Roberts Gorden Combat UHD-Series Manual

Roberts-Gordon LLC
1250 William Street
P. O . B o x 4 4
Buffalo, New York 14240-0044
Telephone: [phone]
Fax: [phone]
Toll Free: 800.828.7450
www.robertsgordon.com
www.rg-inc.com
Installation, Operation
& Service Manual
Models UHD[T][X][S][R]
150, 175, 200, 225
250, 300, 350, 400
P/N 113001NA 11/13 Rev D
UHD-Series
Tubular Duct Furnace
(Standard Range)
© 2013 Roberts-Gordon LLC
WARNING
FOR YOUR SAFETY
If you smell gas:
1. Open windows.
2. DO NOT try to light any appliance.
3. DO NOT use electrical switches.
4. DO NOT use any telephone in
your building.
5. Extinguish any open flame.
6. Leave the building.
7. Immediately call your local gas
supplier after leaving the building.
Follow the gas supplier’s
instructions.
8. If you cannot reach your gas
supplier, call the Fire Department.
Fire Hazard
Keep all flammable objects, liquids and
vapors the minimum required clear-
ances to combustibles away from
heater.
Some objects will catch fire or explode
when placed close to heater.
Failure to follow these instructions can
result in death, injury or property
damage.
WARNING
Installation must be done by a contractor qualified
in the installation and service of gas-fired heating
equipment or your gas supplier.
Improper installation, adjustment, alteration, service
or maintenance can result in death, injury or
property damage. Read the Installation, Operation
and Service Manual thoroughly before installing or
servicing this equipment.
Installer
Please take the time to read and understand
these instructions prior to any installation.
Installer must give a copy of this manual to the owner.
Owner
Keep this manual in a safe place in order to provide
your service technician with necessary information.
Combat®

P / N 113 0 01 F C 11 / 13 R ev D
AVERTISSEMENT
POUR VOTRE SECURITE
Si vous sentez une odeur de gaz:
1. Ouvrez les fenêtres.
2. N’essayez PAS d’allumer un appareil.
3. N’utilisez PAS d’interrupteurs
électriques.
4. N’utilisez PAS de téléphone dans votre
bâtiment.
5. Eteignez toute flamme nue.
6. Quittez le bâtiment.
7. Après avoir quitté le bâtiment, appelez
immédiatement votre fournisseur local
de gaz.
Suivez les instructions du fournisseur
de gaz.
8. Si vous ne pouvez pas joindre votre
fournisseur de gaz, appelez le service
d’incendie.
Risque d’incendie
Garder tous les objets, liquides ou vapeurs
inflammables à la distance minimale de
l’unité de chauffage requise avec les
matériaux combustibles.
Certains objets prendront feu ou exploseront
s’ils sont placés à proximité de l’unité de
chauffage.
Le non respect de ces instructions peut
entraîner la mort, des blessures corporelles
ou des dommages matériels.
© 2013 Roberts-Gordon LLC
AVERTISSEMENT
L’installation doit être effectuée par un entrepreneur
qualifié dans l'installation et l'entretien d'appareils de
chauffage au gaz ou par votre fournisseur de gaz.
L’installation, le réglage, la modification, la réparation ou
la maintenance inadapté peut entraîner la mort, des
blessures ou des dommages matériels. Lire attentivement
le manuel d'installation, d'utilisation et d'entretien avant
d’installer ou de réparer cet équipement.
Roberts-Gordon LLC
1250 William Street
P. O . B o x 4 4
Buffalo, New York 14240-0044
Téléphone: +1.716.852.4400
Fax: [phone]
Numéro sans fraís: 800.828.7450
www.robertsgordon.com
www.rg-inc.com
Installateur
Veuillez prendre le temps de lire et de comprendre ces
instructions avant toute installation. L’installateur doit
donner un exemplaire de ce manuel au propriétaire.
Propriétaire
Garder ce manuel dans un endroit sûr pour fournir les
informations nécessaires au personnel d’entretien.
Combat®
Manuel d’installation,
d’operation, et de service
Modèles UHD[T][X][S][R]
150, 175, 200, 225
250, 300, 350, 400
UHD-Series Appareil de
chauffage conduit à échangeur
tubulaire (Gamme standard)

© 2013
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 the
written permission of Roberts-Gordon LLC.
Printed in U.S.A.
TABLE OF CONTENTS
SECTION 1: Heater Safety...................................................... 1
1.1 Manpower Requirements ............................................. 1
1.2 Safety Labels and Their Placement ............................. 1
1.3 California Proposition 65 .............................................. 1
SECTION 2: Installer Responsibility ..................................... 5
2.1 Wall Tag ....................................................................... 5
2.2 Corrosive Chemicals.................................................... 5
2.3 National Standards and Applicable Codes .................. 5
SECTION 3: Critical Considerations ..................................... 6
3.1 Basic Information ......................................................... 6
3.2 Manufactured Units...................................................... 6
3.3 Location and Suspension ............................................ 6
3.4 Minimum Required Installation Clearances ................. 6
3.5 Ventilation .................................................................... 6
3.6 Gas Supply .................................................................. 6
3.7 Electrical Supply .......................................................... 6
3.8 Vent.............................................................................. 6
SECTION 4: Clearances to Combustibles............................. 7
4.1 Required Clearances to Combustibles......................... 7
4.2 Clearances to Combustibles ........................................ 7
SECTION 5: National Standards and Applicable Codes ..... 8
5.1 Gas Codes................................................................... 8
5.2 Aircraft Hangars ........................................................... 8
5.3 Parking Structures and Repair Garages ...................... 8
5.4 Electrical ...................................................................... 8
5.5 Venting......................................................................... 8
5.6 High Altitude ................................................................ 9
SECTION 6: Duct Heater Installation................................... 10
6.1 General...................................................................... 10
6.2 Suspension................................................................ 11
SECTION 7: Venting.............................................................. 12
7. 1 Venting ....................................................................... 12
7. 2 Vent Installation .......................................................... 12
7.3 Horizontal Venting ...................................................... 13
7. 4 Vertical Venting........................................................... 13
7.5 Maximum Vent Lengths Table ................................... 13
7. 6 Vent Material............................................................... 13
SECTION 8: Air Supply......................................................... 18
8.1 Separated Combustion Installation ............................ 18
8.2 Building Ventilation .................................................... 18
8.3 Outside Combustion Air Supply................................. 18
SECTION 9: Gas Piping........................................................ 19
9.1 Connections............................................................... 19
SECTION 10: Wiring.............................................................. 21
10.1 Positioning Thermostats .......................................... 21
10.2 LowVoltage Thermostat with One Heater for
Models UHD[T][X][S][R] 150-250 .............................. 21
10.3 LowVoltage Thermostat with One Heater for
Models UHD[X][S][R] 300-400 .................................. 22
10.4 UHD[X][S][R] Series Internal Wiring Diagram for
Single Stage Gas Valves ...........................................23
10.5 UHD[X][S][R] Series Ladder Wiring Diagram for
Single Stage Gas Valves ...........................................24
10.6 UHD[T][X][S][R] Series Internal Wiring Diagram for
Two Stage Gas Valves...............................................25
10.7 UHD[T][X][S][R] Series Ladder Wiring Diagram for
Two Stage Gas Valves...............................................26
10.8 Electrical Connection to the Heater..........................27
SECTION 11: Operation and Maintenance ..........................28
11.1 Pre-Start-Up Checks .................................................28
11.2 Begin Start-Up ..........................................................28
11.3 Pressure Switch ........................................................31
11.4 External Controls ......................................................31
11.5 Complete Start-Up ....................................................31
11.6 Instruction to the User...............................................31
SECTION 12: User Instructions............................................32
12.1 Heater Operation......................................................32
12.2 Lighting Instructions .................................................32
12.3 Simple Troubleshooting ............................................32
SECTION 13: Servicing.........................................................33
13.1 Servicing Instructions...............................................33
13.2 Burner Maintenance.................................................33
13.3 Heat Exchanger Maintenance..................................33
13.4 Gas Valve Maintenance ...........................................34
13.5 Flue Blower ..............................................................34
13.6 Venting and Air Intake Pipe ......................................34
13.7 Maintenance Checklist .............................................34
SECTION 14: Troubleshooting.............................................37
14.1 General ....................................................................38
14.2 Troubleshooting For Automatic Ignition Burner
Systems...................................................................39
14.3 Troubleshooting for Flame Supervision System .......40
14.4 Troubleshooting for Gas Valves................................41
14.5 Troubleshooting for Flue Blower...............................41
SECTION 15: Replacement Parts.........................................42
15.1 Gas Valve .................................................................42
15.2 Burner Compartment for Models UHA[T][X][S][R]
150-250......................................................................43
15.3 Burner Compartment for Models UHD[X][S][R]
300-400 .....................................................................45
15.4 Ignition Electrode and Flame Probe for Models
UHD[T][X][S][R] 150-250 ...........................................46
15.5 Ignition Electrode and Flame Probe for Models
UHD[X][S][R] 300-400 ...............................................47
15.6 Heat Exchanger .......................................................48
15.7 Flue Blower for Models UHD[T][X][S][R] 150-175 ....48
15.8 Flue Blower for Models UHD[T][X][S][R] 200-250 ...49
15.9 Flue Blower for Models UHD[X][S][R] 300-400 ........50

15.10 Pressure Switch ..................................................... 51
15.11 Ignition Control....................................................... 51
15.12 Limit Switches........................................................ 51
SECTION 16: Specifications ................................................ 52
16.1 Dimension Data for Models UHD[T][X][S][R]
150-250.................................................................... 52
16.2 General Technical Data Table.................................. 53
16.3 Technical Data Table................................................ 53
16.4 Dimension Data for Models UHD[X][S][R]300-400 .. 54
16.5 General Technical Data Table.................................. 55
16.6 Technical Data Table................................................ 55
SECTION 17: The ROBERTS GORDON®UHD-Series
Warranty ......................................................... 57

TABLE OF FIGURES
Figure 1: UHD[T][X][S][R] 150-175 Label Placement................ 2
Figure 2: UHD[T][X][S][R] 200-250 Label Placement ............... 3
Figure 3: UHD[X][S][R] 300 – 400 Label Placement ................. 4
Figure 4: Clearances to Combustibles ...................................... 7
Figure 5: Air FlowDirection..................................................... 10
Figure 6: Suspension Methods ............................................... 11
Figure 7: Vent and Roof Detail ................................................ 13
Figure 8: Standard Vented Heater - Vertical and Horizontal
Vent Termination...................................................... 14
Figure 9: Standard Vented Heater - Common Vertical Vent
Termination.............................................................. 15
Figure 10: Separated Combustion Heater - Vertical and
Horizontal Vent Termination..................................... 16
Figure 11: Concentric Vent Box ............................................... 16
Figure 12: Concentric Vertical and Horizontal Vent
Termination - Separated Combustion Heater .......... 17
Figure 13: Gas Connection ..................................................... 20
Figure 14: Automatic Burner Control Sequence...................... 29
Figure 15: Single Stage Gas Valve for Models UHD[X][S][R]
150 – 400................................................................. 29
Figure 16: Two Stage Gas Valve for Models UHD[T][X][S][R]
150 - 250 ................................................................. 30
Figure 17: LED Diagnostic Codes........................................... 32
There are references in this manual to various trademarks. All trademarks mentioned herein, whether registered or not, are the
property of their respective owners. Roberts-Gordon LLC is not sponsored by or affiliated with any of the trademark or registered
trademark owners, and makes no representations about them, their owners, their products or services.

SECTION 1: HEATER SAFETY
1 of 57
SECTION 1: HEATER SAFETY
Yo ur Safety is Important to Us!
This symbol is used throughout
the manual to notify youof
possible fire, electrical or burn
hazards. Please pay special
attention when reading and
following the warnings in these
sections.
Installation, service and, at a
minimum, annual inspection of heater must be done
by a contractor qualified in the installation and
service of gas-fired heating equipment.
Read this manual carefully before installation,
operation or service of this equipment.
Heaters are not approved for residential installation.
These instructions, the layout drawing, local codes
and ordinances and applicable standards that apply
to gas piping, electrical wiring, venting, etc. must be
thoroughly understood before proceeding with the
installation.
Protective gear is to be worn during installation,
operation and service. Thin sheet metal parts,
including the various venting components, have
sharp edges. To prevent injury, the use of work
gloves is recommended.
Before installation, check that the local distribution
conditions, nature of gas and pressure and
adjustment of the appliance are compatible.
This heater must be applied and operated under the
general concepts of reasonable use and installed
using the best building practices.
This appliance is not intended for use by persons
(including children) with reduced physical, sensory
or mental capabilities, or lack of experience and
knowledge, unless they have been given
supervision or instruction concerning use of the
appliance by a person responsible for their safety.
Children should be supervised to ensure that they
do not play with the appliance.
For additional copies of the Installation, Operation
and Service Manual, please contact Roberts-
Gordon LLC.
1. 1 M a n p o we r R e quirements
To prevent personal injury and damage to the
heater, two persons will be required for installation.
1.2 Safety Labels and Their Placement
Product safety signs or labels should be replaced by
the product user when they are no longer legible.
Please contact Roberts-Gordon LLC or your
ROBERTS GORDON®independent distributor to
obtain replacement signs or labels. See Page 2,
Figure 1 through Page 4, Figure 3.
1.3 California Proposition 65
In accordance with California Proposition 65
requirements, a warning label must be placed in a
highly visible location on the outside of the
equipment (i.e. near equipment's serial plate). See
label placement drawing on Page 2, Figure 1
through Page 4, Figure 3 for label location. Avoid
placing label on areas with extreme heat, cold,
corrosive chemicals or other elements. To order
additional labels, please contact Roberts-Gordon
LLC or your ROBERTS GORDON®independent
distributor.

UHD STANDARD DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
2 of 57
Figure 1: UHD[T][X][S][R] 150-175 Label Placement
Description Part Number
Logo Label 91040030
Vent Length Label 91039505
Vent to Outdoors Label 91010427
Warning Label 91010429
Rating Plate Label 91039802
Installation Label 91010431
Instruction Location Label 91010433
Lighting Instruction Label 91010425
Venting Arrangement Label* 91010426
Proposition 65 Label 91070015
* For separated combustion units only

SECTION 1: HEATER SAFETY
3 of 57
Figure 2: UHD[T][X][S][R] 200-250 Label Placement
Description Part Number
Logo Label 91040030
Vent Length Label 91039505
Vent to Outdoors Label 91010427
Warning Label 91010429
Rating Plate Label 91039802
Installation Label 91010431
Instruction Location Label 91010433
Lighting Instruction Label 91010425
Venting Arrangement Label* 91010426
Proposition 65 Label 91070015
* For separated combustion units only

UHD STANDARD DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
4 of 57
Figure 3: UHD[X][S][R] 300 – 400 Label Placement
VENT TO OUTDOORS
DONNER VENT
A DEHORS
© 2006 Roberts-Gordon, LLC P/N 91010427
Printed in U.S.A. / Imprimé aux Etats Unis
* For separated combustion units only
Description Part Number
Logo Label 91040030
Vent Length Label 91039505
Vent to Outdoors Label 91010427
Warning Label 91010429
Rating Plate Label 91039802
Installation Label 91010431
Instruction Location Label 91010433
Lighting Instruction Label 91010425
Venting Arrangement Label* 91010426
Proposition 65 Label 91070015

SECTION 2: INSTALLER RESPONSIBILITY
5 of 57
SECTION 2: INSTALLER RESPONSIBILITY
The installer is responsible for the following:
• To install the heater, as well as the gas and
electrical supplies, in accordance with applicable
specifications and codes. Roberts-Gordon LLC
recommends the installer contact a Local
Building Inspector or Fire Marshal for guidance.
• To use the information given in a layout drawing
and in the manual together with the cited codes
and regulations to perform the installation.
• To install the heater in accordance with the
clearances to combustibles.
• To furnish all needed materials not supplied as
standard equipment.
• To plan location of supports, vents and air
intakes.
• To provide access for servicing.
• To provide the owner with a copy of this
Installation, Operation and Service Manual.
• To never use heater as support for a ladder or
other access equipment and never hang or
suspend anything from heater.
• To ensure there is adequate air circulation
around the heater and to supply air for
combustion, ventilation and distribution in
accordance with local codes.
• To provide a method that ensures that the air flow
through the heat exchanger is within the
acceptable range indicated on the serial plate
prior to energizing the heater, and that such air
flowcontinues at least 90 seconds after the
heater is de-energized.
• To ensure the heater is placed in an approved
application.
2.1 Wall Tag
A laminated wall tag is included with the heater as a
permanent reminder of the safety instructions and
the importance of the required clearances to
combustibles. Affix the tag by peeling off the backing
of the adhesive strips on the rear surface and
position the tag on a wall near the heater.
A copy of the wall tag (P/N 91039831) is illustrated
on the back cover.
Knowyour model number and installed
configuration. Model number and installed
configuration are found on the heater serial plate
and throughout the Installation, Operation and
Service Manual.
2.2 Corrosive Chemicals
Roberts-Gordon LLC cannot be responsible for
ensuring that all appropriate safety measures are
undertaken prior to installation; this is entirely the
responsibility of the installer. It is essential that the
contractor, the sub-contractor, or the owner
identifies the presence of combustible materials,
corrosive chemicals or halogenated hydrocarbons*
anywhere in the premises.
* HalogenatedHydrocarbons are a family of chemical
compounds characterized by the presence of halogen ele-
ments (fluorine, chlorine, bromine, etc.). These compounds are
frequently used in refrigerants, cleaning agents, solvents, etc. If
these compounds enter the air supply of the burner, the life
span of the heater components will be greatly reduced. An out-
side air supply must be provided to the burners whenever the
presence of these compounds is suspected. Warranty will be
invalid if the heater is exposed to halogenated hydrocarbons.
2.3 National Standards and Applicable Codes
All appliances must be installed in accordance with
the latest revision of the applicable standards and
national codes. This refers also to the electric, gas
and venting installation. Note: Additional standards
for installations in public garages, aircraft hangars,
etc. may be applicable. See Page 8, Section 5.
CAUTION
Product Damage Hazard
Do not use equipment in area containing
corrosive chemicals.
Refer to appropriate Material Safety Data
Sheets (MSDS).
Failure to follow these instructions can result
in product damage.

UHD STANDARD DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
6 of 57
SECTION 3: CRITICAL CONSIDERATIONS
3.1 Basic Information
UHD[T][X][S][R] heaters have automatic ignition
burners for ON/OFF or HIGH/LOW operation only.
3.2 Manufactured Units
Gas-fired, power-vented duct furnace with tubular
heat exchanger. Units shall have a minimum of 82%
thermal efficiency. The standard unit shall consist of
a non-separated combustion design with an
aluminized heat exchanger and a single stage gas
valve. Design and heat exchanger alternatives shall
be offered as follows:
• Separated Combustion: [S] For Models 150-250,
a separated combustion unit shall consist of a
sealed hinged enclosure.
Combustion air inlet flange on rear of heater
allows for combustion air from outside heated
space to be attached.
For Models 300-400, a separated combustion
unit shall feature an enclosed, sealed burner
box. A piece of flexible air duct connects this
burner box to a flange on the cabinet.
Combustion air shall be ducted from outside the
heated space, with the ductwork connecting to
the unit with the use of the flange.
• Stainless Steel Heat Exchanger: [X] A stainless
steel heat exchanger unit shall consist of heat
exchanger tubes, heat exchanger tube supports
and heat exchanger tube plate produced of 409
stainless steel.
Air inlet temperatures below40° F (4.4° C) are
not recommended.
•Two Stage Gas Valve: [T] A two stage gas valve
shall allowheater to function in HIGH/LOW
operation.
• Approved for Installation Downstream of a
Refrigeration System: [R] Installation allows for
unit to be installed downstream of a refrigeration
system. Unit design shall include a 409 stainless
steel package. Stainless steel package includes
heat exchanger, tube supports and drip pan.
3.3 Location and Suspension
All models:
•Must be installed indoors.
•Must be installed on the positive pressure side of
the air circulation blower.
•Must be installed in a level position with
horizontal discharge.
• May be mounted on a shelf of non-combustible
material.
• May be suspended from above (See Page 11,
Section 6.2) or from wall brackets of sufficient
strength to support the heater as listed in the
Technical Data Table on Page 53, Section 16.2
and Page 55, Section 16.5.
• Drop rods must be a minimum of 3/8" diameter
mild steel. Four suspension points (3/8" nuts)
are located on top of the heater.
•Must be installed in a manner which allows
access to all serviceable components.
3.4 Minimum Required Installation Clearances
Clearances around the heater and vent must be as
indicated on Page 7, Figure 4 and Page 12, Section
7to ensure access for servicing and correct
operation.
3.5 Ventilation
It is important to ensure that there is adequate air
space around the heater to supply air for
combustion, ventilation and distribution in
accordance with local and national code on Page
12, Section 7.
3.6 Gas Supply
It is important that the gas supply pipe is sized
correctly to provide the inlet pressure as stated on
the heater data plate. The gas supply pipe and
electrical connections must not support any of the
heater's weight. See Page 19, Section 9.
3.7 Electrical Supply
A permanent 120 V/ 1 Ø / 60 Hz electrical supply is
required for the main electrical power. The heater
also requires suitable controls listed on Page 21,
Section 10.
3.8Vent
Choose heater orientation to allowfor proper
location of the vent. Each heater must be fitted with
a correctly sized sealed vent system.
If vented horizontally, no other appliance may be
connected to the vent. See Page 12, Section 7.

SECTION 4: CLEARANCES TO COMBUSTIBLES
7 of 57
SECTION 4: CLEARANCES TO COMBUSTIBLES
4.1 Required Clearances to Combustibles
Clearances are the required distances that
combustible objects must be away from the heater
to prevent a fire hazard. Combustibles are materials
that may catch on fire and include common items
such as wood, paper, rubber, fabric, etc. Maintain
clearances to combustibles at all times for safety.
Clearances for all heater models are located on the
serial plate, wall tag and throughout the manual.
Check the clearances on the serial plate to make
sure the product is suitable for your application and
the clearances are maintained. Read and followthe
safety guidelines below:
• Keep gasoline or other combustible material
including flammable objects, liquids, dust or
vapors away from this heater or any other
appliance.
• Do not spray aerosols in the vicinity of this
heater.
• The stated clearances to combustibles
represents a surface temperature of 90° F
(50° C) above room temperature. Building
materials with a lowheat tolerance (such as
plastics, vinyl siding, canvas, tri-ply, etc.) may be
subject to degradation at lower temperatures. It
is the installer's and owner's responsibility to
assure that adjacent materials are protected
from degradation.
• Maintain clearances from heat sensitive
equipment and work stations.
• Consult local Fire Marshal, Fire Insurance
Carrier or other authorities for approval of
proposed installation when there is a possibility
of exposure to combustible airborne materials or
vapors.
4.2 Clearances to Combustibles
Clearances must be as indicated on Page 7, Figure
4. If clearances to combustibles are not indicated,
then installation clearances apply.
All distances are minimum clearance requirements
for service access, air flowand safety.
Figure 4: Clearances to Combustibles
WARNING
Fire Hazard
Keep all flammable objects, liquids and
vapors the required clearances to
combustibles away from heater.
Some objects can catch fire or explode
when placed close to heater.
Failure to follow these instructions can
result in death, injury or property damage.
6"
(15 cm)
6"
(15 cm)
31"*
(79 cm)
6"
(15 cm)
Clearance to Vent: 2" (5 cm)
*31" (79 cm) minimum is necessary
for servicing.

UHD STANDARD DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
8 of 57
SECTION 5: NATIONAL STANDARDS AND APPLICABLE CODES
5.1 Gas Codes
The type of gas appearing on the serial plate
must be the type of gas used. Installation must
comply with national and local codes and
requirements of the local gas company.
United States: Refer to NFPA 54/ANSI Z223.1 -
latest revision, National Fuel Gas Code.
Canada: Refer to CSA B149.1 Natural Gas and
Propane Installation Code.
5.2 Aircraft Hangars
Installation in aircraft hangars must be in
accordance with the following codes:
United States: Refer to Standard for Aircraft
Hangars, NFPA 409 - latest revision.
Canada: Refer to Standard CSA B149.1
Natural Gas and Propane Installation Code.
• In aircraft storage and servicing areas,
heaters shall be installed at least 10' (3 m)
above the upper surface of wings or of engine
enclosures of the highest aircraft which may be
housed in the hangar. The measurement shall
be made from the wing or engine enclosure
(whichever is higher from the floor) to the
bottom of the heater.
• In shops, offices and other sections of aircraft
hangars communicating with aircraft storage or
servicing areas, heaters shall be installed not
less than 8' (2.4 m) above the floor.
• Suspended or elevated heaters shall be so
located in all spaces of aircraft hangars that
they shall not be subject to injury by aircraft,
cranes, movable scaffolding or other objects.
Provisions shall be made to assure
accessibility to suspended heaters for recurrent
maintenance purposes.
5.3 ParkingStructures and Repair Garages
Installation in garages must be in accordance
with the following codes:
United States: Standard for Parking Structures
NFPA 88A - latest revision or the Code for
Motor Fuel Dispensing Facilities and Repair
Garages, NFPA 30A - latest revision. Canada:
Refer to CSA B149.1 Natural Gas and Propane
Installation Code.
• In accordance with the Standard for Parking
Structures NFPA 88A, heaters must be located
a minimum of 18" (50 cm) belowthe floor-
ceiling assembly or 18" (50 cm) above the floor.
• In accordance with the Code for Motor Fuel
Dispensing Facilities and Repair Garages,
NFPA 30A - latest revision, heaters must not be
installed less than 8' (2.4 m) above the floor.
5.4 Electrical
The heater must be electrically grounded in
accordance with the following codes:
United States: Refer to National Electrical
Code®, NFPA 70 - latest revision. Wiring must
conform to the most current National Electrical
Code®, local ordinances and any special
diagrams furnished.
Canada: Refer to Canadian Electrical Code,
CSA C22.1 Part 1 - latest revision.
5.5 Venting
The venting must be installed in accordance
with the requirements within this manual and
the following codes:
United States: Refer to NFPA 54/ANSI Z223.1 -
latest revision, National Fuel Gas Code.
Canada: Refer to CSA B149.1 Natural Gas and
Propane Installation Code.

SECTION 5: NATIONAL STANDARDS AND APPLICABLE CODES
9 of 57
5.6 High Altitude
These heaters are approved (without
modifications) for installations up to 2000' (610
m) in US and Canada. Heaters installed above
2000' (610 m) must be de-rated. For
installations above 2000' (610 m) in US, consult
factory for information on burner de-rating. For
installations from 2000' (610 m) to 4500'
(1370m) in Canada, high altitude conversion
kits are available. Heaters installed over 4500'
(1370 m) in Canada are not approved and must
be approved by the local or provincial authority.

UHD STANDARD DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
10 of 57
SECTION 6: DUCT HEATER INSTALLATION
6.1 General
To connect the inlet and outlet ducts to the heater,
Duct-Mate or similar flanges may be slid over the
duct connector flanges supplied on the unit and
secured with screws. The connection to the duct
then can be made using the Duct-Mate clips. The
ducts must have removable access panels
upstream and downstream of the heater. These
panels must be of appropriate size and placement
so that smoke or reflected light could be observed to
indicate the presence of leaks in the heat
exchanger. Covers for these openings should be
sealed to prevent leakage.
Any transition into the inlet of the heater should be
smooth, with a taper of no more than 15 degrees. If
elbows are required, they should be of either broad
radius or fitted with properly designed turning vanes.
Consult a professional to ensure turning vanes are
properly designed.
The heater must be installed on the positive
pressure side of the circulating air blower. Air flow
through the heater must be as shown on Page 10,
Figure 5 and may not be reversed. The air flowmust
be adjusted such that it is within the acceptable
range shown on Page 10, Section 6.1.2.
The minimum inlet duct lengths shown on Page 10,
Section 6.1.1 must be observed. Pressure drop
through the heat exchanger at various air flows is
shown on Page 10, Section 6.1.2.
Figure 5: Air Flow Direction
6.1.1 Minimum Inlet Duct Length
6.1.2 Temperature Rise and Pressure Drop Ranges
Model Duct Length Duct Size (W X H)
UHD[T][X][S][R] 150-175 52" (132 cm) 28" x 24" (71 cm x 60 cm)
UHD[T][X][S][R] 200-250 60" (162 cm) 28" x 32 1/2" (71 cm x 83 cm)
UHD[X][S][R] 300-400 75" (190 cm) 35" x 40 1/2" (89 cm x 82 cm)
UHD[T][X][S][R] 150 UHD[T][X][S][R] 175 UHD[T][X][S][R] 200 UHD[T][X][S][R] 225
Airflow
(CFM)
Temperature
Rise (°F)
Pressure
Drop
(in wc)
Airflow
(CFM)
Temperature
Rise (°F)
Pressure
Drop
(in wc)
Airflow
(CFM)
Temperature
Rise (°F)
Pressure
Drop
(in wc)
Airflow
(CFM)
Temperature
Rise (°F)
Pressure
Drop
(in wc)
1,360 83 0.02 1,400 95 0.03 2,050 73 0.025 2,100 80 0.035
1,950 58 0.035 2,180 62 0.06 2,600 58 0.035 2,800 61 0.052
2,800 41 0.057 3,244 42 0.10 3,600 42 0.056 4,600 37 0.110
3,700 31 0.083 4,370 31 0.15 5,500 28 0.100 6,230 27 0.167
4,700 24 0.12 5,160 27 0.19 6,570 23.5 0.129 7,400 23 0.214
5,800 20 0.16 6,850 20 0.29 7,750 20 0.163 8,300 20 0.253
UHD[T][X][S][R] 250 UHD[X][S][R] 300 UHD[X][S][R] 350 UHD[X][S][R] 400
Airflow
(CFM)
Temperature
Rise (°F)
Pressure
Drop
(in wc)
Airflow
(CFM)
Temperature
Rise (°F)
Pressure
Drop
(in wc)
Airflow
(CFM)
Temperature
Rise (°F)
Pressure
Drop
(in wc)
Airflow
(CFM)
Temperature
Rise (°F)
Pressure
Drop
(in wc)
2,350 80 0.05 2,700 86 0.02 3,120 86 0.03 3,420 86 0.04
3,000 63 0.07 4,735 50 0.06 4,880 56 0.07 5,200 57 0.08
4,400 43 0.13 6,813 35 0.12 6,612 41 0.123 6,700 45 0.13
5,900 32 0.19 8,000 30 0.17 9,140 30 0.23 8,850 34 0.21
7,625 25 0.28 9,300 26 0.22 10,500 26 0.30 11,600 26 0.36
8,850 22 0.35 10,200 23 0.27 13,600 22 0.48 14,200 22 0.53

SECTION 6: DUCT HEATER INSTALLATION
11 of 57
6.2 Suspension
For typical suspension, See Page 11, Figure 6.
When handling or supporting the heater from below,
ensure that the weight is taken at the support points.
The gas or electrical supply lines must not be used
to support the heater.
Do not locate the gas or electrical supply lines
directly over the path of the flue products from the
heater.
The heater must be installed in a location that is
readily accessible for servicing.
The heater must be installed in accordance with
clearances to combustibles as indicated on the
serial plate, wall tag and throughout the manual.
See Page 7, Section 4.
Figure 6: Suspension Methods
WARNING
Crush Hazard
Use 3/8" threaded rod
minimum.
Failure to follow these
instructions can result in
death, injury or property
damage.
Nut
Washer
Riv
Nut
Ensure all 3/8"-16 threaded
suspension hardware is
torqued to a minimum of
19 ft lbs. (25.8Nm)
Support Points (for use in handling)
3/8"-16
Threaded
Rod
Cone Point
Set Pin
Window
Clamp
Unistrut
Unistrut
3/8"-16
Threaded
Rod
Washer
Nut
Channel Nut
NOTE:
Four suspension
points located on top
of heater. Duct
supports not shown.
Duct supports and
duct are not provided
by manufacturer.

UHD STANDARD DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
12 of 57
SECTION 7: VENTING
7. 1 V e n t i n g
This heater must be vented in accordance with the
rules contained in this manual and with the following
national codes and any state, provincial or local
codes which may apply: United States: Refer to
NFPA 54/ANSI Z223.1 - latest revision, National
Fuel Gas Code; Canada: Refer to CSA B149.1
Natural Gas and Propane Installation Code.
Any portion of vent pipe passing through a
combustible wall must have a listed thimble to
conform with the above codes.
The bottom of the vent or air intake terminal shall not
be located less than 1' (.3 m) above grade level.
The vent shall not terminate less than 7' (2.1 m)
above grade where located adjacent to public
walkways.
Vent terminal must be installed at a height sufficient
to prevent blockage by snowand building materials
protected from degradation by flue gasses.
Vent terminal must be beyond any combustible
overhang.
Secure all joints with corrosion resistant #8 x 3/8"
sheet metal screws.
For single wall venting, pressure sensitive aluminum
tape or silicone sealant must be used to seal all
joints.
Aluminum tape shall have a minimum temperature
rating of 400° F (204° C) and meet SMACNA AFTS-
100-73 standards. High temperature silicone sealant
must have a minimum temperature rating of 480° F
(250° C).
7.1.1 United States Requirements
Vent must terminate at least 3' (.9 m) above any
forced air inlet located within 10' (3.1 m).
Vent must terminate at least 4' (1.2 m) below,
4' (1.2 m) horizontally from, or 1' (.3 m) above any
door, operable window, or gravity air inlet into any
building.
NFPA 54/ANSI Z223.1 - latest revision, National
Fuel Gas Code specifies a 4' (1.2 m) horizontal vent
terminal clearance from gas and electric meters,
regulators and relief equipment.
7. 1. 2 C a n a d i a n R e quirements
The vent shall not terminate within 6' (1.8 m) of a
mechanical air supply inlet to any building.
The vent shall not terminate within 3' (.9 m) of a
windowor door that can be opened in any building,
any non-mechanical air supply inlet to any building,
or of the combustion air inlet of any other appliance.
7.2 Vent Installation
Maintain clearances to combustibles at all times for
safety. Clearances are the required distances that
combustible objects must be away from the heater
to prevent serious fire hazard. See Page 7
, Section
4. For vented units, the vent must terminate outside
of the building.
Vents must be fully sealed and correctly sized for
the model. If the vent passes through a wall or
ceiling of combustible material, it must be enclosed
by a listed thimble and be separated from the
thimble by at least a 2" (5 cm) air gap.
For separated combustion models, vents and air
intakes must be a fully sealed system and correctly
sized for the model. Vent should be assembled as
detailed on Page 13, Figure 7 through Page 17,
Figure 12.
The joints between the vent terminal and the roof or
wall must be properly sealed.
Vents and air intakes must be adequately
supported so that the heater does not bear the
weight of the pipes.
For vent termination See Page 13, Figure 7 through
Page 17, Figure 12.
7.2.1 Standard Vented Heaters
(Models UHD[T][X][R] 150 - 250 and Models
UHD[X][R] 300 - 400)
The vent must be fitted with a lowresistance
terminal. See Page 13, Figure 7 through Page 15,
Figure 9. Standard vented heaters do not allow
outdoor air intake for combustion air.
7.2.2 Separated Combustion Heaters
(Models UHD[T][X]S[R] 150 - 250 and Models
UHD[X]S[R] 300 - 400)
The heaters are designed to be installed as
separated combustion heaters. The vent and air
intake are run as separate pipes to the wall or roof
WARNING
Carbon Monoxide Hazard
Heaters must be vented
outdoors.
Heaters must be installed
according to the
installation manual.
Failure to follow these
instructions can result in
death or injury.