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Combat® UHA[X][S]-Series
Axial Fan Tubular Unit Heaters
Equipment
Specications
1.800.828.7450
www.rg-inc.com
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GAS-FIRED UNIT HEATER GUIDE SPECIFICATION
PART 1 GENERAL
Provide gas-red unit heaters, designed and manufactured for
indoor use.
1.1 SECTION INCLUDES
A. Unit Heater
B. Controls
1.2 REFERENCES
A. American National Standards Institute (ANSI) / Canadian
Standards Association (CSA): Establish requirements applicable
to construction, certication and installation of unit heaters.
a. Standard ANSI Z83.8 / CSA 2.6 “Gas Unit Heater and Gas-
Fired Duct Furnaces” (latest edition)
B. IAS: Establishes requirements applicable to construction and
certication of unit heaters.
a. Standard No.10-96 “Unit Heaters for Residential Use”
(latest edition)
C. National Fire Protection Association (NFPA): Establishes re
prevention standards.
a. Article 54: National Fuel Gas Code (latest edition)
b. Article 70: National Electric Code (latest edition)
1.3 SUBMITTALS FOR REVIEW
A. Product Data: Provide data with dimensions, service
connections, accessories, controls, electrical nameplate data and
wiring diagrams.
1.4 PROJECT CLOSEOUT PROCEDURES
A. Training: Provide owner with verbal operating instructions as
well as original manufacturer’s installation, operation and service
manuals.
1.5 QUALITY ASSURANCE
A. Manufacturer Qualications: Company specializing in
manufacturing the products specied in this section (gasred unit heaters) with a minimum of ten years documented
experience. Equipment shall be the standard product of the
manufacturer and shall have complete catalogued data.
B. Installer Qualications: All installation and service of unit
heaters must be performed by a contractor qualied in the
installation and service of said products with proof of a
minimum of three years documented experience.
C. Factory Testing: Each unit heater shall be factory tested. Testing
shall consist of verication of correct operation of burners,
manifold, control assembly and electrical components.
1.6 REGULATORY REQUIREMENTS
A. Conform to ANSI Z83.8 / CSA 2.6, latest edition, and provide
evidence that the unit heater and its control system have been
found in compliance with these standards by a nationally
recognized testing laboratory.
1.7 WARRANTY
A. e product shall have a manufacturer’s limited warranty of at
least 24 months, subject to the manufacturer’s standard warranty
limitations.
PART 2: PRODUCTS
2.1 MANUFACTURERS
A. COMBAT® by Roberts-Gordon UHA[X][S]-Series
2.2 MANUFACTURED UNITS
A. Unit: Gas-red, power-vented unit heater with tubular heat
exchanger. Units shall have a minimum of 82% thermal
eciency. e standard unit shall consist of a non-separated
combustion design with an aluminized heat exchanger. Design
and heat exchanger alternatives shall be oered as follows:
1. Separated Combustion: A separated combustion unit shall
consist of an enclosed sealed burner box to which
combustion air is vented through a piece of internal exible
air duct. is duct terminates at an exterior cabinet ange to
which a vent run to the outside of the heated space should be
attached.
2. Stainless Steel Heat Exchanger: A stainless steel heat
exchanger unit shall consist of heat exchanger tubes, heat
exchanger tube supports, heat exchanger tube plates and a
vent box produced of 409 stainless steel.
2.3 FABRICATION
A. Casing and Components: Galvannealed steel panels, minimum
20 gauge. All panels shall be lined with a minimum of
3/8"(10mm) thick insulation.
B. Access Door: Door shall be provided for easy service of all
critical components.
C. Finish: Standard nish is a heavy-duty white powder-coat.
D. Louvers: e cabinet shall be equipped with horizontal louvers.
Louvers shall be spring-held and adjustable for directing airow.
2.4 HEAT EXCHANGERS, BURNERS AND GAS TRAIN
A. Heat Exchangers: For Models 30-125, heat exchanger tubes
shall be of a six-pass design with 1.5" (38 mm) outer diameter
[aluminized steel] [409 stainless steel] tube. For Models 150400, heat exchanger tubes shall be of a four-pass design with
1.75" (44 mm) outer diameter [aluminized steel] [409 stainless
steel] tube. Heat exchangers shall not be clamshell design. For
Models 150-400, the heat exchanger tubes shall be dimpled to
provide ecient heat transfer. e tube plates shall be made of
[aluminized steel] [409 stainless steel]. e tube supports shall
be made of [galvannealed steel] [409 stainless steel].
B. Burners: e burners shall be in-shot type, directly ring each
heat exchanger tube individually. Burners shall be capable of
burning natural gas or LPG.
C. Gas Train: e gas train is constructed of black pipe and includes
a single-stage gas valve. e valve provides the regulator, main
gas and manual shuto functions.
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2.5 COMBUSTION AIR AND VENTING COMPONENTS
A. Vent Box: e vent box shall be of [aluminized steel] [409
stainless steel].
B. Flue Fan: Each unit shall have a factory-installed ue fan to draw
combustion gases through the heat exchanger and into the ue
venting. No unit shall be gravity vented. e ue fan shall be
internally mounted by the manufacturer. No combustion dra
inducers shall be mounted outside of heater cabinet.
C. Combustion Air: For non-separated units, the combustion
air shall be drawn into the unit's exposed burner box directly
from the heated space through openings in the access door. For
separated units, the combustion air shall be drawn from outside
the heated space into the unit's enclosed burner box through
a piece of exible duct that terminates at an exterior cabinet
ange. Ductwork shall be run from that ange to the building
penetration.
D. Flue and Combustion Air Connections: e ue collar and
combustion air collar (if applicable) shall be located on the rear
of the unit. For Models 30 - 125, heater design shall allow for the
shiing of the venting and combustion air collars to the top of
the cabinet in the eld.
2.6 AXIAL FAN
A. Fan: Each unit is supplied with one (Models 30-250) / two
(Models 300-400) axial fan(s).
B. Fan Guard: Each axial fan is covered with a fan guard. e
guard shall protect against objects ½" (12 mm) and greater in
diameter.
C. Motor: e motor shall be an open drip-proof (ODP), standard
eciency design, wired for 120 V/ 1 Ø / 60 Hz. e motor shall
be shaded pole (SP) (Models 30 - 75) / permanent split capacitor
(PSC) (Models 100 - 400).
control terminal shall allow for 2-wire heating control or 4-wire
heating and “fan only” control.
2.8 OPTIONS AVAILABLE
(Select Applicable Options)
A. Shelf-Mounting Bracket Kit (Available for Models 30-125 Only):
e shelf-mounting bracket kit shall provide a manner in which
to mount a unit to an existing shelf.
B. Wall Suspension Mounting Bracket Kit (Available for Models
30-125 Only): e wall suspension mounting bracket kit shall
provide a wall-mounted structure from which a unit can be
suspended.
C. Wall Shelf Mounting Bracket Kit (Available for Models 30-125
Only): e wall shelf mounting bracket kit shall provide a wallmounted shelf structure on which a unit can be mounted.
D. Vertical Louver Kit (Available for Models 30-125 Only): e
vertical louver kit shall provide a means to control horizontal air
ow.
E. Concentric Vent Kit: e concentric vent kit allows the ue
and combustion air to be consolidated into a single concentric
vent, thereby minimizing the number of required wall/roof
penetrations. e kit consists of a concentric vent box, a 4" (101
mm)vent terminal with bae plate and a 6" (152 mm) (Models
30-250) / 8" (203 mm) (Models 300-400) combustion air
terminal.
F. Fuel Conversion Kit: e fuel conversion kit allows for
eld-conversion of the type of gas supplied to the unit. e
kit consists of a replacement spring for the gas valve and
replacement orices.
2.7 CONTROL SYSTEM
A. Factory Testing: e complete control system and burner
and gas manifold functions shall be factory tested for proper
operation and to simplify eld commissioning.
B. Control Enclosure: Burner controls (transformer, ignition
module, gas valve, safety switches) shall be internally
mounted by the manufacturer. No burner controls or gas train
components shall be mounted outside of heater cabinet.
C. Safety Controls:
1. Air Flow Switch: e air ow switch measures air pressure
dierential across the heat exchangers to verify blower
operation and the presence of an adequate supply of
combustion air. e gas valve cannot open until the air ow
switch is satised.
2. High Temperature Limit Switch: e high temperature limit
switch shall turn the burners o when air is discharged above
its set point. e switch ensures unit shut down in case of
axial fan failure or any problem which may result in
overheating.
D. Controls System: Units shall be equipped for use with 120 V /
1 Ø / 60 Hz power supply. All units shall be factory equipped
with a 24 V thermostat control terminal strip on the outside of
the cabinet, pre-wired to heater internal controls. ermostat
2.9 PERFORMANCE
A. See Schedule on plans.
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PART 3: EXECUTION
3.1 INSTALLATION
A. General: Install gas-red unit heaters as indicated, in
accordance with manufacturer's installation instructions
and in compliance with applicable codes and approvals.
Allow adequate space for combustion air supply, circulation
(axial) fan air supply, servicing or removal of the unit
without disturbing other equipment. For installation at
altitudes above 2,000' (610 m), inform manufacturer at time
of order for appropriate high altitude adjustment and rating
by the manufacturer.
B. Support: Suspend heater, venting, gas piping and conduit
from building substrate as indicated, or if not indicated, in
a manner to provide durable and safe installation; and in
accordance with manufacturer's installation instructions.
Recommended mounting heights shall be measured from
oor level. Models 30 - 45 shall have a recommended
mounting height of 12' (3.7 m). Models 60 - 75 shall have
a recommended mounting height of 15' (4.6 m). Models
100 - 175 shall have a recommended mounting height of
20' (6.1 m). Models 200 - 250 shall have a recommended
mounting height of 25' (7.6 m). Models 300 - 400 shall have
a recommended mounting height of 30' (9.1 m).
C. Clearances to Combustibles: Do not impede upon
clearances to combustibles outlined and printed on burner
nameplate, and in manufacturer's product data. Measure
clearances distance from surface of cabinet. Models 30125 shall have a rated clearances to combustibles of 0"
(0 cm) below unit and not to exceed 1" (2.54 cm) above
the unit. Models 150-400 shall have a rated clearances to
combustibles of 3" (7.62 cm) below unit and 6" (15.24 cm)
above the unit.
D. Venting: Install vent piping as indicated and per national
and local codes. Terminate where indicated with vent
terminal assembled per instructions supplied by the
manufacturer of the vent terminal. Properly support
venting. Penetrations through combustible surfaces
must obey all venting clearances dened by local codes
and heater and venting manufacturers. Vent insulation
recommended depending on vent lengths as indicated by
manufacturer. Condensate drains may be recommended as
indicated by manufacturer.
E. Gas Piping: Install gas piping as indicated and in
accordance with NFPA Article 54 National Fuel Gas Code
(latest edition), local requirements and the Installation,
Operation and Service Manual. Gas pressure supply to each
burner shall be as specied by heater manufacturer. For
units running on natural gas, the required gas supply inlet
pressure must be between 5.0 in wc (12.5 mbar) and 14.0
in wc (34.9 mbar). For units running on LPG, the required
gas supply inlet pressure must be between 12.0 in wc (29.9
mbar) and 14.0 in wc (34.9 mbar).
F. Electrical Wiring: Install electrical wiring per NFPA
Article 70 National Electric Code (latest edition), local
requirements and the information and wiring diagrams in
the Installation, Operation and Service Manual.
G. ermostat Devices: Where indicated, provide 24 V
thermostat device connected to heater. Mount thermostat
device 5' - 6' (1.5 m -1.8 m) above nish oor or otherwise
as noted on the drawing. ermostat wiring must follow
local codes. Mount wall instruction tag (provided by
manufacturer) at user level near thermostat device.
H. Start-Up: Start-up, test, and adjust gas-red heaters in
accordance with manufacturer's start-up instructions,
and Utility Company's requirements. Check and calibrate
controls, adjust burners, if applicable, according to
manufacturer's instructions for maximum eciency.
3.2 SCHEDULES
A. See plans.
Installation Code and Annual Inspections:
All installation and service of ROBERTS GORDON® equipment must be performed by a contractor qualified in the installation and
service of equipment sold and supplied by Roberts-Gordon LLC and conform to all requirements set forth in the ROBERTS GORDON®
manuals and all applicable governmental authorities pertaining to the installation, service and operation of the equipment. To help facilitate optimum performance and safety, Roberts-Gordon LLC recommends that a qualified contractor conduct, at a minimum, annual
inspections of your ROBERTS GORDON® equipment and perform service where necessary, using only replacement parts sold and
supplied by Roberts-Gordon LLC.
Further Information: Applications, engineering and detailed guidance on systems design, installation and equipment performance is
available through ROBERTS GORDON® representatives. Please contact us for any further information you may require, including the
Installation, Operation and Service Manual.
These products (with the exception of the UHA[X][S]30 - 75) are not for residential use.
This document is intended to assist licensed professionals in the exercise of their professional judgment.
Roberts-Gordon LLC
1250 William Street
P.O. Box 44
Buffalo, NY 14240-0044 USA
Telephone: +1.716.852.4400
Fax: +1.716.852.0854
Toll Free: 800.828.7450
www.rg-inc.com
© 2009 Roberts-Gordon LLC All rights reserved. No part of this work covered by the copyrights herein may be reproduced or copied in any form or
by any means – graphic, electronic, or mechanical, including photocopying, recording, taping, or information storage
and retrieval systems – without written permission of Roberts-Gordon LLC.
Printed in U.S.A. UHAESNA 1209 Rev A
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