and operation
- Excellent for medium-efficiency needs
- Highly customizable to exact process requirements
- Reliable performance in drying, curing, and chemical processes
- Compact footprint with robust construction
If your process requires clean hot air but doesn’t demand the absolute highest thermal efficiency, the IAH-NR often provides the ideal balance of performance and cost.
Straight-Through Indirect Fired Air Heaters (IAH-ST)
Our IAH-ST is the most space-efficient member of the family. As the name suggests, process air travels straight through the unit, resulting in a compact layout that fits tight installation spaces without sacrificing reliability or clean-air performance.
Notable advantages:
- Minimal footprint—ideal for retrofits or constrained plant layouts
- Clean, contaminant-free output
- Available in both horizontal and vertical configurations
- Recirculating or non-recirculating options within the straight-through design
- Lower operating costs compared to some non-recirculating alternatives
The IAH-ST is frequently selected when space is limited but the need for pure heated air cannot be compromised.
Choosing the Right S&B IAH Type for Your Process
Each S&B indirect air heater type shares the same foundational engineering: complete combustion isolation, heavy-duty heat exchangers, low-emission burner options, and custom configuration flexibility. The best choice depends on your priorities:
- Highest efficiency → IAH-R (including USDA versions) or IAH-ST
- High Temperature/ High Pressure → IAH-NR
- Smallest footprint → IAH-ST
Our engineers review your airflow, temperature rise, fuel type, emissions requirements, and space constraints to recommend the optimal solution—every time.
The Stelter & Brinck Advantage
With more than a century of process heat experience, we don’t just sell equipment—we deliver engineered products that perform reliably for decades. Every indirect air heater is custom-designed, thoroughly tested, and supported by responsive service.
Whether you need a USDA-compliant recirculating heater for dairy processing or a compact straight-through unit for chemical manufacturing, the S&B IAH family provides clean, 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 IAH type is right for your process? Drop a comment below or reach out directly—we answer every inquiry personally.