Direct Fired Firecage Heaters

The direct fired heater traps flue gases through our innovative Firecage to achieve 80% to 95% LHV efficiency. An ultra low emissions burner (<30ppm NOx) heats the process fluid inside of the Firecage. Due to the small diameter of the fin tubes in the upper half of the Firecage, this heater is best used for low pressure applications. An ideal application for this heater is as a water boiler. 

With flammable substances, the indirect fired Firecage heater is the best option due to the separation of the burner from the process fluid coil.




  • Rated for Class I Division II hazardous areas 
  • Touchscreen HMI display for simple operation
  • Modulation of burner firing rate (up to 7:1 turndown) fixed ratio fuel/air mixers with no secondary air for high efficiency at all firing rates

Utherm VS Bath

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/m²Other80kW/m²

Tech Specs

AOverall HeightU750236 inU1000236 inU1500236 inU2500238 in
BWidthU75057 inU100064 inU150064 inU250084 in
CDepthU75086 inU100090 inU150090 inU2500109 in
DFlange ElevationU750101 inU1000102 inU1500101 inU2500123 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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