Tubular Duct Furnace

Designed for use with existing systems for any ducted air application, the TD Series duct furnace is the latest addition to the tubular product line. Coupled with Sterling's "In-Shot" burner technology, TD units are built for superior durability, reliability and performance. Units are available in 7 sizes (100-400 MBH) and offer industry leading efficiencies with a limited 10-year heat exchanger warranty.

The TD duct furnace is designed so that it can be easily field converted to separated combustion using the optional "Air Inlet Kit" or "Combustion Air Inlet Kit". The unit can also be easily converted from right to left hand without requiring any additional parts.

Standard Features

  • 100 - 400 MBH
  • 82% Thermal Efficiency
  • In-Shot Burner Design
  • 20-Gauge Steel Jacket with Baked Enamel Finish
  • Double Wall Construction
  • 115/1/60 Supply Voltage
  • Direct Spark Ignition
  • Redundant Single-Stage Gas Valve
  • 115/24 Volt Controls transformer
  • Power Vented
  • 20-Gauge Aluminized Steel Heat Exchange
  • Natural or Propane Gas
  • 10 Year Heat Exchanger, Flue Collector and Burner Warranty
  • Four Point Suspension
  • Easy Access Control Panel
  • Left Hand Control Access – Field Convertible to Right Hand

Tubular Heat Exchanger

The Sterling HVAC tubular heat exchanger has been designed to provide maximum and uniform heat transfer. The low-pressure drop associated with this design enables heated air to be evenly distributed to the conditioned space. This curved, non-welded serpentine design experiences less thermally induced stress making it highly durable for significantly longer service life. All standard Sterling HVAC tubular heat exchangers are constructed of heavy duty 20-gauge aluminized steel with an optional 409 stainless
steel heat exchanger available for applications in mildly corrosive environments

    Direct Spark Ignition System

    Sterling HVAC TD units utilize a direct spark pilotless ignition of the burner, providing fast heat delivery. This highly reliable and efficient ignition system incorporates an integrated electronic control board to regulate the system sequence of operation, including an externally mounted LED indicator for simple troubleshooting.


      The Sterling HVAC TD Series is ETL certified in accordance with category III venting requirements. This certification allows units to be vented both vertically and horizontally using either single wall or double wall venting materials. This venting flexibility of the TD duct furnace makes installation easier and more cost effective by allowing the installer to utilize existing venting components. The TD duct furnace can be field converted to separated combustion using the “Air Inlet Kit” or the “Combustion Air Inlet Kit”. This is recommended for units to be installed in dusty, dirty or mildly corrosive environments or where high humidity or slightly negative pressures exist. All critical components including the burners, direct spark ignition, and controls are fully enclosed within the unit and protected from the elements ensuring clean and efficient combustion.

        Control Accessibility

        Designed with the service person in mind, every component of the Sterling HVAC TD Series is easily accessible. Ignition and fan controls are located in one centrally located control panel. The access panel provides control isolation as well as a pleasing exterior appearance.


          All the Literature associated with the TD Series


          For additional items browse the full Literature library at the link below.


          Performance, Materials and Features for each TD Series capacity model.









          MBH Input100 MBH150 MBH200 MBH250 MBH300 MBH350 MBH400 MBH
          MBH Output82 MBH123 MBH164 MBH205 MBH246 MBH287 MBH328 MBH
          Thermal Efficiency82%82%82%82%82%82%82%
          Air Temp Rise30°F - 100°F30°F - 100°F30°F - 100°F30°F - 100°F30°F - 100°F30°F - 100°F30°F - 100°F
          Min CFM758 CFM1,137 CFM1,517 CFM1,896 CFM2,275 CFM2,654 CFM3,034 CFM
          Max CFM2,528 MBH3,792 MBH5,057 MBH6,321 MBH7,585 MBH8,849 MBH10,114 MBH
          Pressure Drop0.65.44.540.760.690.760.70


          The TD Series is quite versitile it can be installed in a variety of applications. Here are a few key ways The TD Series can make your space more comfortable.

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