Modern make-up air systems must do more than replace exhausted air. Original equipment manufacturers (OEMs) are designing heating equipment that delivers consistent temperatures, dependable combustion, flexible installation options, and reliable performance across changing operating conditions.
As commercial and industrial ventilation requirements evolve, burner selection remains an important part of equipment design. Manufacturers need combustion solutions that can accommodate different airflow rates, heating capacities, equipment dimensions, and safety requirements without creating unnecessary engineering complications.
Midco International’s HMA direct-fired make-up air burner line continues to meet these demands through modular construction, advanced combustion technology, high turndown capabilities, and flexible system integration.
From commercial ventilation equipment and industrial facilities to automotive spray booths and process heating applications, Midco’s HMA burners provide OEMs with adaptable solutions for modern direct-fired heating systems.
Why Are Direct-Fired Make-Up Air Burners Still Important?
Make-up air systems replace air removed from buildings through exhaust fans, ventilation equipment, and industrial processes. Without sufficient replacement air, facilities can experience negative building pressure, temperature fluctuations, and ventilation performance problems.
Direct-fired make-up air burners heat incoming air by introducing combustion heat directly into the airflow rather than transferring heat through a heat exchanger.
This approach offers several advantages for appropriate commercial and industrial applications, including efficient heat transfer, responsive temperature control, and the ability to heat large volumes of outdoor air.
Common applications include manufacturing facilities, warehouses, commercial kitchens, industrial ventilation systems, automotive paint booths, and agricultural drying equipment.
For OEMs, the challenge is selecting a burner that provides the required heating capacity while maintaining stable combustion, acceptable emissions, and compatibility with the complete air-handling system.
What Makes Midco’s HMA Burner Line Different?
Midco International’s HMA burner family is designed specifically for direct-fired make-up air and related heating applications.
The product line includes the HMA-1 and the more advanced HMA-2 and HMA-2A series. While the HMA-1 remains supported for existing customers, Midco recommends the HMA-2A family for new applications.
The HMA-2 and HMA-2A burners use two-stage combustion technology to improve flame stability, control emissions, and provide greater flexibility across different operating conditions.
Unlike a conventional single-stage combustion arrangement, Midco’s two-stage design creates two distinct flames within the combustion zone. This helps produce a shorter, more stable flame while supporting cleaner combustion.
For equipment manufacturers, these characteristics can simplify burner integration and help address demanding heating and ventilation requirements.
How Does Two-Stage Combustion Improve Burner Performance?
Combustion stability is essential in direct-fired make-up air systems because airflow and heating demand can change during normal operation.
Midco’s HMA-2 and HMA-2A burners use two-stage combustion to improve control of the flame process and reduce carbon monoxide (CO) and nitrogen dioxide (NO₂) emissions.
Lower emissions are particularly important because direct-fired equipment introduces combustion products into the heated air stream.
The two-stage design also supports shorter flame lengths, which can provide additional flexibility when designing burner profiles and air-handling equipment.
For OEMs working with compact equipment cabinets or specialized duct configurations, this can be an important engineering advantage.
Actual combustion performance depends on burner configuration, airflow conditions, installation, and proper system testing.
Why Does High Turndown Matter in Modern Make-Up Air Systems?
Commercial and industrial heating equipment rarely operates at the same heating demand throughout the year.
Outdoor temperatures fluctuate, ventilation requirements change, and industrial processes may require different heating levels during operation.
A burner with a wide turndown range can adjust its firing rate to better match these changing conditions.
Midco’s HMA-2 and HMA-2A series can achieve turndown ratios of approximately 30:1 when equipped with appropriate modulation controls and gas valves.
This flexibility allows OEMs to design systems that provide high heating output when needed while operating at lower firing rates during reduced heating demand.
Benefits of effective burner modulation can include more consistent discharge temperatures, reduced unnecessary cycling, and improved control across varying operating conditions.
For modern make-up air equipment, high turndown is especially valuable when precise temperature control is required.
How Does Modular Burner Design Help OEMs?
One of the biggest advantages of Midco’s HMA burner line is its modular construction.
Rather than requiring a single fixed burner configuration, the HMA system uses interchangeable sections that can be assembled to meet different heating capacities and equipment layouts.
Available configurations include straight sections, elbows, tees, and back-inlet sections.
This allows OEMs to develop burner assemblies that fit a variety of cabinet dimensions, duct arrangements, and airflow requirements.
Modular construction can also simplify equipment design, component replacement, and inventory management.
For manufacturers developing multiple sizes of make-up air units, using a flexible burner platform can reduce the need to engineer an entirely different combustion arrangement for every product.
Midco also provides technical drawings and component information to support burner selection and integration.
Can Midco HMA Burners Handle High-Capacity Heating Applications?
Modern industrial make-up air systems may require substantial heating capacity, particularly when replacing large volumes of exhausted air during cold weather.
Midco’s HMA-2 and HMA-2A burner series provides firing capacities of up to 750,000 BTU/hr per linear foot under appropriate operating conditions.
Higher firing rates may be possible for certain process heating applications, depending on emissions requirements, equipment configuration, and engineering evaluation.
The HMA-2A series is also designed to operate across a differential pressure range of approximately 0.05 to 1.4 inches water column and air velocities of approximately 800 to 4,000 feet per minute.
These operating ranges give OEMs flexibility when integrating burners into different air-handling systems.
However, final burner sizing and performance must be evaluated based on the complete equipment design, including airflow, pressure drop, temperature rise, and combustion requirements.
How Do HMA Burners Support ANSI Compliance?
Safety and emissions requirements are major considerations for manufacturers developing direct-fired heating equipment.
Depending on the application, OEMs may need to design equipment around standards such as ANSI Z83.4, ANSI Z83.18, or ANSI Z83.25.
These standards address different categories of non-recirculating make-up air equipment, recirculating heating appliances, and direct gas-fired process air heaters.
Midco’s HMA-2 and HMA-2A combustion technology is designed to support the low-emissions performance needed for these applications.
Important considerations include carbon monoxide and nitrogen dioxide emissions, airflow monitoring, ignition reliability, flame supervision, temperature controls, and burner operating characteristics.
Although burner performance is an essential part of compliance, the complete heating appliance must satisfy the applicable standard.
Midco International also provides engineering assistance and in-house certification testing capabilities to help OEMs evaluate equipment performance and prepare for applicable certification requirements.
Where Are Midco HMA Burners Used?
The flexibility of the HMA product line makes it suitable for a wide range of commercial and industrial heating applications.
Commercial and Industrial Make-Up Air: HMA burners help heat incoming outdoor air used to replace air removed by building ventilation and exhaust systems.
Automotive and Industrial Spray Booths: Direct-fired heating systems provide temperature-controlled replacement air for painting, finishing, and certain curing operations.
Manufacturing and Process Heating: Industrial facilities can use direct-fired burner systems for applications requiring controlled heated airflow.
Agricultural and Grain Drying: HMA burners can support drying applications where large volumes of heated air are required.
Loading Docks and Air Curtains: Heated make-up air can help address cold outdoor air entering facilities through frequently opened doors and loading areas.
Each application has different airflow, temperature, emissions, and safety requirements. Proper burner selection and equipment integration are essential for reliable performance.
Why Is Burner Integration Important for OEMs?
Even a well-designed burner must be correctly integrated into the complete heating system.
Burner placement, airflow distribution, pressure drop, profile opening dimensions, and control system selection all influence combustion performance.
For example, pull-through systems position the burner upstream of the blower, allowing the blower to help mix heated air. Push-through configurations position the burner downstream of the blower and may require additional attention to temperature distribution.
The burner profile must also be designed to maintain the airflow conditions required for stable combustion.
Midco works with OEM engineering teams to evaluate these factors and develop burner configurations suited to their equipment.
Early engineering collaboration can help manufacturers address potential performance concerns before moving into production or certification testing.
Frequently Asked Questions About Midco HMA Burners
What is the difference between Midco HMA-1 and HMA-2A burners?
The HMA-1 is Midco’s original direct-fired make-up air burner platform, while the HMA-2A incorporates advanced two-stage combustion technology for improved flame stability, emissions control, and operating flexibility. Midco recommends the HMA-2A product family for new applications, while HMA-1 information remains available for existing customers.
What is the maximum heating capacity of an HMA-2A burner?
The HMA-2A series can provide up to 750,000 BTU/hr per linear foot under appropriate operating conditions. Total heating capacity depends on burner assembly length, configuration, airflow, and application requirements.
Can Midco HMA burners be customized for different equipment sizes?
Yes. The modular design allows OEMs to combine straight, elbow, tee, and inlet sections to create burner assemblies suited to different cabinet dimensions and heating capacities.
Are HMA burners suitable for industrial process heating?
Yes. Midco HMA burners are used in various industrial applications, including drying equipment, spray booths, and specialized process heating systems. The burner configuration must be evaluated against the application’s temperature, airflow, and safety requirements.
Do HMA burners support natural gas and propane?
Yes. Midco’s HMA burner line supports natural gas and propane applications. The HMA-2A platform can also accommodate certain butane applications when reviewed with Midco’s engineering team.
Can Midco help OEMs with burner selection and certification testing?
Yes. Midco International provides engineering assistance, burner customization, combustion evaluation, and in-house product certification testing support. Working with Midco early in equipment development can help manufacturers select an appropriate burner configuration and address applicable performance requirements.
Why Choose Midco International for Modern Make-Up Air Burner Solutions?
Modern make-up air equipment requires a balance of heating capacity, combustion performance, flexibility, and dependable operation.
Midco International’s HMA burner line continues to provide OEMs with practical solutions through advanced two-stage combustion technology, modular configurations, high turndown capability, and engineering support.
With decades of combustion engineering experience and manufacturing operations in Chicago, Illinois, Midco works with equipment manufacturers developing commercial ventilation systems, industrial make-up air units, spray booths, and process heating equipment.
Our team understands that every OEM application has different heating requirements, equipment dimensions, airflow conditions, and certification considerations.
Contact Midco International today to discuss your make-up air burner requirements, explore our HMA-2 and HMA-2A solutions, and learn how our engineering team can support your next equipment design.