Your browser is out of date.

You are currently using Internet Explorer 7/8/9, which is not supported by our site. For the best experience, please use one of the latest browsers.


Custom Engineered Direct Inject Heating

Custom Engineered Direct Inject Heating. Harness your central heating and add precise control of temperature and flow rate in one or more hot oil sub-loops.

DIO Series Custom Engineered Direct Inject Heating Hot Oil Systems offer Safe Reliable Performance in an industrial-grade system that takes advantage of your facility’s central heat source to precisely control temperatures in a specific secondary sub-loop of your process using the direct injection of hot oil. 

Allowing for accurate temperature control that cannot be obtained with variable flow rates, the DIO Series Temperature Control Units offer a better alternative for applications that require flow rates higher than available from the central system or that require precise temperature control and/or heating and cooling. DIO Series are designed for use with available existing hot oil central heating sources, with maximum operating temperatures up to 750°F.  Capable of using up to 600 Volt, 3-Phase, 50/60 Hz power capabilities, and heating capacities of up to 10 MM Btu/Hr. If an existing hot oil central heating source is not available, combine with one of HEAT’s SL or GFO Series hot oil systems to provide the necessary heating capacity needed. 

Our engineering team will work with you to design a system based on your unique process or application. DIO Series systems typically include a Circulating Pump, Heating Circuit, Cooling Circuit, Expansion Tank, and Control Panel. These units are constructed with all-welded Carbon Steel or Stainless-Steel wetted materials, insulated with Non-Wicking Cellular Glass Insulation, and assembled on a drip-proof, seal-welded plate-and-channel fluid containment base. 

HEAT offers four distinct levels of customization, ranging from minimal customization to fully built-to-specification designs. Each unique system undergoes a Factory Acceptance Test in accordance with HEAT standard practice prior to shipment. 

Why Custom Design?


  • Maximum Operating Temperatures up to 750°F
  • Direct Inject Thermal Fluid Heating
  • Heating Capacities Up to 10MM Btu/hr. and Higher
  • Up to 600 VAC, 3-Phase, 50/60Hz Power Capabilities
  • General Purpose and Hazardous Area Designs
  • Design Temperatures of 450°F, 550°F, 650°F, and 750°F 
  • 4 Levels of Customization
  • Indoor/Outdoor installation
  • Heat Only & Heat/Cool Designs Available
  • Uses thermal fluid from a central fluid system as a heat source
  • Fluid Maintenance & Sampling Ports
  • Seller standard or Custom Paint Colors 
  • Centrifugal and positive displacement (PD) options
  • Mechanical and Seal-less designs
  • Air- and water-cooled pump designs
  • Single and dual pump configurations 
  • Direct inject thermal fluid from an external central fluid system
  • Heat Input controlled by a Proportional Control Valve 
  • Integral and modular designs
  • TEMA / ASME exchanger designs available
  • Air-to-Oil and Water-to-Oil cooling options available
  • Proportional and on/off control  
  • Top mounted and remote mounted designs
  • Single and double expansion line designs
  • Non-pressurized and pressurized configurations 
  • ASME U/UM designs available 
  • Welded and flanged construction
  • Carbon steel and stainless steel available
  • ASME B31 Piping Materials 
  • Skid mounted and remote mounted control panels
  • Digital PID Temperature Control or Remote Operation Control
  • Configurations for external control from PLC, DCS or other external control 
  • NEMA 4, NEMA 4X, NEMA 12, NEMA 7, Class I, Division I and Class I, Division 2 
  • NFPA 87, NFP70, NFPA 79, NEC, UL, cUL, CSA 

Heat Systems: Safe by Design

Learn more about our Standard Design Practices for Custom-Engineered Hot Oil Systems
Learn More
Have Questions?

Contact Our Experts

Our expert sales engineers can help you find the right custom temperature control equipment for your application.

*denotes a required field.