Indoor Gravity-Vented Gas-Fired Duct Furnace

• ETL certification for commercial and industrial use in the US and Canada.
• Aluminized steel cabinet with duct flanges for easy ductwork connection.
• 81% minimum thermal efficiency over a 20 to 100°F temperature rise range for fuel savings.
• Patented aluminized-steel dimple-tube clamshell heat exchanger for maximum heat transfer (409 stainless steel optional).
• Blocked vent safety switch to verify proper venting
• Gravity vented with a 45° angled round vent connection for tighter ducting
• Heat exchanger certified to withstand 3.0″ W.C. external static for use in systems with long duct runs or high static accessories.
• Aluminized steel burner with stainless steel separator strip (409 stainless steel optional).
• Right-hand control access (left hand optional) with slide-out burner access.
• Single-stage gas controls (two-stage, electronic modulation, or building management controls using a 0-10 Vdc or 4-20 mA input, optional).
• Automatic reset high limit safety control (manual reset optional).
• Intermittent pilot ignition with the continuous retry control system.
• Control the terminal board and low-voltage terminal connections.
• Gas control step-down transformer with 24V gas controls.
• 4-point mounting with threaded rod (by others).
• Designed, Engineered & Assembled in the USA

Factory-Configured & Installed Options

• Input Capacities:
  • 100, 125, 150, 175, 200, 225, 250, 300, 350, or 400 MBH

• Heat Exchanger, Burner, & Drip Pan Material:
  • All 409 Stainless Steel

• Control Stage Designation:
  • Single Stage
  • 2-Stage / Modulating

• Access Side:
  • Left-Hand
  • Right-Hand control/piping access

• Gas & Ignition Configuration:
  • Natural Gas with Continuous Retry Ignition Controller
  • Propane Gas with Lockout Ignition Controller

• Gas Valve Options:
  • Single Stage
  • Two Stage
  • Electronic Modulation
  • Electronic Modulation Primary (for multiple-furnace setups)
  • Electronic Modulation Secondary (for multiple-furnace setups)
  • Electronic Modulation with 0–10 VDC external input signal

• Safety Switches:
  • Standard or Premium Control Box (no additional gas pressure switches)
  • High & Low Gas Pressure Switch (Premium Control Box option)

• Supply Voltage:
  • 115V/1Ph, 208V/1Ph, 230V/1Ph, 208V/3Ph, 230V/3Ph, 460V/3Ph, or 575V/3Ph (60Hz)

• Control Power Transformer:
  • None, 40 VA, 75 VA, or 150 VA

• Factory-Installed Control Devices:
  • Airflow Proving Switch (Differential pressure switch)
  • Timed Freeze Protection (Includes low discharge thermostat and freeze protection timer)
  • Supply Air Fire Stat (Shuts system down if local temperature exceeds 200°F)
  • Control Relay (Double-Pole, Double-Throw)
  • Time Delay Relay (Delays blower start for heat exchanger warm-up)
  • Factory-Installed Duct Thermostat (Honeywell T678A1015 shipped with ductwork sensing tube)

Field-Installed Accessories

• Thermostats, Sensors, & Adjusters:
  • Single-Stage Heat Only Room Thermostat (without switching)
  • Single-Stage Heat and Cool Room Thermostat (with switching)
  • Two-Stage Digital Non-Programmable Heating Room Thermostat (with switching)
  • Two-Stage 7-Day Programmable Room Thermostat (White Rodgers)
  • Duct Thermostat: Johnson Controls Electronic Temperature Control (with field-installed temperature sensor and dual relay module)
  • Duct Thermostat: Honeywell T678A1015 (Field-installed version with sensing tube)
  • Maxitrol Electronic Modulating Discharge Air Sensor & Mixing Tube (55°–90°F or 80°–130°F range)
  • Maxitrol Set Point Adjusters (TD121 or TD121A)
  • Maxitrol Room Override Thermostat (T115, 40°–90°F range)

• System Controls & Components:
  • 7-Day Electronic Programmable Time Clock
  • Mild Temperature Thermostat (Dual relay with inlet air temperature sensor)
  • Photoelectronic Duct Smoke Detector (For 0.5–2.5 ft or 2.5–5.0 ft duct widths)
  • Natural Gas Pressure Regulator
  • Summer/Winter Switch (Double-pole, double-throw switch to disable heating in summer)

• Mounting & Condensate Hardware:
  • Pipe Hanger Kit (4 adapters per kit to adapt hanger points to pipe suspension)
  • Drain Connector Kit (Connects drain line to the condensate drain pan)

• Fuel Conversion Kits:
  • Natural-to-Propane Gas Conversion Kit

Ideal for providing heated supply air in commercial and industrial environments, the DFG series is designed for use with standard air handling systems in air conditioning, heating, or makeup air applications. Common applications include:

• Commercial Office Buildings
• Institutional Facilities
• Mechanical rooms
• Gymnasiums
• Multi-Purpose Rooms
• Cafeterias / Kitchen Hoods
• Lab Exhaust Hoods
• Bathroom / Locker Rooms
• Paint / Welding Booths