Specification Manual

STERLING “XF” SERIES CONVERTIBLE VENTING TYPE
TUBULAR PROPELLER UNIT HEATER
XFS-1
PROJECT:
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DESCRIPTION
The Sterling “XF” Series Convertible Venting Type Tubular Propeller Gas-
Fired Unit Heater offers a highly efficient, extremely durable alternative to
the traditional clam shell design. These propeller type units combine the
latest tubular heat exchanger and in-shot burner technology with the
quality and reliability you have come to know from Sterling. Units are
available in sizes 100 to 400 MBH and have been certified by ETL as
providing 83% thermal (combustion) efficiency.
CONVERTIBLE VENTING - STANDARD OR SEPARATED COMBUSTION
Notably, the Sterling “XF” unit heater is designed so it can be installed
in either standard or separated combustion venting configurations
without requiring modification to the unit itself. Located on the rear
cover panel of each unit, combustion air inlet collars are left open in a
standard combustion venting configuration. When set up for separated
combustion, combustion air piping is connected to the inlet collars so
that the burners, spark ignitor, and flue system are enclosed within the
unit, allowing the entire combustion process to remain unaffected by
the atmosphere in the space where the heater is located. Separated
combustion venting configurations should be used where dusty, dirty
or mildly corrosive conditions exist, or where high humidity or slightly
negative pressures prevail.
ADDITIONAL VENTING FLEXIBILITY
The Sterling “XF” unit heater is ETL certified in accordance with categories
I and III venting requirements. This certification allows units to be vented
both vertically and horizontally using either single wall or double wall
venting materials. Available as an accessory option, Sterling offers a
Combustion Air Inlet Kit that allows for concentric venting of both
combustion and exhaust air systems through one termination.
TUBULAR HEAT EXCHANGER
The Sterling 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 Sterling tubular heat exchangers are
constructed of heavy duty 20-gauge aluminized steel. Optional 409
stainless steel heat exchangers are also available.
DIRECT SPARK IGNITION SYSTEM & CONTROL ACCESSIBILITY
Sterling “XF” 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. Designed with the service person
in mind, ignition and fan controls are located in one centrally located
control panel.
CAUTIONS
Combustion air and vent systems must be installed in accordance with
current National Fuel Gas Code or Installation Code, Installation Code for
Natural Gas Burning Appliances and Equipment (Canada) and any local
and state codes. Units should not be installed where negative pressures
are significant, where vapor containing chlorine or fluorine may be present
or in any areas classified as "hazardous."
STANDARD FEATURES
• Designed for either standard or separated
combustion
• 20-gauge aluminized steel tubular heat
exchanger
• 83% thermal efficiency
• ODP propeller motor (with overload protection)
• Power venter
• Combustion air pressure switch
• 20-gauge steel cabinetry with baked enamel
finish
• Direct spark ignition system
• 115/24 volt control transformer
• 115/1/60 supply voltage
• Redundant single stage gas valve
• Rear access to in-shot burners
• Individually adjustable and removable
horizontal louvers
• Complete fan guard
• Main control panel
• 10 year heat exchanger, flue collector and
burner warranty
OPTIONAL FEATURES
• Stainless steel heat exchanger, burners, and/
or flue collector
• Two stage and various electronic modulation
gas controls
• Discharge nozzles (30°, 60° & 90°)
• Combustion air inlet kits (allows concentric
venting with horizontal or vertical termination)
• TE propeller motor
• Supply voltages: 208 & 230/1/60 and 208,
230, 460, 575/3/60
260 North Elm St., Westfield, MA 01085
[phone] Fax: [phone]
www.sterlinghvac.com
08/19