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.
WARNING
Fire Hazard
UHD-Series
Tubular Duct Furnace
(Low Profile Range)
Installation, Operation
& Service Manual
Models UHD[X][S]
75, 100, 125
Keep all flammable objects, liquids and
vapors the minimum required clearances 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
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.
Installation must be done by a contractor qualified
in the installation and service of gas-fired heating
equipment or your gas supplier.
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.
Rapid Engineering LLC
1100 Seven Mile Road NW
Comstock Park, MI 49321
Telephone: +1.616.784.0500
Fax: +1.616.784.1910
Toll Free: 800.536.3461
4. N’utiliser pas de téléphone dans votre
bâtiment.
5. Eteindre flamme nue.
6. Quitter le bâtiment.
7. Après avoir quitté le bâtiment, appelez
immédiatement votre fournisseur local
de gaz.
Suivre les instructions du fournisseur
de gaz.
8. Si vous ne pouvez pas joindre votre
fournisseur de gaz, appeler le service
d’incendie.
UHD-Series
Appareil de chauffage conduit à
échangeur tubulaire
(Gamme compacte)
AVERTISSEMENT
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.
Manuel d’installation,
d’operation, et de service
Modèles UHD[X][S]
75, 100, 125
AVERTISSEMENT
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.
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.
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 Rapid Engineering LLC.
Figure 18: LED Diagnostic Codes ...........................................29
There are references in this manual to various trademarks. All trademarks mentioned herein, whether registered or not, are the
property of their respective owners. Rapid Engineering 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.
Page 8
Page 9
SECTION 1: HEATER SAFETY
Your Safety is Important to Us!
This symbol is used throughout
the manual to notify you of
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
installations. 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.
SECTION 1: HEATER SAFETY
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 Rapid Engineering LLC or your
RAPID
®
independent distributor to obtain
replacement signs or labels. See Page 2, Figure 1 through Page 3, Figure 2.
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 3, Figure 2 for label location. Avoid
placing label on areas with extreme heat, cold,
corrosive chemicals or other elements. To order
additional labels, please contact Rapid Engineering
LLC or your RAPID
®
independent distributor.
Protective gear is to be worn during installation,
operation and service in accordance to the
Occupational Safety and Health Administration
(OSHA). Gear must be in accordance to NFPA 70E,
latest revision when working with electrical
components. Thin sheet metal parts 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 equipment are compatible.
This heater must be applied and operated under the
general concepts of reasonable use and installed
using the best building practices.
This equipment 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
equipment by a person responsible for their safety.
Children should be supervised to ensure that they
do not play with the equipment.
For additional copies of the Installation, Operation
and Service Manual, please contact Rapid
Engineering LLC.
1.1 Manpower Requirements
To prevent personal injury and damage to the
heater, two persons will be required for installation.
1 of 45
Page 10
UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
SECTION 2: INSTALLER RESPONSIBILITY
The installer is responsible for the following:
2.2 Corrosive Chemicals
• To install the heater, as well as the gas and
electrical supplies, in accordance with applicable
specifications and codes. Rapid Engineering
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.
Do not use heater in area containing
corrosive chemicals.
Refer to appropriate Material Safety Data
Sheets (MSDS).
CAUTION
Product Damage Hazard
• 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
flow continues 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 91039833) is illustrated
on the back cover.
Know your 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.
Failure to follow these instructions can result
in product damage.
Rapid Engineering 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.
* Halogenated Hydrocarbons are a family of chemical
compounds characterized by the presence of halogen
elements (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 outside 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 equipment 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 7, Section 5.
4 of 45
Page 13
SECTION 3: CRITICAL CONSIDERATIONS
3.1 Basic Information
UHD[X][S] heaters have automatic ignition burners
for ON/OFF 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 single stage gas
valve. Design and heat exchanger alternatives shall
be offered as follows:
• Separated Combustion: [S] A separated
combustion unit shall consist of a sealed
enclosure with a hinged door. Combustion air
inlet on rear of heater allows for intake venting
from outside of heated space to be attached.
Combustion flue gasses shall be ducted from
outside the heated space by ductwork
connected to unit’s outlet 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 plates produced of 409
stainless steel. Air inlet temperatures below 40
°F (4.4 °C) are not recommended for this
application.
SECTION 3: CRITICAL CONSIDERATIONS
• 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 6, Figure 3 and Page 11, Section 7 to 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 codes. See Page 11, 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 serial 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.
3.3 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 using shelf mounting brackets. See Page 10, Figure 6and Page 10, Figure 7 for
details.
• May be suspended from above (See Page 9, Section 6.2) or from wall brackets of sufficient
strength to support the heater as listed in the
Technical Data Table on Page 44, Section 16.2.
• 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.
3.8 Vent
Choose heater orientation to allow for proper
location of the vent. Each heater must be fitted with
a correctly sized sealed vent system.
If vented horizontally, no other equipment may be
connected to the vent. See Page 11, Section 7.
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Page 14
UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
SECTION 4: CLEARANCES TO COMBUSTIBLES
4.1 Required Clearances to Combustibles
WARNING
Fire Hazard
Keep all flammable objects, liquids and
vapors the minimum required clearances 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.
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 follow the
safety guidelines below:
• Keep gasoline or other combustible material
including flammable objects, liquids, dust or
vapors away from this heater or any other
equipment.
• 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 low heat 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 6, Figure
3. If clearances to combustibles are not indicated,
then installation clearances apply.
All distances are minimum clearance requirements
for service access, air flow and safety.
Figure 3: Clearances to Combustibles
Clearance to Vent: 2" (5 cm)
*23" (58.4 cm) minimum is necessary for
servicing.
6 of 45
Page 15
SECTION 5: NATIONAL STANDARDS AND APPLICABLE CODES
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 Natural Gas and Propane
Installation Code, Standard CSA B149.1 - latest
revision.
5.3 Parking Structures and Repair Garages
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.
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.
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 Natural Gas and Propane
Installation Code, Standard CSA B149.1 - latest
revision.
5.4 Electrical
The heater must be electrically grounded in
accordance with the following codes:
United States: Refer to National Electrical
®
, NFPA 70 - latest revision. Wiring must
Code
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.
7 of 45
Page 16
UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
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 8, Figure 4 and may not be reversed. The air flow must
be adjusted such that it is within the acceptable
range shown on Page 8, Section 6.1.2. The
minimum inlet duct lengths shown on Page 8, Section 6.1.1 should be observed. Pressure drop
through the heat exchanger at various air flows is
given on Page 8, Section 6.1.2.
Figure 4: Air Flow Direction
OUTLET DUCT
AIR FLOW
INLET DUCT
6.1.1 Minimum Inlet Duct Length
ModelDuct LengthDuct Size (H x W)
UHD[X][S] 75 32" (81 cm)16 3/4" x 15 7/8" (43 cm x 40 cm)
UHD[X][S] 100 &12537" (94 cm)21 3/4" x 15 7/8" (55 cm x 40 cm)
Failure to follow these
instructions can result in
death, injury or property
damage.
When handling or supporting the heater from below,
ensure that the weight is taken at the support points.
For typical suspension, See Page 9, Figure 5.
For typical shelf mounting on existing shelf, See Page 10, Figure 6.
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.
Figure 5: Suspension Methods
SECTION 6: DUCT HEATER INSTALLATION
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 6, Section 4.
6.3 Wall Mounting
For typical suspension, See Page 10, Figure 7. Wall
mounted heaters blowing parallel to the wall can
only be installed with the service door away from the
wall.
The wall mounting brackets must be attached to a
suitable wall using all mounting holes. Screw sizes
less than 3/8" may not be used. In order for the wall
mounting brackets to adequately carry the weight of
the heater, it must be installed according to best
building practices.
9 of 45
Page 18
UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
Wall Mounting Bracket Arm Left111WALL1L1
Wall Mounting Bracket Arm Right111WALL1R1
Wall Mounting Bracket Vertical111WALL22
Wall Mounting Bracket Diagonal111WALL32
5/16" x 3 1/2" Bolt972139256
5/16" Lock Nut with Nylon Insert921140006
5/16" Flat Washer952116006
5/16" Lockwasher964116006
10 of 45
Page 19
SECTION 7: VENTING
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.
SECTION 7: VENTING
7.2.1 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 Changing Vent and Air Intake Orientation
The heater is sold with rear horizontal vent and air
intake connections as standard. (only separated
combustion models have air intake connection). If
vertical vent and air intake connections are required,
follow the instructions on Page 41, Section 15.5.
7.2 Venting
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 snow and 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 AFTS100-73 standards. High temperature silicone sealant
must have a minimum temperature rating of 480° F
(250° C).
7.2.2 Canadian Requirements
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
window or 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 piece of
equipment.
7.3 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 6, Figure 3.
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 8 through Page 17, Figure 13. 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 8 through
Page 17, Figure 13.
11 of 45
Page 20
UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
7.3.1 Standard Vented Heaters
(Models UHD[X] 75 - 125)
The vent must be fitted with a low resistance
terminal. See Page 13, Figure 8 through Page 15, Figure 10. Standard vented heaters do not allow
outdoor air intake for combustion air.
separated combustion heaters. The vent and air
intake are run as separate pipes to the wall or roof
terminals. See Page 16, Figure 11. As an option, the
vent and air intake are run as separate pipes to a
concentric vent box and a concentric vent/air intake
pipe penetrates the wall or roof. See Page 16, Figure 12and Page 17, Figure 13.
For separated combustion installation, the vent and
air intake must be fitted with an individual and
correctly sized sealed system and the vent and air
intake must terminate at approved wall and roof
terminals.
Separated combustion units may not be common
vented.
7.4 Horizontal Venting
Horizontally vented heaters must be individually
vented, no common venting.
Vent pipe must be sloped ¼" (.6 cm) downward for
every 1' (.3 m). For vent lengths greater than 10'
(3 m), condensation will form. Insulation is
recommended and condensation drains may be
desired. For vents pitched up towards the vent
terminal, place the condensation drain within 10'
(3.0 m) of the heater.
In noncombustible walls only, vent terminal
(P/N 02537801-1P) may be used.
For 4'' (10 cm) vents in either combustible or
noncombustible walls, use vent terminal (P/N
90502100) or equivalent insulated vent terminal.
Follow the manufacturer's instructions for proper
installation.
Instead of an insulated vent terminal, a listed thimble
with 2" (5 cm) air gap may be used with a 4" (10 cm)
vent cap (P/N 90502102).
7.5 Vertical Venting
Vertically vented standard-vented heaters can be
common vented (up to four heaters).
For vent lengths greater than 10' (3.0 m),
condensation will form. Insulation is recommended
and condensation drains may be desired. Venting
through the top of the heater cabinet is not
recommended if vent lengths are longer than
10' (3 m) UHD[X][S]75 only. In this case, vent from
the rear of the heater cabinet then run the vent
vertically and use a condensate drain at the bottom
of the vertical vent.
For 4'' (10 cm) common vent, an approved vent cap
(P/N 90502102) must be used.
For 6'' (15 cm) common vent, an approved vent cap
(P/N 90502103) must be used.
For common vertical venting of more than two
heaters, See Page 15, Figure 10.
A vent shall not extend less than 2' (.6 m) above the
highest point where it passes through a flat roof of a
building.
7.6 Length Requirements
If using vent lengths greater than 10' (3.0 m),
condensation will form in the vent pipe. Insulation
and additional sealing measures (high temperature
silicone at all seams) are required.
The entire vent should be insulated with foil faced
fiberglass insulation (1/2" thick, 1-1/2# density
minimum).
7.6.1 Maximum Vent Lengths Table
Model UHD[X][S] 75 - 125# of Elbows
30 ft (9.1 m)1
25 ft (7.6 m)2
20 ft (6.1 m)3
15 ft (4.5 m)4
10 ft (3.0 m)5
7.7 Vent Material
Vent material may be single wall 26 ga. (minimum)
galvanized steel or equal thickness stainless steel.
Completely seal all joints, refer to Page 11, Section
7.3.
If penetrating a combustible wall or roof, a listed
thimble with 2" (5 cm) clearance must be used.
Where local codes permit, a single section of type
B-1 vent material may be used at the roof or wall
penetration instead of a thimble. Ensure vent
manufacturer's clearance from vent material is
maintained. Seal annular space of the type B-1 vent
as well as all joints in the remaining vent.
7.8 Replacing an Existing Heater in a Venting
System
When replacing an existing heater in a venting
system, the venting system may not be properly
sized to vent the new heater. The following steps
must be followed with each piece of equipment
connected to the venting system placed in
12 of 45
Page 21
SECTION 7: VENTING
operation, while any other equipment connected to
the venting system are not in operation.
1. Seal any unused openings in the venting
system.
2. Inspect the venting system for proper size and
horizontal pitch, as required by the NFPA 54/
ANSI Z223.1 - latest revision, National Fuel
Gas Code (US) or Standard CSA B149.1
Natural Gas and Propane Installation Code
(Canada) and these instructions. Determine
that there is no blockage or restriction, leakage,
corrosion and other deficiencies which could
cause an unsafe condition.
3. Close all building doors and windows and all
doors between the space in which the piece(s)
of equipment connected to the venting system
are located and other spaces of the building.
Turn on clothes dryers and any exhaust fans,
such as range hoods and bathroom exhausts
so that they shall operate at maximum speed.
Do not operate a summer exhaust fan. Close
fireplace dampers.
4. Follow the lighting instructions. Place the
equipment being inspected in operation.
Adjust thermostat so that the equipment will
operate continuously.
5. For any equipment having a draft hood, test for
draft hood equipment spillage at the draft hood
relief opening after five minutes of main burner
operation. Use the flame of a match or candle.
6. After it has been determined that each piece(s)
of equipment connected to the venting system
properly vents when tested as outlined above,
return doors, windows, exhaust fans, fireplace
dampers and any other gas-burning piece(s) of
equipment to their previous conditions of use.
7. If improper venting is observed during any of
the above tests, the venting system must be
corrected by a contractor qualified in the
installation and service of gas-fired equipment
or your local gas supplier. If the venting must be
resized, use appropriate tables in (US)
Appendix G of NFPA 54/ANSI Z223.1 - latest
revision, National Fuel Gas Code (US) or
Standard CSA B149.1 Natural Gas and
Propane Installation Code (Canada) to
determine minimum size. All vent corrections
must be in accordance with the appropriate
local codes and the NFPA 54/ANSI Z223.1 latest revision, National Fuel Gas Code (US) or
Standard CSA B149.1 Natural Gas and
Propane Installation Code (Canada).
Figure 8: Vent and Roof Detail
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UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
Figure 9: Standard Vented Heater - Vertical and Horizontal Vent Termination
ModelVent DiameterPart Number
UHD[X] 75 - 1254" (10 cm)90502102
14 of 45
Page 23
Figure 10: Standard Vented Heater - Common Vertical Vent Termination
Type "B" vent cap
(7" [18 cm] or 8" [20 cm]) may be
SIDE VIEW
2'(.6 m)
Minimum
used. (These are not available
from the manufacurer.)
Type "B" Vent Pipe
Roof
Flashing
Roof
SECTION 7: VENTING
The last section of vent pipe passing
through the roof or wall may be Type
"B" vent pipe. All other vent materials
in the building must be single wall
vent pipe.
4" (10 cm)
Single Wall Pipe
TOP VIEW
"D"
Approved
Thimble
(If Applicable)
Single Wall Pipe
"D" Area must equal sum
of open area of
individual vents.
4" (10 cm)
Single Wall Pipe
Requirements:
• Maximum of four heaters can be commonly vented through the roof.
• Heaters must be of the same BTU output.
• Heaters must be controlled by a common thermostat.
• Connections to a common stack must be positioned to avoid direct opposition between streams of
combustion gases.
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Page 24
UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
Concentric Vent Box Top & Side Assembly905041131
Concentric Vent Box Bottom Assembly905041121
Screw #6 x 3/8 Self Drilling9111910014
4" (10 cm) Vent Terminal with Baffle Plate90502102R1
6" (15 cm) Combustion Air Terminal905021031
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UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
SECTION 8: AIR SUPPLY
WARNING
Explosion Hazard
Equipment must have access to
uncontaminated air at all times.
Failure to follow these instructions can result
in death, injury or property damage.
8.1 Separated Combustion Installation
When installed as a separated combustion heater
(UHD[X]S), the air for combustion is drawn in from
outside the building.
8.2 Building Ventilation
Where ventilation is required, air must be taken from
an outside point where it is not likely to be
contaminated or obstructed.
8.3 Outside Combustion Air Supply
If outside combustion air supply is required,
separated combustion model (UHD[X]S) heaters
must be used.
Caution: If the building has a slight negative
pressure or corrosive contaminants such as
halogenated hydrocarbons are present in the air, an
outside combustion air supply to the heater is
required. Seal all combustion air pipe joints.
The outside air terminal must not be more than 1'
(31 cm) above the vent terminal.
8.3.1 Length Requirements
Follow the constraints listed on Page 12, Section 7.6.
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Page 27
SECTION 9: GAS PIPING
SECTION 9: GAS PIPING
Fire Hazard
Connect gas supply according to Figure 14.
Do not use gas supply pipe and electrical
connections to support the heater’s weight.
Gas can leak if not installed properly.
Failure to follow these instructions can
result in death, injury or property damage.
WARNING
Explosion Hazard
Leak test all components of gas piping
before operation.
Gas can leak if piping is not installed
properly.
Do not high pressure test gas piping with
heater connected.
Failure to follow these instructions can result
in death, injury or property damage.
A gas meter is connected to the service pipe by the
gas supply company. An existing meter should be
checked, preferably by the company, to ensure that
the meter is adequate for the rate of gas supply
required.
Installation pipes must be fitted in accordance with
local and national codes. Pipes of smaller size than
the heater inlet gas connection should not be used.
Gas lines must meet applicable codes:
United States: Flexible stainless steel gas hose
(US models) is certified per the standard for
connectors for gas applications. ANSI Z21.21/CSA
6.10 – latest revision.
Canada: Rubber type 1 gas hose (Canadian
models) is certified as being in compliance with the
standard for elastomeric compostite hose and hose
couplings for conducting propane and natural gas,
CAN/CGA 8.1 – latest revision.
9.1 Connections
Connect the heater to the gas supply ensuring that
the final connections are as follows:
• Gas supply pipe work is run in medium or heavy
gauge tubing in compliance with local and
national codes.
• Meter and service must be large enough to
handle all the burners being installed plus any
other connected load. The gas pipe which feeds
the system must be large enough to supply the
required gas with a maximum pressure drop of
1/2 in wc. When gas piping is not included in the
layout drawing, contact the local gas supplier.
• An isolating valve and union connection should
be used and fitted into the supply adjacent to the
heater.
• A minimum 1/8'' NPT plugged tapping
accessible for test connection must be installed
immediately upstream of the gas supply
connection to the heater.
• For suspended heaters, an approved metal
flexible connection between the isolating valve
and the heater may be used. To reduce
pressure loss, use one pipe size larger than
the heater gas connection.
IMPORTANT - The complete installation must be
purged and tested for gas soundness in accordance
with local and national codes.
Caution: Do not high pressure (in excess of 1/2 psi
[14 in wc]) test the gas piping with the burner
connected. Close manual shut-off valve during any
pressure testing equal to or less than 1/2 psi (14 in
wc).
Check the pipe and tubing ends for leaks before
placing heating equipment into service. When
checking for gas leaks, use a soap and water
solution; never use an open flame.
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UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
Figure 14: Gas Connection
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Page 29
SECTION 10: WIRING
DANGER
Electrical Shock Hazard
Disconnect electric before service.
More than one disconnect switch may be
required to disconnect electric from
equipment.
Equipment must be properly grounded.
Failure to follow these instructions can result
in death or electrical shock.
SECTION 10: WIRING
All heater models require constant 120 V/1Ø/ 60 Hz
power supply. Check heater serial plate for electrical
rating for proper circuit sizing. For servicing, a
disconnect switch of proper electrical rating should
be installed in the vicinity of the heater.
All heaters are equipped with thermostat
connections suitable to power a 24 V thermostat.
Heater must be wired and electrically grounded in
accordance with local codes. In the absence of local
codes in accordance with: United States: refer to
National Electrical Code
®
NFPA 70 - latest revision;
Canada: refer to Canadian Electrical Code CSA
C22.1 Part I - latest revision.
10.2 Low Voltage Thermostat with One Heater
10.1 Positioning Thermostats
A room thermostat should be mounted on a
vibration-free wall or column at a height of
approximately 5' (1.5 m) from the floor to measure
the ambient temperature. It should be clear of both
cold drafts and the direct path of warm air from the
heater.
Avoid mounting thermostat on outside walls or in
areas directly exposed to radiant heat or sunlight.
Install wall tag in a visible location near thermostat.
See Page 4, Section 2.1 for wall tag details.
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UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
10.3 UHD[X][S] Series Internal Wiring Diagram
IMPORTANT:
For field wiring into service junction box, or if any of the original wire supplied with the heater
must be replaced, it must be replaced with wiring material having a temperature rating of at least 221° F
(105° C) and 600 V. For supply connections, use No. 14 AWG or larger wires.
22 of 45
Page 31
10.4 UHD[X][S] Series Ladder Wiring Diagram
SECTION 10: WIRING
IMPORTANT:
For field wiring into service junction box, or if any of the original wire supplied with the heater
must be replaced, it must be replaced with wiring material having a temperature rating of at least 221° F
(105° C) and 600 V. For supply connections, use No. 14 AWG or larger wires.
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UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
10.5 Electrical Connection to the Heater
IMPORTANT: Junction box is not provided with heater.
Conduit can also be attached directly to heater with wire junction made within the heater cabinet.
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Page 33
SECTION 11: OPERATION AND MAINTENANCE
SECTION 11: OPERATION AND MAINTENANCE
DANGER
Electrical Shock Hazard
Disconnect electric
before service.
Heater must be
connected to a properly
grounded electrical
source.
Failure to follow these instructions can result in death, electric shock, injury or property damage.
Read this manual carefully before installation,
operation, or service of this equipment. All
components are accessed via the hinged door.
Opening the door exposes live electrical
connections and hot components.
Prior to any maintenance or service of the heater,
shut off, lockout and tagout the electrical disconnect
and gas valve that supplies the unit in accordance
with OSHA regulations.
11.1 Pre-Start-Up Checks
All pre-start-up checks must be carried out before
lighting the heater.
Ensure that the heater and all controls are suitable
for the gas, pressure and electrical supply to which
they are to be connected.
Explosion Hazard
Turn off gas supply to
heater before service.
WARNING
Burn Hazard
Allow heater to cool
before service.
Tubing may still be hot
after operation.
11.2 Begin Start-Up
11.2.1 Before Operating the Heater
To ensure that all the controls are in safe working
order, operate the heater for the first time with the
isolating gas valve turned off and power supply
turned on.
1. Turn off the isolating gas valve.
2. Turn up the thermostat above room
temperature. The automatic ignition
sequence will now begin as described
on Page 26, Figure 15.
There will be no ignition of the burner and lockout
will occur, which proves the controls are operating
correctly.
Cut/Pinch Hazard
Wear protective gear
during installation,
operation and service.
Edges are sharp.
11.1.1 Electrical Checks
1. Check that all site wiring is connected in
accordance with the appropriate wiring diagram
on Page 22, Section 10.3.
11.1.2 Gas Supply
All aspects of the gas installation including the gas
meter must be inspected, tested for gas tightness
and purged in accordance with local and national
codes.
Ensure that the air is fully purged from the heater
inlet pipe up to the main gas valve inlet test nipple.
11.1.3 Mechanical Checks
1. Check that the flue (and air intake for separated
combustion units) is installed in accordance
with the instructions in this manual and local
regulations. See Page 11, Section 7.
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UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
Figure 15: Automatic Burner Control Sequence
Burner Sequence for Ignition Control
Thermostat 24 V
RUNSTART
SHUT DOWN
Flue Blower
Pressure
Switch
Ignition Spark
Start Gas Valve
Flame Signal
NO
P
C
NC
*Purge time begins at pressure switch change over.
30 Seconds Purge*
ts = 10 Seconds
Required Incoming Signals
If at any stage the flame fails, the control will retry
Signals Output By Control
for ignition. The control has four trials for ignition
before a one hour lockout.
Figure 16: Gas Valve for Models UHD[X][S] 75 – 125
30 Seconds Post
TOP VIEW
Regulator
Gas Inlet
END VIEW
Inlet Pressure
½PSIIN
C
ON
OFF
DescriptionPart Number
Gas Valve 75 – 125 NG90032505
Gas Valve 75 – 125 LP90032506
Outlet
Pressure
26 of 45
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SECTION 11: OPERATION AND MAINTENANCE
11.2.2 Start-Up the Gas Valve (All Gases)
11.2.2.1 Check Burner Gas Pressure
1. Remove the plug in the outlet (burner) pressure
test point and connect a pressure tap and a
manometer.
2. With the burner firing, measure the pressure on
the manometer. To adjust the burner pressure,
remove the regulator cover from the valve and
turn the regulator adjustment screw to set the
required burner pressure as stated in the
Technical Data Table for the correct gas and
model on Page 44, Section 16.3.
NOTE: If the correct burner pressure cannot be
reached, then check the inlet pressure to the valve
with the burner firing. See Technical Data Table on Page 44, Section 16.3 for inlet pressure
requirement.
Do not continue to adjust the regulator if the
pressure is not changing.
11.6 Complete Start-Up
Ensure that all covers are fitted correctly and all test
points are properly sealed.
11.7 Instruction to the User
Explain the controls of the heater to the user
including how to turn it on and off, using the controls
equipped on site.
Give this manual to the user.
Ensure that the user is shown and understands the
importance of maintaining clearances to
combustibles on Page 6, Figure 3, installer
responsibility on Page 4, Section 2, user
instructions on Page 28, Section 12 and all
warnings defined in this manual.
If the inlet pressure is too low to allow correct burner
pressure setting, then the gas inlet pressure must be
corrected before completing the start-up.
11.2.2.2 Check Gas Rate
1. After burner pressure adjustment, allow the
heater to operate for at least 15 minutes and
then re-check settings. Adjust pressure setting
if necessary.
2. Check gas flow rate at gas meter.
3. Turn off heater and electrical supply.
4. Remove the manometer and refit all covers to
the valve and tighten the screw of the outlet
pressure tap.
11.3 Pressure Switch
The pressure switch is factory pre-set for each
model and is not adjustable.
11.4 Turning Off the Heater
Set the thermostat to the "OFF" position or lowest
setting and the main burner will stop.
11.5 External Controls
External controls may include time switch, interlock
switch, room thermostat and frost thermostat.
Operate each control to ensure that they function
correctly. Set the switches (if equipped) and
thermostat(s) to the users’ requirements.
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UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
SECTION 12: USER INSTRUCTIONS
DANGER
Electrical Shock Hazard
Disconnect electric
before service.
Heater must be
connected to a properly
grounded electrical
source.
Failure to follow these instructions can result in death, electric shock, injury or property damage.
The UHD[X][S] Series heaters are fully automatic
and operate from the external controls fitted on site.
The only user control at the heater is the Manual
Reset Limit Switch - See Page 28, Section 12.2. See Page 40, Section 15.3 for manual reset limit
switch location inside control housing.
Explosion Hazard
Turn off gas supply to
heater before service.
WARNING
Burn Hazard
Allow heater to cool
before service.
Tubing may still be hot
after operation.
12.2 Common User Controls
12.2.1 Manual Reset Limit Switch
Cut/Pinch Hazard
Wear protective gear
during installation,
operation and service.
Edges are sharp.
WARNING
12.1 Heater Operation
When the heater has been switched on by the
thermostat installed on site, the main burner will
automatically turn on.
The burner control module will control the safe
ignition of the flame.
All heaters require a constant gas and electricity
supply which must not be interrupted during the
normal operation of this heater.
Explosion Hazard
Do not make more than one attempt to
restart the heater if manual reset limit switch
locks out.
The vent or heat exchanger may be blocked.
The fault must be traced and repaired.
Failure to follow these instructions can
result in death, injury or property damage.
The limit thermostat is located inside the hinged
access door of the heater. See Page 40, Section
15.3. This control protects against excessive heat
build-up inside the burner compartment.
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Page 37
SECTION 12: USER INSTRUCTIONS
Figure 17: Manual Reset Limit Switch
Reset Button
To reset manual reset limit switch, press reset
button. NOTE: To reset, the switch must be cool.
DescriptionPart Number
Manual Reset Limit Switch90412106
12.3 Lighting Instructions
12.3.1 To Turn On Heater
1. Ensure that the electrical and gas supplies to
the heater are on. Check that the on site
controls are "ON".
IMPORTANT: The thermostat setting must be above
the ambient temperature for the heater to operate.
12.4.1 Simple Troubleshooting (Burner Faults)
If the burner fails to ignite for any reason, it will retry
for ignition (four trials total). After four unsuccessful
ignition trials, the control will put the heater into
lockout for one hour.
Lockout should not occur during normal operation of
the heater and indicates there is a fault condition
which must be corrected. There is an LED light on
the ignition control that flashes codes to assist in
fault correction. See Page 29, Figure 18 for LED
indication codes.
Figure 18: LED Diagnostic Codes
LED INDICATION FAULT MODE
Slow FlashNormal Operation - No call for heat.
Fast FlashNormal Operation - Call for heat.
2 FlashesIgnition Lockout - No flame detected.
3 FlashesAirflow Fault - Pressure switch open or closed.
4 FlashesTemperature Limit or
Manual Reset Limit Switch Open
5 FlashesFlame Sense Error - Gas valve not energized.
Steady OnInternal Control Failure
2. The automatic firing sequence will begin as
described on Page 26, Figure 15. The heater
will now operate automatically under the control
of the on site controls.
12.3.2 To Turn Heater Off
Set the thermostat to the "OFF" position or lowest
setting. The burner will turn off immediately.
To restart, turn the thermostat on or above room
temperature.
12.4 Simple Troubleshooting
Some possible reasons for the heater not operating
are:
1. Gas supply not "ON".
2. Electricity supply not "ON".
3. The time and/or temperature controls are not
"ON".
4. A limit switch may have operated. This may be
caused by an interruption of the electrical
supply, failure of the distribution fan or vent or
heat exchanger blockage.
If a temperature limit switch persistently trips, there
is a fault which must be investigated by a contractor
qualified in the installation and service of gas-fired
heating equipment.
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UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
SECTION 13: SERVICING
DANGER
Electrical Shock Hazard
Disconnect electric
before service.
Heater must be
connected to a properly
grounded electrical
source.
Failure to follow these instructions can result in death, electric shock, injury or property damage.
13.1 Servicing Instructions
After start-up, the heater will require maintenance to
be carried out, at a minimum, annually. If the heater
is used in a dirty or dusty area, more frequent
maintenance may be required.
IMPORTANT: Prior to any maintenance or service of
the heater, shut off, lockout and tagout the electrical
disconnect and gas valve that supplies the unit in
accordance with OSHA regulations. After any
maintenance or repair work, always test fire the
heater in accordance with the start-up instructions
on Page 25, Section 11 through Page 27, Section
11.7 to ensure all safety systems are in working order
before leaving the heater to operate. Minor faults
may be traced by using the troubleshooting charts
on Page 33, Section 14 through Page 37, Section
14.5.
IMPORTANT: Check all gas pipes and pipe joints to
ensure there are no cracks or gas leaks. Any cracks
in the pipes or pipe joints must be repaired.
IMPORTANT: Inspect all suspended components
and hardware. Ensure that they are in good
condition, properly tightened, and corrosion free.
13.2 Burner Maintenance
1. Open the hinged door via tooled access and
remove from the hinges. Set door aside. See
Page 39, Section 15.2
2. Remove burner side panel. Electrode and
flame probe should remain attached. See Page 40, Section 15.3.
3. Remove burner assembly from cabinet via four
screws, two on top and two on bottom. Clean
Explosion Hazard
Turn off gas supply to
heater before service.
WARNING
Burn Hazard
Allow heater to cool
before service.
Tubing may still be hot
after operation.
any deposits from the main burner which may
have formed in the injectors or venturi of the
burner.
4. Check condition of ignition electrode and flame
probe. Clean off any deposits which may have
formed, check condition of ceramic insulators.
Replace as necessary. See Page 40, Section
15.3.
13.3 Heat Exchanger Maintenance
The heat exchanger will remain clean unless a
problem has developed with combustion. Inspect the
heat exchanger. Look for signs of overheating at the
front of the tubes which may indicate burner over
firing or persistently low air flows.
13.4 Gas Valve Maintenance
No regular maintenance is required on this device.
To change gas control valves, See Page 38, Section
15.1.
Do not repair or disassemble gas valve.
Replace faulty gas valves with replacement parts
sold and supplied by Rapid Engineering LLC.
13.5 Flue Blower
The flue blower should not require maintenance.
However, if the air pressure switch is causing burner
lockout, then remove the flue blower from the vent
box by unscrewing the screws at the mounting plate.
Screw quantity will vary by model size. Remove the
screws attaching the mounting plate to the fan inlet
See Page 41, Section 15.5. Ensure that the fan is
free to run and that the fan wheel is clean.
Cut/Pinch Hazard
Wear protective gear
during installation,
operation and service.
Edges are sharp.
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Page 39
SECTION 13: SERVICING
13.6 Venting and Air Intake Pipe
Inspect all venting and air intake pipe. Ensure that
all seams are sealed and suspension points secure.
Repair suspension points if any part of the venting
or combustion air pipe is sagging. Check to make
sure any insulation is not missing or in poor
condition. Replace as necessary. Check all venting
and air intake components to ensure they are in
good condition, gas tight and corrosion-free.
supplied by Rapid Engineering LLC and conform to
all requirements set forth in the RAPID
®
manuals
and all applicable governmental authorities
pertaining to the installation, service, operation and
labeling of the equipment.
To help facilitate optimum performance and safety,
Rapid Engineering LLC recommends that a qualified
contractor conduct, at a minimum, annual
inspections of your RAPID
®
equipment and perform
service where necessary, using only replacement
13.7 Maintenance Checklist
parts sold and supplied by Rapid Engineering LLC.
Installation Code and Annual Inspections:
All installation and service of RAPID
®
equipment
must be performed by a contractor qualified in the
installation and service of equipment sold and
Annual Fall Start-upFollow entire start-up procedure at this time and check control settings and
operation.
The Vicinity of the HeaterDo not store or use flammable objects, liquids or vapors near the heater.
Immediately remove these items if they are present.
See Page 5, Section 3.
Vehicles and Other
Objects
Maintain the clearances to combustibles.
Do not hang anything from, or place anything on, the heater.
Make sure nothing is lodged in between the heat exchanger tubes.
Immediately remove objects in violation of the clearances to combustibles.
See Page 6, Section 4.
Vent Pipe/TerminalsVenting must be intact. Using a flashlight, look for obstructions, cracks on the
pipe, gaps in the sealed areas or corrosion.
The area must be free of dirt and dust.
Remove any carbon deposits or scale using a wire brush.
If the vent terminal has a screen built in, remove any dirt, dust or deposits
from the screen.
See Page 11, Section 7through Page 18, Section 8.
Cabinet ExteriorAfter installation, touch up scratches. Periodic painting should be done there-
after as required. Warning labels and logo labels should be legible and accu-
®
rate. Please contact Rapid Engineering LLC or RAPID
independent
distributor if you need replacement warning labels or logo labels.
See Page 2, Figure 1through Page 3, Figure 2
Combustion Air Intake
Pipe
Intake pipe and inlet must be intact. Look for obstructions, cracks on the pipe,
gaps in the sealed areas or corrosion.
The area must be free of dirt and dust.
Clean and reinstall as required.
See Page 18, Section 8.
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UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
Heat ExchangerMake sure there are no cracks.
Make sure there is no sagging, bending or distortion.
Clean or replace as required.
Gas Line and Shut-off
Valves
Burner Observation
Window
Flue Blower Scroll, Wheel
Check for gas leaks.
See Page 19, Section 9.
Make sure it is clean and free of cracks or holes.
Clean and replace as required.
Compressed air or a vacuum cleaner may be used to clean dust and dirt.
and Motor
Inshot Burners and
Orifices
Clear obstructions (even spider webs will cause problems).
Carefully remove any dust and debris from the burner.
Direct-Spark IgniterReplace if there are cracked ceramics, excessive carbon residue, or erosion
of the electrode.
The electrode gap should be 1/8" (3.2 mm).
ThermostatThere should be no exposed wire or damage to the device or wiring.
See Page 21, Section 10.
Suspension PointsMake sure the heater is hanging securely.
Look for signs of wear on the suspension materials or ceiling.
See Page 9, Figure 5.
Silicone TubingEnsure tight, secure fit on all pressure fittings at pressure switch and vent box.
Gas ValveVerify that cap covering pressure regulator adjustment screw is secure and
has not been tampered with.
Verify all wiring connections.
Condensate Drain
Flush drain and clear any obstructions.
(when installed)
DuctworkConsult an indoor air quality professional for proper cleaning procedures.
Air Circulation BlowerFor a complete inspection, see the manufacturer’s installation, operation and
service manual.
Wall TagIf wall tag is present, make sure it is legible and accurate. Please contact
®
Rapid Engineering LLC or your RAPID
independent distributor if you need a
wall tag. See Page 4, Section 2.1.
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Page 41
SECTION 14: TROUBLESHOOTING
SECTION 14: TROUBLESHOOTING
DANGER
Electrical Shock Hazard
Disconnect electric
before service.
Heater must be
connected to a properly
grounded electrical
source.
Failure to follow these instructions can result in death, electric shock, injury or property damage.
Explosion Hazard
Turn off gas supply to
heater before service.
WARNING
Burn Hazard
Allow heater to cool
before service.
Tubing may still be hot
after operation.
Cut/Pinch Hazard
Wear protective gear
during installation,
operation and service.
Edges are sharp.
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UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
14.1 General
34 of 45
Page 43
14.2 Troubleshooting For Automatic Ignition Burner Systems
SECTION 14: TROUBLESHOOTING
If problems persist, contact
Bananza at
www.bananza.com
For optimum heater performance, use only replacement parts sold and supplied by Rapid Engineering
LLC. Conduct start-up procedure as shown on Page 25, Section 11.
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UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
14.3 Troubleshooting for Flame Supervision System
To measure flame current, connect a 0 - 50 µA DC meter in series with the flame probe. If the meter
reads negative values, then reverse the test leads.
START
Connect a DC ammeter in
series with the flame probe.
Is the flame present and
at least 1 µA DC flame
current?
Ye s
Is there a current flowing in
the flame probe circuit with
no flame present?
No
Does “lockout” occur when
there is a flame present?
No
Heater Operating
TROUBLESHOOT ENDS.
Use General
Troubleshooting section to
No
Ye s
Ye s
No
trace the fault.
Is the connecting lead
damaged? Is the flame probe
damaged or touching earthed
components?
Is inlet burner gas pressure
correct? Is live and neutral
polarity correct? Is
flame probe circuit correct?
No
Repair or replace as
required.
If problems persist, contact
Rapid Engineering LLC at
www.rapidengineering.com
Repair or replace as
Ye s
Ye s
required.
Replace ignition control.
NOTE: Minimum flame probe current 1 µA DC. Typical flame probe current 3-5 µA DC.
36 of 45
Page 45
14.4 Troubleshooting for Gas Valves
SECTION 14: TROUBLESHOOTING
START
Is gas pressure at inlet of the
valve correct for gas type?
Note pressure found.
Does gas pressure at outlet
of the valve rise when
valve turns on?
Does gas pressure at
outlet of valve return to zero or
lower when valve turns off?
Valve Operating
TROUBLESHOOT ENDS.
14.5 Troubleshooting for Flue Blower
Ye s
Ye s
Yes
Ye s
No
No
No
No
Fault elsewhere.
Correct pressure problem.
Valve or ignition control
faulty. Replace with
one of correct type.
Valve faulty.
Replace with one of
correct type.
If problems persist, contact
Rapid Engineering LLC at
www.rapidengineering.com
START
Does flue blower run
automatically when there
is a call for heat?
Ye s
Does blower turn on and
off while burner is firing
continously?
No
Blower Operating
TROUBLESHOOT ENDS.
No
Ye s
No
Correct power
supply problem.
Ye s
Blower motor faulty.
Replace with correct type.
Check blower motor leads
for loose connections.
If problems persist, contact
Rapid Engineering LLC at
www.rapidengineering.com
For optimum heater performance, use only replacement parts sold and supplied by Rapid Engineering
LLC.
Conduct start-up procedure as shown on Page 25, Section 11.
37 of 45
Page 46
UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
SECTION 15: REPLACEMENT PARTS
DANGER
Electrical Shock Hazard
Use only genuine RAPID® replacement parts per this installation, operation and service manual.
Failure to follow these instructions can result in death, electric shock, injury or property damage.
See warnings and notes on Page 30, Section 13
before removing or replacing parts
Burner Components
All serviceable burner parts are accessed by the
hinged door on the side of the heater.
15.1 Gas Valve
Remove the gas supply pipe at the heater inlet.
Follow instructions on See Page 39, Section 15.2 to
remove gas valve/manifold.
Explosion Hazard
WARNING
Fire Hazard
Replace in reverse order. Verify that the gas flow
direction of the valve is correct. Use a minimum
amount of gas seal on the thread joint. Check that
all the joints are leak free. Reset gas valve. See Page 27, Section 11.2.2.
IT IS IMPORTANT THAT ONLY THE CORRECT
GAS VALVE IS USED WHEN REPLACING THESE
CONTROLS.
Carbon Monoxide Hazard
.
DescriptionPart Number
Gas Valve, NG (Models UHD[X][S] 75 - 125)90032505
Gas Valve, LP (Models UHD[X][S] 75 - 125)90032506
38 of 45
Page 47
15.2 Burner Injectors
SECTION 15: REPLACEMENT PARTS
Remove four screws to remove
manifold.
Ensure gas tight fitting of orifices
Ensure correctalignment with
burners.
Ensure all pipe joints are gas tight.
MODELUHD[X][S] 75UHD[X][S] 100UHD[X][S] 125
Orifice Quantity567
Natural Gas
Orifice Marking494646
P/N919300499193004691930046
Propane
Orifice Marking1.15 mm1.25 mm1.25 mm
P/N919301159193012591930125
39 of 45
Page 48
UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
15.3 Ignition Electrode and Flame Probe
To replace the electrode or flame probe, remove the electrical lead and screw.
Pull out from mounting. Refit in reverse ensuring that the gap to burner is as shown in the front view of
the burner compartment.
The heat exchanger consists of a six-pass design with 1.5" outer diameter [aluminized steel] [409 stainless
steel] tube. The tube plates are made of [aluminized steel] [409 stainless steel]. The tube supports are
made of [aluminized steel] [409 stainless steel].
40 of 45
Page 49
15.5 Flue Blower Vertical Installation for UHD[X][S]75 Only
SECTION 15: REPLACEMENT PARTS
To remove the blower,
remove screws securing the
fan and mounting plate to
the vent box.
To remove the blower from
the mounting plate, remove
screws.
Refit in reverse order.
To change the vent and air
intake orientation from back
to top, remove the blower
and mounting plate as
above.
Remove intake and exhaust
covers from top of the
heater.
Rotate the blower, mounting
plate and gasket clockwise
until the flue adapter lines
up with the top hole. Secure
screws.
If applicable, remove the air
intake adapter from the back
of the heater and install in
the appropriate hole on top.
Install intake and exhaust
covers over the back holes.
Ensure sealed joints.
Ensure mounting plate
orifice is clear and not
obstructed.
MODELUHD[X][S] 75UHD[X][S] 100-125
Flue Blower P/N9071040490710403
IT IS IMPORTANT THAT ONLY THE CORRECT FLUE BLOWER SPECIFIED FOR EACH MODEL TYPE
IS USED WHEN REPLACING THESE ITEMS.
Carry out a start-up after working on or changing a flue blower. See Page 25, Section 11.
41 of 45
Page 50
UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
15.6 Pressure Switch
WARNING
Carbon Monoxide Hazard
Use correct pressure switch specified for each
model.
Use of incorrect pressure switch or disabling
pressure switch circuit could cause unsafe
condition.
Failure to follow these instructions can result in
death or serious injury.
Pull off 3 way connector. Spring open plastic clips of mounting cradle. Replace with correct type of pressure
switch for model. The pressure switches are color coded for each pressure setting.
Carry out a start-up after working on or changing a pressure switch. See Page 25, Section 11.
MODELUHD[X][S] 75UHD[X][S] 100UHD[X][S] 125
Pressure Switch Kit P/N
Color Code
Set Point in wc
Pressure Switch Snap Ring P/N
904398049043980590439810
whiteblueblack
0.470.550.35
904398509043985090439850
15.7 Ignition Control
The control mounts to the heat exchanger plate. Pull out ignition cable and wiring from board, noting their
positions. Release the four mounting standoffs. Refit in reverse. Ensure correct location of ignition cable
and all other wiring.
15.8 Limit Switches
15.8.1 Removal and Replacement
1. Remove the electrical connections to the switch.
2. Unscrew the two screws securing the switch.
3. Fit a new switch with two screws.
4. Reconnect the electrical connections and test operation.
42 of 45
Page 51
SECTION 16: SPECIFICATIONS
16.1 Dimension Data
SECTION 16: SPECIFICATIONS
ModelsABCDEFGHJKLMNPQR
UHD[X][S]
75
UHD[X][S]
100
UHD[X][S]
125
in cm28.7
73.0
in cm28.7
73.0
in cm28.7
73.0
17.7
45.0
22.7
57.6
22.7
57.6
22.3
56.6
22.3
56.6
22.3
56.6
17.6
44.7
17.6
44.7
17.6
44.7
18.6
47.2
18.6
47.2
18.6
47.2
2.0
5.0
2.0
5.0
2.0
5.0
6.0
2.8
15.2
7.1
6.0
2.7
15.2
6.9
6.0
2.7
15.2
6.9
6.8
2.5
17.3
6.4
8.6
21.8--
8.6
21.8--
3.3
8.4
3.3
8.4
3.3
8.4
1.9
4.8
1.9
4.8
1.9
4.8
20.3
10.4
51.6
26.4
20.3
10.4
51.6
26.4
20.3
10.4
51.6
26.4
0.6
1.5
0.6
1.5
0.6
1.5
0.5
1.4
0.5
1.4
0.5
1.4
43 of 45
Page 52
UHD LOW PROFILE DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
16.2 General Technical Data Table
ModelUHD[X][S] 75UHD[X][S] 100UHD[X][S] 125
Full Load Amps @ 120 VA122
Minimum Air VolumeCFM8509501020
Temperature Rise @ Minimum Air Volume°F (
Heat Exchanger Pressure Drop @ Minimum Air Volumein wc0.060.050.06
Maximum Air VolumeCFM265036604750
Temperature Rise @ Maximum Air Volume°F (
Heat Exchanger Pressure Drop @ Maximum Air Volumein wc0.360.550.98
Recomended Mounting Height to Heater Baseft (m)12 (3.66)20 (6.10)20 (6.10)
°C)
°C)
68 (37)78 (43)92 (51)
22 (12)22 (12)20 (11)
*Do not exceed the maximum length of flue stated or heater may not operate properly.
16.3 Technical Data Table
ModelUHD[X][S] 75UHD[X][S] 100UHD[X][S] 125
Total Input(Btu/h) x (1000)75100125
Total Output(Btu/h) x (1000)61.582102.5
Efficiency%82-All models
Natural Gas Data - Inlet Pressure 5.0 in wc Min., 14 in wc Max.
Burner Pressurein wc3.22.73.0
LPG / Propane Data - Inlet Pressure 12.0 in wc Min., 14 in wc Max.
Burner Pressurein wc10.18.99.15
44 of 45
Page 53
®
SECTION 17: RAPID
UHD-SERIES WARRANTY
RAPID ENGINEERING LLC WILL PAY FOR:
Within 24 months from date of purchase by buyer or 27
months from the date of shipment by Rapid Engineering
LLC (whichever comes first), replacement parts will be
provided free of charge for any part of the product which
fails due to a manufacturing or material defect.
Rapid Engineering LLC will require the part in question to
be returned to the factory. Rapid Engineering LLC will, at
its sole discretion, repair or replace after determining the
nature of the defect and disposition of part in question.
RAPID® Replacement Parts are warranted for a period of
18 months from date of shipment from Rapid Engineering
LLC or the remaining RAPID
®
UHD-Series warranty.
RAPID ENGINEERING LLC WILL NOT PAY FOR:
Service trips, service calls and labor charges.
Shipment of replacement parts.
Claims where the total price of the goods have not
been paid.
Damage due to:
• Improper installation, operation or maintenance.
• Misuse, abuse, neglect, or modification of the RAPID
UHD-Series in any way.
• Use of the RAPID
®
UHD-Series for other than its
intended purpose.
• Incorrect gas or electrical supply, accident, fire, floods,
acts of God, war, terrorism, or other casualty.
• Improper service, use of replacement parts or
accessories not specified by Rapid Engineering LLC.
• Failure to install or maintain the RAPID
®
UHD-Series
as directed in the Installation, Operation and Service
manual.
• Relocation of the RAPID
®
UHD-Series after initial
installation
• The use of the RAPID
®
UHD-Series in a corrosive
atmosphere containing contaminants.
• The use of the RAPID
®
UHD-Series in the vicinity of a
combustible or explosive material.
• Any defect in the RAPID
®
UHD-Series arising from a
drawing, design, or specification supplied by or on
behalf of the consumer.
• Damage incurred during shipment. Claim must be
filed with carrier.
WARRANTY IS VOID IF:
The RAPID
qualified in the installation and service of gas-fired
heating equipment.
You cannot prove original purchase date and required
annual maintenance history.
The data plate and/or serial number are removed,
defaced, modified or altered in any way.
The ownership of the RAPID
transferred. This warranty is nontransferable.
Rapid Engineering LLC is not permitted to inspect the
damaged controller and/or component parts.
®
UHD-Series is not installed by a contractor
®
UHD-Series is moved or
SECTION 17: RAPID® UHD-SERIES WARRANTY
READ YOUR INSTALLATION, OPERATION AND
SERVICE MANUAL
If you have questions about your controller, contact your
installing professional. Should you need Replacement
Parts or have additional questions, call or write:
Rapid Engineering LLC
1100 Seven Mile Road NW
Comstock Park, MI 49321
Telephone: +1.616.784.0500
Fax: +1.616.784.1910
Toll Free: 800.536.3461
www.rapidengineering.com
Rapid Engineering LLC' liability, and your exclusive
remedy, under this warranty or any implied warranty
(including the implied warranties of merchantability
and fitness for a particular purpose) is limited to
providing replacement parts during the term of this
warranty.Some jurisdictions do not allow limitations on
how long an implied warranty lasts, so this limitation may
not apply to you. There are no rights, warranties or
®
conditions, expressed or implied, statutory or otherwise,
other than those contained in this warranty.
Rapid Engineering LLC shall in no event be
responsible for incidental or consequential damages
or incur liability for damages in excess of the amount
paid by you for the RAPID
®
UHD-Series. Some
jurisdictions do not allow the exclusion or limitation of
incidental or consequential damages, so this limitation or
exclusion may not apply to you. This warranty gives you
specific legal rights, and you may also have other rights
which vary from jurisdiction to jurisdiction.
Rapid Engineering LLC shall not be responsible for failure
to perform under the terms of this warranty if caused by
circumstances out of its control, including but not limited
to war, fire, flood, strike, government or court orders, acts
of God, terrorism, unavailability of supplies, parts or
power. No person is authorized to assume for Rapid
Engineering LLC any other warranty, obligation or liability.
LIMITATIONS ON AUTHORITY OF
REPRESENTATIVES:
No representative of Rapid Engineering LLC, other than
an Executive Officer, has authority to change or extend
these provisions. Changes or extensions shall be binding
only if confirmed in writing by Rapid Engineering LLC's
duly authorized Executive Officer.
45 of 45
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