Indirect Fired Firecage Heaters


  • U500 (500,000 Btu/hr Duty) 
  • U750 (750,000 Btu/hr Duty)
  • U1000 (1,000,000 Btu/hr Duty)
  • U1500 (1,500,000 Btu/hr Duty)
  • U2500 (2,500,000 Btu/hr Duty)
  • U3500 (3,500,000 Btu/hr Duty)
  • U5000 (5,000,000 Btu/hr Duty)


  • Custom engineered larger indirect fired Utherm heaters available on request
  • Custom Utherm heaters available on request

Unsurpassed efficiency is achieved with our Firecage heating system. Our indirect fired heaters can obtain 80% to 95% LHV efficiency levels depending on process temperature. Lower your environmental footprint without sacrificing performance thanks to Utherm indirect fired heaters.

Typical process applications for our Utherm indirect fired heaters include indirect gas heating, fuel oil heating, amine reboiling, hot oil heating, condensate stabilizer reboiling, heat medium heating, heater treating, steam generating, remote tank heating and glycol reboiling.


The Utherm indirect fired heater combines the proprietary Utherm Firecage, helical process coil, and a natural gas radiant metal matrix burner. Indirect fired heaters can be installed outside, do not require a burner building, and runs on minimal electricity. Utherm indirect fired heaters are available ranging from 250,000 Btu/hr to 5,000,000 Btu/hr and can be combined in a parallel configuration to meet elevated heat and/or flow rate requirements.

  • The Firecage is our unique design for optimizing heat transfer to a process while maximizing efficiency and minimizing package footprint. A conventional bath heater has a thermal efficiency 65-75% LHV, and our proprietary design allows thermal efficiencies of up to 94%, offering significant fuel savings.
  • The helical coil is designed to transfer heat from the heat medium to the process using a tightly spaced helix of heavy wall piping. This configuration allows the design to maximize surface area and provide even distribution to the process piping. Each of our coils is designed and registered specifically for the end user.
  • The burner assembly includes the Utherm proprietary ultra low emission radiant metal matrix burner (<30 ppm NOx) which heats the heat medium, providing even heat transfer/flux to the Firecage. The burner is a natural draft, minimizing electrical consumption and allowing the whole package to run on 24 VDC or 120 VAC. Packages can be provided with high energy or high voltage ignition, and a flame rod or flame scanner for flame detection.

Utherm indirect fired packages can be customized to meet process requirements, customer specifications, and governing codes. 

When the process fluid is considered to be flammable, the indirect fired heater is the best option due to the separation of the burner from the process fluid coil.

Typical process applications for Utherm heaters include but are not limited to an indirect gas heater, fuel oil heater, amine reboiler, hot oil heater, condensate stabilizer reboiler, heat medium heater, heater treater, steam generator, remote tank heater and glycol reboiler.

Indirect/Direct Fired Heater


  • Process heating coil, heat exchanger, flame arrestor, and burner can be easily removed for inspection, maintenance, and cleaning. 
  • The fuel train and controls are easily accessible on the front of the heater cabinet. 
  • The fuel/air mixers, burners, and ignition systems are all easily accessible by removing the bolts on required panels.

Utherm Heater VS Bath Style Heater

Heater DiameterUtherm1.2mOther1.1m
Heater LengthUtherm1.2mOther3.7m
Heater HeightUtherm2.0mOther1.2m
Efficiency (LHV)Utherm93%Other75%
Fluid VolumeUtherm120 litresOther2000 litres
Dry WeightUtherm1500kgOther3000kg
Filled WeightUtherm1620kgOther5000kg
Radiant Surface AreaUtherm3.2m² Other2m²
Average Radiant Heat FluxUtherm45kW/m² Other80kW/m²

Tech Specs

AOverall HeightU750250 inU1000254 inU1500260 inU2500272 in
BWidthU75057 inU100064 inU150064 inU250084 in
CDepthU75086 inU100090 inU150090 inU2500109 in
DFlange ElevationU750115 inU1000119 inU1500125 in U2500139 in
SNominal Stack DiameterU750NPS 8U1000NPS 12U1500NPS 12U2500NPS 12
N1Process Inlet ConnectionU750NPS2-CL600RFWNU1000NPS2-CL600RFWNU1500NPS2-CL600RFWNU2500NPS4-CL1500RFWN
N2Process Outlet ConnectionU750NPS2-CL600RFWNU1000NPS2-CL600RFWNU1500NPS2-CL600RFWNU2500NPS4-CL1500RFWN
N3Fuel Inlet ConnectionU750NPS1-CL150RFTHU1000NPS1-CL150RFTHU1500NPS1-CL150RFTHU2500NPS1-CL150RFTH
Minimum Process DutyU7500 MMBtu/hrU1000750 MMBtu/hrU15001000 MMBtu/hrU25001500 MMBtu/hr
Maximum Process DutyU750750 MMBtu/hrU10001000 MMBtu/hrU15001500 MMBtu/hrU25002500 MMBtu/hr

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