Steam Boilers (“H” series and “S” series)

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The AJAX Series Steam Boilers .boast the same advantages as other Ajax boilers: dependability, quiet operation and long life.Inclined tubes provide uniform heat transfer, resulting in high fuel economy and long boiler life. 2″ O.D. tubes (steel or copper) are rolled into large headers on both ends producing excellent boiler circulation. 2″ O.D. tubes are less restrictive than smaller O.D. tubes. Our non-proprietary tubes are less costly for tube replacement. Ajax’s straight tube design allows for easy inspection of tube conditions. 


Full access to water sections, steam drum and combustion chamber, all models are ETL listed for natural gas or propane.  ETL  listed outdoor models available for non-freezing applications. 





Water Tube Bundle Assembly

Constructed and Stamped to ASME Code, the water tube assembly is individually rolled into the headers and supported by a rugged steel frame with expansion joints at each corner. This allows the entire tube bundle to float freely as it expands and contracts preventing thermal shock damage. The elimination of air bubbles and the prevention of waterside corrosion is accomplished by sloping the tubes upward 1/2″ per linear foot from the rear to the front. 

Atmospheric Burner Assembly

Multiple burner heads make up the burner assembly, each with its own venturi and orifice. The cast-iron burner head has long been recognized as the simplest, most trouble-free gas burner available. 

Pre-Mix / Low NOx Burner Assembly

Ajax boilers use proprietary 9 and 12 ppm NOx burner assemblies that combine simple design and long-term reliable service. The low NOx is achieved by using a perforated burner plate, gas injector, and a low energy gas-air mixing sections in a clean manifold design. 

Highlights: SR & HR series

  • Burner Design: Standardized across product lines
  • Heat Exchanger: Increased surface area means greater efficiency
  • Efficiency: 83% (atmospheric) / 84% – 85% (forced draft)
  • Size: Lower height due to reduced size of combustion chamber