Gas Heat — Inshot Style
Performance Climate Changer™ CSAA Air Handlers
Sizes 4 to 30 for Indoor and Outdoor Units
Only qualified personnel should install and service the equipment. The installation, starting up, and servicing
of heating, ventilating, and air-conditioning equipment can be hazardous and requires specific knowledge and
training. Improperly installed, adjusted or altered equipment by an unqualified person could result in death or
serious injury. When working on the equipment, observe all precautions in the literature and on the tags,
stickers, and labels that are attached to the equipment.
October 2018
SAFETY WARNING
CLCH-SVX014B-EN
Introduction
Read this manual thoroughly before operating or servici ng
this unit.
Warnings, Cautions, and Notices
Safety advisories appear throughout this manual as
required. Your personal safety and the proper operation of
this machine depend upon the strict observance of these
precautions.
The three types of advisories are defined as follows:
WARNING
CAUTIONs
NOTICE
Important Environmental Concerns
Scientific research has shown that certain man-made
chemicals can affect the earth’s naturally occurring
stratospheric ozone layer when released to the
atmosphere. In particular, several of the identified
chemicals that may affect the ozone layer are refrigerants
that contain Chlorine, Fluorine and Carbon (CFCs) and
those containing Hydrogen, Chlorine, Fluorine and
Carbon (HCFCs). Not all refrigerants containing these
compounds have the same potential impact to the
environment. Trane advocates the responsible handling of
all refrigerants-including industry replacements for CFCs
and HCFCs such as saturated or unsaturated HFCs and
HCFCs.
Important Responsible Refrigerant
Practices
Trane believes that responsible refrigerant practices are
important to the environment, our customers, and the air
conditioning industry. All technicians who handle
refrigerants must be certified according to local rules. For
the USA, the Federal Clean Air Act (Section 608) sets forth
the requirements for handling, reclaiming, recovering and
recycling of certain refrigerants and the equipment that is
used in these service procedures. In addition, some states
or municipalities may have additional requirements that
must also be adhered to for responsible management of
refrigerants. Know the applicable laws and follow them.
Indicates a potentially hazardous
situation which, if not avoided, could
result in death or serious injury.
Indicates a potentially hazardous
situation which, if not avoided, could
result in minor or moderate injury. It
could also be used to alert against
unsafe practices.
Indicates a situation that could result in
equipment or property-damage only
accidents.
WARNI NG
Proper Field Wiring and Grounding
Required!
Failure to follow code could result in death or serious
injury. All field wiring MUST be performed by qualified
personnel. Improperly installed and grounded field
wiring poses FIRE and ELECTROCUTION hazards. To
avoid these hazards, you MUST follow requirements for
field wiring installation and grounding as described in
NEC and your local/state electrical codes.
WARNI NG
Personal Protective Equipment (PPE)
Required!
Failure to wear proper PPE for the job being undertaken
could result in death or serious injury. Technicians, in
order to protect themselves from potential electrical,
mechanical, and chemical hazards, MUST follow
precautions in this manual and on the tags, stickers,
and labels, as well as the instructions below:
•Before installing/servicing this unit, technicians
MUST put on all PPE required for the work being
undertaken (Examples; cut resistant gloves/sleeves,
butyl gloves, safety glasses, hard hat/bump cap, fall
protection, electrical PPE and arc flash clothing).
ALWAYS refer to appropriate Material Safety Data
Sheets (MSDS)/Safety Data Sheets (SDS) and OSHA
guidelines for proper PPE.
•When working with or around hazardous chemicals,
ALWAYS refer to the appropriate MSDS/SDS and
OSHA/GHS (Global Harmonized System of
Classification and Labelling of Chemicals) guidelines
for information on allowable personal exposure
levels, proper respiratory protection and handling
instructions.
•If there is a risk of energized electrical contact, arc, or
flash, technicians MUST put on all PPE in accordance
with OSHA, NFPA 70E, or other country-specific
requirements for arc flash protection, PRIOR to
servicing the unit. NEVER PERFORM ANY
SWITCHING, DISCONNECTING, OR VOLTAGE
TESTING WITHOUT PROPER ELECTRICAL PPE AND
ARC FLASH CLOTHING. ENSURE ELECTRICAL
METERS AND EQUIPMENT ARE PROPERLY RATED
FOR INTENDED VOLTAGE.
Failure to follow instructions below could result in
death or serious injury.
•All Ingersoll Rand personnel must follow Ingersoll
Rand Environmental, Health and Safety (EHS)
policies when performing work such as hot work,
electrical, fall protection, lockout/tagout, refrigerant
handling, etc. All policies can be found on the BOS
site. Where local regulations are more stringent than
these policies, those regulations supersede these
policies.
•Non-Ingersoll Rand personnel should always follow
local regulations.
Copyright
This document and the information in it are the property of
Trane, and may not be used or reproduced in whole or in
part without written permission. Trane reserves the right
to revise this publication at any time, and to make changes
to its content without obligation to notify any person of
such revision or change.
Introduction
Trademarks
All trademarks referenced in this document are the
trademarks of their respective owners.
Use this manual to install, startup, operate, and maintain
the Performance Climate Changer™ air handler gas heat
section. Carefully review the procedures discussed in this
manual to minimize installation and startup difficulties.
Nameplate
Each air handler section includes a nameplate/label which
identifies the type of section, customer tagging
information, the unit serial number, the unit order number,
the build-section position for installation, and the unit
model number.
Figure 1.Example - performance air handler section nameplate
Note: The unit serial number and order number is
required when ordering parts or requesting service
for a Trane air handler.
CLCH-SVX014B-EN5
General Information
Product Information
Model and serial numbers for the gas heat section are
designated on the nameplate located on the piping-side
access door inside the section. Record the information
below for a permanent record of the equipment installed
on your job site. The nameplate also contains the range of
Model Number____________________________________________________________________________
Serial Number_____________________________________________________________________________
Air Handler Sales Order Number____________________________________________________________
Air Handler Serial Number_________________________________________________________________
Type of Gas________________________________________________________________________________
Maximum Inlet Gas Pressure_______________________________________________________________
Minimum Inlet Gas Pressure________________________________________________________________
Temperature Rise (ºF)_______________________________________________________________________
Manifold Pressure at Maximum MBh________________________________________________________
6 CLCH-SVX014B-EN
Table 1.Motor and electrical specifications
SpecificationsGas Heater Input PowerInducer Motor
Volts115115
Hertz606060
Phase11
HPn/an/a
FLA/Ampsn/a6
(a) Powered by a “line to 115 volt” transformer for all gas heaters except 115/60/1 rated units.
Description
The gas heat section consists of an inshot tubular heat
exchanger gas train components, and a control panel for
electrical connections. It is an integral part of the entire airhandling system.
An access door is provided for service and maintenance of
the burner and gas train components.
The gas heat section must be in a blow-thru position
downstream from the supply fan. Downstream sections
must be separated by a blank access section and discharge
temperatures must be controlled so as not to exceed the
temperature limits of components in the downstream
sections.
(a)
General Information
Control Power(a)
CLCH-SVX014B-EN7
Pre-Installation
Receiving and Handling
Inspection
Upon delivery, thoroughly inspect all components for any
shipping damage that may have occurred, and confirm
that the shipment is complete. See “Receiving Checklist”
for detailed instructions.
Note: Delivery cannot be refused. All units are shipped
F.O.B. factory. Trane is not responsible for shipping
damage.
Packaging/Shipping
Gas heat sections arrive at the jobsite with an integral base
frame for the purpose of mounting units to a
housekeeping pad or roof curb. The base frame variables
in height from the standard 2.5 inches to 8 inches.
Outdoor gas heat sections ship with wooden blocks
fastened under the base channel. The blocks elevate the
section for shipping protection and ease of handling.
Leave the wooden blocks attached until the section is
placed in its final position to avoid bending the base
channel during rigging and handling.
Protective Covering
The large openings of the gas heat section are covered
with shipping protection parts. The parts are held in place
by sheet metal screws. Leave the covering attached to the
section until it is ready to install to prevent debris from
entering the section.
Flue Stack
A stainless-steel flue stack is provided with outdoor air
handlers. It ships inside the gas heat section or in one of
the other sections of the air handler, and must be mounted
on the flue opening on the side of the unit.
NOTICE
Equipment Damage!
Failure to follow this instruction could result in
equipment damage. Do not use type B flue stacks with
this product as they are not suitable for the flue gas
temperatures.
Hardware Kits
Hardware kids ship inside the air handler fan section in a
plastic bag or cardboard box. This kit contains gasketing
and screws. For outdoor units, roof joint connection strips
and wall panel seam caps are included. These are used
when fastening the gas heat section to the air handler.
Keep the hardware with the gas heat section until it is
ready to install.
Rain Hood
A rain hood is provided for outdoor units and is shipped
attached. Rain hoods for units with hurricane certifications
are shipped on a separate wood skid. A kit containing
mounting hardware ships inside the gas heat section and
must be removed before assembly to the air handler.
Instruction Manuals
Individual instruction manuals for all of the gas train
components (such as flame-control relay valves, pressure
switches, and actuators) ship inside the piping vestibule.
Retain these manual for future repair or troubleshooting.
Handling
The gas heat section is designed with the necessary
number of lift points for safe installation. The lift points are
designed to accept standard rigging devices and are
removable after installation.
Indoor sections size 4 to 30 will be shipped with a shipping
skid designed for forklift transport. If shipped on a skid, do
not remove the gas heat section from the skid at this time.
Receiving Checklist
Complete the following checklist immediately after
receiving shipment to detect possible shipping damage.
Check to ensure that the shipment is complete. Small
components may ship inside the unit or ship
separately. Check the parts list to ensure all materials
are present. If any component is missing, contact your
local Trane sales office.
Check all units, components, connections, and piping.
Check all doors, latches and hinges. Inspect interior of
each unit or section. Check for rattles, bent corners, or
other visible indications of shipping damage.
If a unit is damaged, make specific notations
concerning the damage on the freight bill. Do not
refuse delivery.
Notify the carrier’s terminal of the damage
immediately by phone and mail. Request an
immediate joint inspection of the damage by the
carrier and consignee.
Notify your Trane sales representative of the damage
and arrange for repair. Do not attempt to repair the unit
without consulting the Trane representative.
Inspect the unit for concealed damage as soon as
possible after delivery. Report concealed damage to
the freight line. It is the receiver’s responsibility to
provide reasonable evidence that concealed damage
did not occur after delivery. Take photos of damaged
material if possible.
Note: Concealed damage must be reported within 15
days of receipt.
8 CLCH-SVX014B-EN
Pre-Installation
Jobsite Storage
Indoor air handlers and field-installed accessories must be
protected from the elements. A controlled indoor
environment is recommended for proper storage.
Note: All factory shipping protection should be removed,
This wrapping is for transit protection only.
The unit controller and all other electrical/electronic
components should be stored in conditions of -20°F to
120°F and 5 to 95 percent relative humidity, noncondensing. Electrical components are not moisturetolerant.
Gas heat sections for outdoor units require no special
protection for storage prior to installation.
Outdoor Storage
NOTICE
Corrosion!
Plastic tarps can cause condensation to form in and on
the equipment, which could result in corrosion damage
or wet storage stains. Use only canvas tarps to cover air
handlers and components.
Outdoor storage is not recommended for units that will be
installed indoors. However, when outdoor storage is
necessary, several things must be done to prevent
damage:
Note: Keep the equipment on the original wooden blocks/
skid for protection and ease of handling.
•Select a well-drained area, preferably a concrete pad or
blacktop surface.
•Place the unit on a dry surface or raised off the ground
to assure adequate air circulation beneath the unit and
to assure no portion of the unit will contact standing
water at any time.
•Cover the unit securely with a canvas tarp.
•Do not stack units.
•Do not pile other material on the unit.
Trane warranty does not cover equipment damage due to
negligence during storage.
CLCH-SVX014B-EN9
Dimensions and Weights
Filter mixing box
Coil
Fan
Gas heat
Access
door
UV
lights
VFD
F
E
D
C
B
A
Service Clearances
A minimum clearance of the section width plus 12 inches
on the access door side of the gas heat section is
recommended for routine maintenance. This clearance
provides enough room to replace the heat exchanger in
the event of failure. The section side panels must be
removed to access the heat exchanger. Refer to the
following figure for service clearance recommendations
for the air handler.
Note: At a minimum, the clearance dimensions listed in
table below are recommended on one side of the
unit for regular service and maintenance. Refer to
Figure 2.Service clearance for indoor units
as-built submittal for locations of items such as
filter access doors, coil, piping connections, motor
locations, hoods, pipe cabinets, etc. Sufficient
clearance must be provided on all sides of unit for
removal of access panels, plug panels, or sectionto-section attachment brackets. Clearance for
starters, VFDs, or other high-voltage devices must
be provided per NEC requirements. For specific
dimensional and weight information, refer to the
unit submittals. The dimensions and weights in this
manual are approximate. Trane has a policy of
continuous product and product data
improvement and reserves the right to change
design and specifications without notice.
Table 2.Service clearance dimensions (in)
ComponentDescription4 6 8 10121417212530
FGas Heatn/a5663747984849292106
10 CLCH-SVX014B-EN
Table 3.Dimensions and weights
Unit SizeOutput Capacity (MBh)Length (in)Weight (lb)
Failure to properly lift unit could result in unit dropping
and possibly crushing operator/technician which could
result in death or serious injury and possible equipment
or property-only damage. Do not lift unit from top! Lift
unit from lifting lugs only located at bottom of unit.
Test lift unit approximately 24 inches to verify proper
center of gravity lift point. To avoid dropping of unit,
reposition lifting point if unit is not level.
WARNING
Heavy Objects!
Failure to follow instructions above or properly lift unit
could result in unit dropping and possibly crushing
operator/technician which could result in death or
serious injury. Ensure that all the lifting equipment
used is properly rated for the weight of the unit being
lifted. Each of the cables (chains or slings), hooks, and
shackles used to lift the unit must be capable of
supporting the entire weight of the unit. Lifting cables
(chains or slings) may not be of the same length.
Adjust as necessary for even unit lift. Other lifting
arrangements could cause equipment or property
damage.
WARNING
Hazardous Gases and Flammable Vapors!
Failure to follow all instructions could result in death or
serious injury. Exposure to hazardous gases from fuel
substances have been shown to cause cancer, birth
defects or other reproductive harm. Improper
installation, adjustment, alteration, service or use of
this product could cause flammable mixtures or lead to
excessive carbon monoxide. To avoid hazardous gases
and flammable vapors follow proper installation and
set up of this product and all warnings as provided in
this manual.
WARNING
Combustible Materials!
Failure to maintain proper clearances could result in
death or serious injury or property damage. Maintain
proper clearance between the unit heat exchanger, vent
surfaces and combustible materials. Refer to unit
nameplate and installation instructions for proper
clearances. Improper clearances could result in
combustible materials catching on fire.
Contractors’ Responsibilities
Installing Contractor
•Unpack the gas heat section and remove the skid.
•Remove protective coverings.
•Rig and/or move the section to the air handler location.
The contractor must provide slings, spreader bars,
clevis hooks, pins, etc. for rigging.
•For outdoor gas heat sections, a level roof curb or
structural steel support system is required.
•For outdoor sections, install the flue stack. The flue
must be removed from the airstream before assembly.
Install the flue stack on the gas heat section before
assembling the gas heat section to the air handler.
•Clear debris from combustion air inlets located on the
side or bottom of the gas heat section. Remove any
debris obstructing combustion air inlets.
•In areas where snow drifts are higher than the bottom
of the vestibule, a hood or louver may have to be
installed for combustion air.
•Assemble the gas heat section to the air-handling
system. Refer to CLCH-SVX07*-EN Performance
Climate Changer™ Air Handler Installation, Operation,
and Maintenance manual for specific assembly
instructions. This manual ships inside the supply fan
section of the air handler.
•Penetrate the unit casing and connect the supply gas
line to the gas train.
•For indoor gas heat sections, install a field-engineered
flue stack according to local codes.
Electrical and/or Controls Contractor
•Provide power to the gas heat section. See Wiring
chapter for power requirements.
•Provide a binary start–stop signal.
•Provide an analog 0 to 10 Vdc modulating signal. A 0 to
10 Vdc interface module is installed as standard
equipment. A 4 to 20 mA interface module is available
and may have been installed on the unit for the control
signal in lieu of the 0 to 10 Vdc signal.
•Provide an interlock in the start-stop signal circuit with
the air handler supply fan. This interlock must insure
the start-stop signal is interrupted to the gas heat
system if the supply fan is shut off. The gas heat system
must not operate without the supply fan providing
airflow.
•All wiring must comply with applicable local and
National Electric Code (NEC) specifications.
•For VAV units, provide temperature sensors for
entering and leaving air in gas heat section.
12 CLCH-SVX014B-EN
Installation
Note: All power and control wiring for the gas heat
section must be field-provided. All power and
control wiring for any section downstream of the
gas heat must be field-provided.
Lifting and Rigging
Refer to CLCH-SVX07*-EN Performance Climate
Changer™ Air Handler Installation, Operation, and
Maintenance manual for instructions on equipment
rigging and lifting. This manual ships inside the unit fan
section.
Placement and Assembly
Refer to the design engineer’s plans and submittals for the
location of the gas heat section in the air handler. The gas
heat section will arrive at the job site as an individual
section. It is not shipped with the air handler.
Hardware for fastening the gas heat section to the air
handler can be found in the unit fan section.
Final assembly of the air handler should be done at the unit
installation site. Refer to CLCH-SVX07*-EN Performance
Climate Changer™ Air Handler Installation, Operation,
and Maintenance manual for instructions on equipment
assembly.
Flue Stack for Outdoor Air Handlers
The flue stack for outdoor air handlers must be mounted
on the flue opening on the side of the unit. The flue stack
must be installed on the gas heat section before
assembling the gas heat section to the air handler. It is very
difficult to remove the flue from inside the unit once the
unit is assembled.
It is recommended that the services of an experienced,
qualified gas heat technician be employed to adjust air-fuel
ratios for proper combustion.
Installing Outdoor Flue Stacks
The flue stack for outdoor gas heat sections ships inside
the gas heat section or in one of the other sections of the
air handler.
Figure 3.Outdoor air handler flue stack
Outdoor air handler flue stack
Attach the flue stack to the flue collar and secure it with
screws as indicated in the following figure.
A field-provided rain hood or screen is recommended on
the flue to prevent possible blockage from bird nests and
beehives.
Figure 4.Outdoor air handler flue stack installation
Installation
High Altitude Installations
WARNI NG
Hazard of Explosion!
Failure to follow these instructions could result in
death or serious injury or equipment or property-only
damage. Installations at altitudes of 3,000 feet above
sea level or higher may require adjustment of the airfuel linkage for proper combustion. Air-fuel adjustment
should only be done by an experienced, qualified gas
heat technician.
Air-fuel adjustment is not normally required. However, for
high altitude installations, adjustment to the air-fuel may
be necessary for proper combustion. Heater outputs must
be derated four percent for every 1000 feet over 2000 feet
above sea level. When specifying gas heaters, the
engineer should provide the MBh and airflow required at
altitude. All Trane literature is based on nominal outputs at
sea level.
CLCH-SVX014B-EN13
Installation
Hood
Butyl tape
Attach the gas
heat flue duct
to the L angles
on both sides
Gas heat
flue
See note
L bracket
Right side view
#10 x 3/4-in.
self-drilling
sheet metal
screws
Installing Indoor Flue Stacks
Gas heat sections for indoor air handlers require a fieldengineered and field-installed flue stack. Local codes and
practices vary throughout the country. The engineer
should size the flue based on MBh output, horizontal and
vertical run lengths, type of flue material, NFPA 54 Fuel Gas
Code, and local codes. The flue should be designed for 800
degrees F (430 degrees C). If horizontal runs over 20 feet or
other static-increasing transitions are necessary, a flue
booster fan will be required.
Install according to local codes.
Installing Rain Hood/Combustion Air Inlet
Rain hoods are only required on an outdoor unit with an
internal vestibule. The combustion air opening will be in
the side panel.
Rain hoods for the combustion air opening ship attached
to the side panel or ship loose and must be installed at the
job site. The assembly consists of the hood, butyl tape and
number 10 screws.
•Install butyl tape between the hood and the side panel
or door panel. See the following figure.
Figure 5.Installation of rain hood for combustion air
opening
Figure 6.Center inlet air opening
Access door
Hinge
side
Rain hood
Airflow
2 3/8 in.
Combustion
air opening
Center hood left-to-right
over opening
Installing Flue Stack for Hurricane
Applications
Figure 7.Flue stack installation for hurricane
applications
•Locate the bottom edge of the hood 2 3/8 inches below
the bottom edge of the inlet air opening and center the
hood left-to-right over the inlet air opening. See the
following figure.
•Install the hood to the unit with number 10 screws.
14 CLCH-SVX014B-EN
Note: When installing flue, leave enough clearance to
avoid roof’s edge and anything above the roof.
Duct Connections
All duct connections to the gas heat section should be
installed in accordance with the standards of the National
Fire Protection Association (NFPA) and the Sheet Metal
and Air Conditioning Contractors National Association,
Inc. (SMACNA).
Combustion Air Duct
•Outdoor units have a rain hood that either ships
attached to the side panel or ships loose and requires
field mounting.
•All indoor units ship with a screened opening on the
combustion air inlet.
If combustion air is ducted to the vestibule, it is strongly
recommended that an experienced gas heat technician
check the system and emission levels in the exhaust flue at
start up. Carbon dioxide should be between 8.2 and 9.4
percent. This corresponds to the allowable range of excess
air needed for combustion. The additional static pressure
of the inlet air duct may change the fuel-air ratio slightly
necessitating system adjustment.
Combustion air cannot be ducted directly to the
combustion air fan. The airflow through the vestibule is
needed to keep the temperatures in the vestibule down.
Duct Transitions
When the gas heat section is the last section of the air
handler, and duct transitions should be smooth and
uniform from all sides. Follow recommendations for duct
transitions from SMACNA.
Fasten the ductwork directly to the ductwork opening.
When using lined ductwork, the insulation should not
obstruct the discharge opening.
Airflow Direction
The airflow direction through the gas heater is important
because it prevents localized “hot spots” on the heat
exchanger. Airflow direction labels denoting correct
airflow direction through the gas heat section are provided
on the burner side of the heating section. See Figure 8.
Installation
Figure 8. Airflow direction label
CLCH-SVX014B-EN15
Piping
WARNING
Hazard of Explosion and Deadly Gases!
Failure to follow all proper safe refrigerant handling
practices could result in death or serious injury. Never
solder, braze or weld on refrigerant lines or any unit
components that are above atmospheric pressure or
where refrigerant may be present. Always remove
refrigerant by following the guidelines established by
the EPA Federal Clean Air Act or other state or local
codes as appropriate. After refrigerant removal, use dry
nitrogen to bring system back to atmospheric pressure
before opening system for repairs. Mixtures of
refrigerants and air under pressure may become
combustible in the presence of an ignition source
leading to an explosion. Excessive heat from soldering,
brazing or welding with refrigerant vapors present can
form highly toxic gases and extremely corrosive acids.
Gas Piping
Note: Installation must conform with the American
National Standard Z223.1 (NFPA 54), the National
Fuel Gas Code, latest edition, in the absence of local
codes.
•Gas piping should always be done in accordance with
local codes.
•Tighten all joints securely.
•Pipe unions should be a “ground joint” type to prevent
leakage.
•Provide adequate support for field-installed piping to
avoid placing stress on the gas train and controls.
•Run takeoff lines from the side or top of the main gas
line to prevent moisture from being drawn into the gas
train of the unit.
•Provide a drip leg in the field-installed piping, installing
it near the unit.
•Select an appropriately sized gas pressure regulator to
assure the required gas supply pressure is maintained
at the unit.
•For unit to operate unit properly, the inlet gas pressure
must be maintained at 7 inches wc. Required gas
pressure to the gas train is 5 to 13 inches wc
•Gas pressure and volume must be maintained and
stable at high fire.
•If the gas pressure regulator serves more than one
heating unit, it must be sized appropriately to ensure
that the inlet gas pressure at each unit is 5 to 13 inches
wc while all burners are firing.
•Check the gas supply pressure before making the final
connection to the unit. If the gas pressure is too high,
damage to the gas valve could occur.
Heat Exchanger Condensate
Piping
Condensate usually does not form in the heat exchanger
during normal heating operation. However, if the unit
operates for extended periods of time at very low fire, or
if the air handler serves as a cooling unit also, condensate
can form in the heat exchanger and should be removed.
All units are equipped with a condensate drain. The
condensate drain is on the same side as the gas train.
If a p-trap and drain is to be connected to the condensate
drain line, consult local plumbing codes for disposal of the
condensate may be a slightly acidic solution.
Proper Gas Pressure
NOTICE
Excessive Gas Pressure!
Failure to maintain proper gas pressure could result in
damage to the gas train components. The gas pressure
at the inlet to the gas train must not exceed 13 in. wc.
A properly sized gas regulator that provides a
maximum of 13 in wc. of gas pressure, must be
supplied in the gas inlet line to unit.
•To assure sufficient gas pressure at the unit, use
appropriately sized gas pipe for unit capacity. Refer to
the National Fuel Gas Code for pipe sizing information.
16 CLCH-SVX014B-EN
Wiring
WARNING
Proper Field Wiring and Grounding
Required!
Failure to follow code could result in death or serious
injury. All field wiring MUST be performed by qualified
personnel. Improperly installed and grounded field
wiring poses FIRE and ELECTROCUTION hazards. To
avoid these hazards, you MUST follow requirements for
field wiring installation and grounding as described in
NEC and your local/state electrical codes.
WARNING
Hazardous Voltage!
Failure to disconnect power before servicing could
result in death or serious injury. Disconnect all electric
power, including remote disconnects before servicing.
Follow proper lockout/tagout procedures to ensure the
power can not be inadvertently energized.
NOTICE
Use Copper Conductors Only!
Failure to use copper conductors could result in
equipment damage.Unit terminals are not designed to
accept other types of conductors.
Wiring Checklist
•All field wiring must be in accordance with the National
Electric Code and state and local requirements.
•All wiring (including low-voltage wiring) must be
copper conductors only with the insulation rated for
600 volts.
•Refer to the nameplate located on the gas heater
section for the proper Input Voltage, Minimum Circuit
Ampacity (MCA) and Maximum Overcurrent
Protection (MOP) requirements for proper electrical
installation.
•Input voltage must be within +/- 10 percent of specified
value.
•Ground the supply power in the junction box to the
ground lead provided.
•Do not route any wires through the heat exchanger
section unless the insulation is rated for 600?F or
higher. Radiant heat from the heat exchanger will
damage wire insulation that is unsuitable for high
temperatures.
•See table in the next section for electrical
specifications.
Note: Factory wiring routed through the heated part of
the cabinet has insulation rated for 600°F.
High-Voltage Wiring
Wiring Entrance Locations
Indoor air handlers can accept conduit penetrations on
any side of the piping vestibule. For outdoor air handlers,
the recommended conduit entrance into the gas heat
section is through the floor of the piping vestibule.
Terminate conduits on the power junction box or gas
heater control panel as appropriate.
Table 4.Motor and electrical specifications
SpecificationsGas Heater Input PowerInducer Motor
Volts115115
Hertz606060
Phase11
HPn/an/a
FLA/Ampsn/a6
(a) Powered by a “line to 115 volt” transformer for all gas heaters except 115/60/1 rated units.
Single-phase 120, 208, 230, 460 or 575 volt power is
required to operate the heater controls or power the
transformer (TRANS1), if provided.
Single-phase power for 208, 230, 460, and 575 voltage is
provided for the gas heat off two legs of the three-phase
supply to the air-handling unit. A transformer in the piping
vestibule is provided to step down the voltage required for
gas heat.
CLCH-SVX014B-EN17
(a)
Control Power(a)
Wiring
Low-Voltage Wiring
NOTICE
Equipment Damage!
Do not operate the gas heat system without a supply
fan providing airflow. Operating the gas heat system
without a supply fan could result in damage to
equipment or property.
The gas heat control system requires a binary signal for
on/off control. A field provided interlock is recommended
in the start-stop signal circuit with the air handler supply
fan. This interlock must insure the start-stop signal is
interrupted to the gas heat system if the supply fan is shut
off. The gas heat system must not operate without the
supply fan providing airflow.
The control system also requires a 0 to 10 Vdc analog
signal for modulation where 10 Vdc is a signal for full heat.
18 CLCH-SVX014B-EN
Start-Up — Indirect Gas-Fired Heating
Gas Heat Application Rules — Inshot
WARNING
Hazardous Service Procedures!
Failure to follow all precautions in this manual and on
the tags, stickers, and labels could result in death or
serious injury.
•Technicians, in order to protect themselves from
potential electrical, mechanical, and chemical
hazards, MUST follow precautions in this manual and
on the tags, stickers, and labels, as well as the
following instructions: Unless specified otherwise,
disconnect all electrical power including remote
disconnect and discharge all energy storing devices
such as capacitors before servicing. Follow proper
lockout/tagout procedures to ensure the power can
not be inadvertently energized. When necessary to
work with live electrical components, have a
qualified licensed electrician or other individual who
has been trained in handling live electrical
components perform these tasks.
•Do not attempt the following procedures until all
electrical and gas connections to the unit have been
completed and the outdoor air damper and
evaporator fan operation have been verified and are
operating correctly.
Notes:
1. This furnace module does not have a pilot. It is
equipped with a direct spark ignition device that
automatically lights the gas burner. DO NOT try to light
burners by hand.
WARNING
Hazard of Explosion!
Failure to follow proper safe leak test procedures could
result in death or serious injury or equipment or
property-only-damage. NEVER use an open flame to
detect gas leaks. You MUST use a leak test solution for
leak testing.
2. BEFORE OPERATING, leak test all gas piping up to
heater gas valve. Smell around the unit area for gas. If
gas is smelled, do NOT attempt to place heater in
operation until source of gas leak is identified and
corrected.
3. Use only hand force to operate the gas control lever to
the “ON” position. NEVER use tools. If lever does not
operate by hand, replace gas valve prior to staring the
unit. Forcing or attempting to repair the gas valve may
result in fire or explosion.
4. Do not attempt to operate unit, if there is indication that
any part or control has been under water. Any control
or component that has been under water must be
replaced prior to trying to start the unit.
•The maximum allowable temperature rise is as listed
in table for minimum cfm.
•Nominal airflow is based on 500 fpm through a
nominal coil (i.e. 500 x unit size 8 = 4000 cfm).
•The minimum allowable airflow at full fire is 75 percent
of the nominal airflow (i.e. 0.75 x 500 x unit size 8 =
3000 cfm).
•The minimum allowable airflow at reduced fire is 50
percent of the nominal airflow (i.e. 0.50 x 500 x unit size
8 = 2000 cfm).
•Calculate temperature rise at airflows other than
nominal with this equation: Temp Rise = (1000 x MBh)
/ (1.1 x CFM)
•On high altitude applications, derate the heating
capacity (MBh) by 4 percent for every 1,000 feet of
altitude over 2,000 feet above sea level.
•Temperature rise is listed for nominal cfm/minimum
cfm.
Start-up Procedure
1. Check Inlet Gas Pressure:
Ensure the gas pressure supplied to the unit is within
the pressure requirement listed on the nameplate. DO
NOT expose gas controls to pressures above 13 in. wc).
If required by local code, a field provided gas supply
line should be installed with a field provided external
manual shutoff and pressure tap.
2. Verify Fan Failure Switch Operation:
The supply fan air proving switch is located in the
heater electrical control compartment near the top of
the heater panel. The switch will fail if not proven
within 30 seconds of call for indoor fan—ON. All unit
air filters must be clean before proceeding to properly
complete this verification.
Important: If the unit air filters are not clean, unit
performance could be affected. Remove
and clean or replace air filters as required
prior to proceeding with the burner
pressure testing.
Hazardous Voltage and Gas!
Failure to turn off gas or disconnect power before
servicing could result in an explosion or electrocution
which could result in death or serious injury. Turn off
the gas supply and disconnect all electric power,
including remote disconnects, before servicing the unit.
Follow proper lockout/tagout procedures to ensure the
power can not be inadvertently energized.
WARNI NG
CLCH-SVX014B-EN19
Start-Up — Indirect Gas-Fired Heating
3. Confirm Gas Flow at Unit:
Open door to unit vestibule housing the gas heater.
Move gas control lever to “OFF” position. Remove
1/8-in. pressure taps from both modulating and on-off
sections of the split heater manifold. Install a barbed
fitting in both 1/8-in. tapped holes for connection to
individual gas manometers.
Note: There is a third 1/8-in. gas pressure tap located
in the pipe connecting the main valve/regulator
and modulating valve. Maximum pressure into
modulating valve is 5-in. The On-Off gas valve
includes a regulator adjustment device that is
located on the top of the valve. Use this device
to regulate valve output to modulating valve as
required.
4. Wait 5 minutes for any gas to clear. If you smell gas,
Step 2 and correct leak. If you don’t smell gas or have
corrected any leaks, go to the next step.
5. Main Gas Supply:
Turn manual gas cock “ON”.
6. Pre-purge and Ignition:
a. Open all manual gas valves.
b. Turn power on at the gas heat switch inside the gas
heat vestibule.
c. A call for heat is initiated by the AHU unit control
through a 0-10V analog signal.
d. The heater controller will then go through a system
check to ensure that the high temperature limit and
rollout switches are closed, the air pressure switch
is open, and the modulating valve is positioned
correctly.
e. The control will then enter the pre-purge cycle,
where the inducer will run at the programmed
purge pressure. During this cycle, the control will
look for the air pressure switch to close and open at
the correct settings.
f. Once the system check and pre-purge cycles are
complete, the control will enter the ignition cycle.
The modulating valve and inducer will go to their
“light off” settings.
The DSI ignition module will be energized and the
spark ignitor will activate.
The redundant safety valve will open, allowing gas
flow.
The burners will ignite and the control will receive
a signal from the flame sensor.
The spark ignitor will remain active for the duration
of the ignition cycle, regardless of flame status.
g. If flame is not established during the ignition cycle,
the control will repeat the pre-purge and ignitions
cycles up to three times. After three failed ignition
attempts, the board will enter a 1 hour lockout.
h. Once flame has been established, the control will
enter a warm-up period to ensure flame
stabilization and reduce condensation in the heat
exchanger.
i. After the warm-up period, the control will enter the
run cycle. During the run cycle, the burner firing rate
and draft inducer pressure are determined based on
the heat demand received by the control via a 0-10V
analog signal.
Note: If the control is paired with a split manifold, Step c
through Step h pertain to the primary burners.
Once the control exits the warm-up period and the
firing rate is dictated by the rooftop control, the
control will ignite the secondary burners and
modulate the primary burners based on the
demand for heat.
j. The run cycle will continue until any of the following
conditions are met.
• The call for heat is terminated.
• Any of the safety devices (high limit, air
pressure, rollout, etc.) are triggered.
The control reaches it’s maximum run time of 6
•
hours. If this condition is reached, the control
will terminate the run cycle, continue through
the proper sequence of operations, and then
immediately enter the system check and prepurge cycles to prepare for re-ignition,
assuming conditions A and B haven't been met.
k. Once the run cycle has terminated, the redundant
safety valve will close, the modulating valve will
return to its set position, and the draft inducer will
ramp up to its “light-off” setting for a 45 second
post-purge cycle.
l. After the conclusion of the post-purge, the control
will enter the “OFF” state. All system outputs are
de-energized but all safety devices are still
monitored.
m. When the building management system
temperature is satisfied and the demand for heat
ends, the gas valve is de-energized immediately
and the combustion blower is energized on high
speed for 30-second post-purge period.
n. If the unit fails to ignite see Troubleshooting
chapte r.
20 CLCH-SVX014B-EN
Start-Up — Indirect Gas-Fired Heating
Burner flame at startup: 1.2 in. wc manifold pressure
draft inducer—high speed
Burner flame at high fire: 3.5 in. wc manifold pressure
draft inducer—high speed
Figure 9.Flame characteristics of properly-adjusted
natural gas systems
Figure 10. Flame characteristics of properly-adjusted
natural gas systems
Main Burner Flame
• The burner flame should be predominately blue in
color and well defined and centered at the tube
entry as shown in the previous figure above.
Distorted flame or yellow tipping of natural gas
flame, or a long yellow flame on propane, may be
caused by lint and dirt accumulation inside burner
or at burner ports, at air inlet between burner and
manifold pipe, or debris in the main burner orifice.
Soft brush or vacuum clean affected areas.
• Poorly defined, substantially yellow flames, or
flames that appear lazy, indicate poor air supply to
burners or excessive burner input. Verify gas
supply type and manifold pressure with rating
plate.
• Poor air supply can be caused by obstructions or
blockage in heat exchanger tubes or vent discharge
pipe. Inspect and clean as necessary to eliminate
blockage. Vacuum any dirt or loose debris. Clean
heat exchanger tubes with stiff brush. Poor flame
characteristics can also be caused by flue gas
recirculation into combustion air supply. If
surrounding buildings or prevailing winds cause
recirculation, a flue extension may be required to
prevent recirculation. Contact manufacturer prior
to making any flue adjustments.
• Reduced air delivery can also be the result of
inducer fan blade slippage, dirt accumulation in the
fan blade or low voltage to draft inducer motor.
Inspect draft fan assembly and be sure fan blade is
secure to motor shaft. Check line voltage to heater.
NOTICE
Meter Damage!
Measuring voltage with meter connect to a circuit
could result in meter damage. Do NOT measure voltage
with meter connected to a circuit.
1. Flame Sensor Current Check:
Flame current is the current which passes through the
flame from the sensor to ground. A flame signal of 0.5
to 1.0 microamp (A) is marginal. For dependable
operation, a flame signal of greater than 1.0 A is
required. To measure flame current, connect a meter
capable of reading micro-amp current so the flame
signal will be read thru the meter’s COM and A
connections. The meter should read greater than
1.0 A.
Note: If the meter reads below “0” on scale, meter
leads are reversed; disconnect power and
reconnect meter leads for proper polarity.
2. Manifold Pressure Adjustment:
• The manifold pressure for high fire second stage
should be at 3.5-in. wc, if it needs adjustment,
adjust the HI Regulator on the two stage gas valve.
• The manifold pressure for Low Fire First Stage
should be set at 1.2-in. wc, if it needs adjustment,
adjust the LO Regulator on the two stage gas valve.
CLCH-SVX014B-EN21
Start-Up — Indirect Gas-Fired Heating
Modulating
Gas Valve
Inducer Blower
Inducer Motor
Condensate Drain
(Typ 2)
Rollout Switch
Maximum Inlet
Pressure = 14 in w.c.
On/Off Gas Valve
Manifolder Gas
Pressure Tap
Component locations are approximate.
Flame
Sensor
Minimum/Maximum
Inlet Pressure =
7 in w.c./14 in w.c.
On/Off Gas Valve
Modulating Valve Inlet
Pressure Tap
Manifolder Gas
Pressure Tap
High Limit
Switch
Rollout
Switch
Ignition
Controllers
Air Proving
Switch
Safety Controls
Figure 11. Component locations
•Inducer Air Proving Switch:
A n a ir p re ss u re sw i tch is pr ov id ed as pa rt of th e c on tr ol
system to verify airflow through draft inducer by
monitoring the difference in pressure between the
draft inducer and the atmosphere. If sufficient negative
pressure is not present, indicating lack of proper air
movement through heat exchanger, the switch opens
shutting off gas supply though the ignition control
module. On units with two speed draft inducer
operation, a dual air pressure switch is used,
monitoring high and low speed pressures. The air
pressure switches have fixed settings and are not
adjustable.
The high limit switch will automatically reset when the
air temperature drops to approximately 50°F below the
limit setpoint. Determine the cause of the reduced air
flow and correct.
•Supply Fan Air Proving Switch:
A supply fan air proving switch is provided as a part of
the gas heat control system to verify air handling unit
supply fan air flow across the heat exchanger by
monitoring the difference in pressure between the gas
heat plenum section and the atmosphere. If sufficient
positive pressure is present, the switch will be closed.
The air proving switch has fixed settings and is not
adjustable.
•Rollout Switch (Manual Reset):
The furnace module is equipped with manual reset
Normal Sequence of Operation
rollout switch(es) in the event of burner flame rollout.
The switch will open on temperature rise and shut-off
gas supply through the ignition control module. Flame
rollout can be caused by insufficient airflow for the
burner firing rate (high gas pressure), blockage of the
vent system or in the heat exchanger. The furnace
module should not be placed back in operation until
the cause of rollout condition is identified and
corrected. The rollout switch can be reset by pressing
the button on top of the switch.
•High Limit Switch:
The furnace module is equipped with one or two fixed
temperature high limit switches mounted on the
vestibule panel that shuts off gas to the heater through
the ignition control module in the event of reduced
airflow over the heat exchanger tubes. Reduced airflow
can be caused by indoor fan failure, dirty or blocked
filters, or restriction of the air inlet or outlet to the unit.
22 CLCH-SVX014B-EN
The gas heat module/section goes through the following
routine every time it is started. The air handler fan must be
running.
1. A call for heat is initiated by the AHU unit control
through a 0-10V analog signal.
2. The 1285 control will then go through a system check
to ensure that the high temperature limit and rollout
switches are closed, the air pressure switch is open,
and the modulating valve is positioned correctly.
3. The control will then enter the pre-purge cycle, where
the inducer will run at the programmed purge
pressure. During this cycle, the control will look for the
air pressure switch to close and open at the correct
settings.
Start-Up — Indirect Gas-Fired Heating
4. Once the system check and pre-purge cycles are
complete, the control will enter the ignition cycle.
The modulating valve and inducer will go to their “light
off” settings.
The DSI ignition module will be energized and the
spark ignitor will activate.
The redundant safety valve will open, allowing gas
flow.
The burners will ignite and the control will receive a
signal from the flame sensor.
The spark ignitor will remain active for the duration of
the ignition cycle, regardless of flame status.
5. If flame is not established during the ignition cycle, the
control will repeat the pre-purge and ignitions cycles
up to three times. After three failed ignition attempts,
the board will enter a 1 hour lockout.
6. Once flame has been established, the control will enter
a warm-up period to ensure flame stabilization and
reduce condensation in the heat exchanger.
7. After the warm-up period, the control will enter the run
cycle. During the run cycle, the burner firing rate and
draft inducer pressure are determined based on the
heat demand received by the control via a 0-10V analog
signal.
Note: If the control is paired with a split manifold, steps 1
through 6 pertain to the primary burners. Once the
control exits the warm-up period and the firing rate
is dictated by the rooftop control, the control will
ignite the secondary burners and modulate the
primary burners based on the demand for heat.
8. The run cycle will continue until any of the following
conditions are met.
a. The call for heat is terminated.
b. Any of the safety devices (high limit, air pressure,
rollout, etc.) are triggered.
c. The control reaches it’s maximum run time of 6
hours. If this condition is reached, the control will
terminate the run cycle, continue through the
proper sequence of operations, and then
immediately enter the system check and pre-purge
cycles to prepare for re-ignition, assuming
conditions A and B haven't been met.
9. Once the run cycle has terminated, the redundant
safety valve will close, the modulating valve will return
to its set position, and the draft inducer will ramp up to
its “light-off” setting for a 45 second post-purge cycle.
10. After the conclusion of the post-purge, the control will
enter the “OFF” state. All system outputs are
de-energized but all safety devices are still monitored.
11. Operation will continue in high-fire mode until the
signal from the building management controller drops
to below 4.7 VDC. At this point the gas heat control
module de-energizes the second stage gas valve and
the combustion blower switches to low speed.
12. When the building thermostat is satisfied and the
demand for heat ends, the gas valve is de-energized
immediately the combustion blower is energized on
high speed for 30-second post-purge period.
Normal Shutdown
The air-handling unit fan should run for a minimum of
three to ten minutes after heater shutdown to cool the heat
exchanger.
CLCH-SVX014B-EN23
Wiring Diagrams
Figure 12. Typical wiring diagram for 5:1 turndown heater
24 CLCH-SVX014B-EN
Figure 13. Typical wiring diagram for 10:1 turndown heater
Wiring Diagrams
CLCH-SVX014B-EN25
Wiring Diagrams
Figure 14. Typical wiring diagram for 20:1 turndown heater
26 CLCH-SVX014B-EN
Routine Maintenance
WARNING
Hazardous Gases and Flammable Vapors!
Failure to follow all instructions could result in death or
serious injury.Exposure to hazardous gases from fuel
substances have been shown to cause cancer, birth
defects or other reproductive harm. Improper
installation, adjustment, alteration, service or use of
this product could cause flammable mixtures or lead to
excessive carbon monoxide. To avoid hazardous gases
and flammable vapors follow proper installation and set
up of this product and all warnings as provided in this
manual. Failure to follow all instructions could result in
death or serious injury.
Table 5.Routine maintenance for trained service personnel
TaskFrequencyRemarks
Clean drain from heat exchanger AnnuallyRequired only if the unit runs for extended hours at low fire.
Clean air inlet louver/screenMonthlyUse brush and vacuum cleaner.
Clean inducer blower and motor AnnuallyUse brush and vacuum cleaner.
Clean exhaust flueAnnuallyUse brush and vacuum cleaner.
Check combustion air inlets for
obstruction. Remove debris
Check gas piping for leaks AnnuallyUse soap bubble solution or equivalent leak tester.
AnnuallyUse brush and vacuum cleaner.
Hazardous Voltage!
Failure to disconnect power before servicing could
result in death or serious injury. Disconnect all electric
power, including remote disconnects before servicing.
Follow proper lockout/tagout procedures to ensure the
power can not be inadvertently energized.
Hazard of Explosion!
Failure to follow proper safe leak test procedures could
result in death or serious injury or equipment or
property-only-damage. NEVER use an open flame to
detect gas leaks. You MUST use a leak test solution for
leak testing.
WARNI NG
WARNI NG
CLCH-SVX014B-EN27
Troubleshooting Guide
WARN ING
Hazardous Service Procedures!
Failure to follow all precautions in this manual and on
the tags, stickers, and labels could result in death or
serious injury.
Technicians, in order to protect themselves from
potential electrical, mechanical, and chemical hazards,
MUST follow precautions in this manual and on the
tags, stickers, and labels, as well as the following
instructions: Unless specified otherwise, disconnect all
electrical power including remote disconnect and
discharge all energy storing devices such as capacitors
before servicing. Follow proper lockout/tagout
procedures to ensure the power can not be
inadvertently energized. When necessary to work with
live electrical components, have a qualified licensed
electrician or other individual who has been trained in
handling live electrical components perform these
tasks.
WARN ING
Hazardous Gases and Flammable Vapors!
Failure to observe following instructions could result in
death or serious injury. Exposure to hazardous gases
from fuel substances have been shown to cause cancer,
birth defects or other reproductive harm. Improper
installation, adjustment, alteration, service or use of
this product could cause flammable mixtures or lead to
excessive carbon monoxide. To avoid hazardous gases
and flammable vapors follow proper installation and
set up of this product and all warnings as provided in
this manual.
28 CLCH-SVX014B-EN
Table 6.Troubleshooting guide for VB1285 modulating control
FailureCodeDescription of SymptomActions
1. Ensure there is no voltage to gas valve—repair/replace wiring if
E083 or 4Flame is detected without call for heat
E0428
E0529
E0111F ailed ignition, retries have been exhausted
E027Primary limit or limit switch failure
E18Unexpected flame (split manifold burners)
Air pressure sensor reading low and/or
pressure switch failed to open
Air pressure sensor readin g high and/or
pressure switch failed to close
voltage is present.
2. If voltage is not present , check for gas flow. If gas is flowi ng, verify
line and manifold pressures before replacing valve.
1. Failed combustion blower.
2. Check pressure hoses for leaks or blockage.
3. Check for blockage in the inducer barb fitting.
4. Check for condensate accumulation in the pressure switch and
hose.
5. Check the pressure switch wiring.
6. Replace the pressure switch.
1. Check wiring to the pressure switch and draft inducer.
2. Replace the pressure switch.
1. Verify gas supply available and manifold pressure is correct.
2. Verify the gas valve is in the ON position.
3. Verify that a spark in present; if not check igniter for debris
between the electrodes, for cracked ceramic and check ignition
wire for cracks.
4. Check to see if the sensor ceramic is cracked or if the electrode
wire is coated with dirt or oils.
5. Check to see if the flame sensor wire is connected properly and not
grounded due to wire abrasions.
6. Check for air leaks.
7. Check for re-circulation of flue product.
1. Determine which switches are open using an OHM meter.
2. If limit switch is open, check temperature rise and airflow over the
heat exchanger.
3. If high limit does not reset with proper airflow, change limit.
4. If rollout switch is open check for flue vent blockage or air leaks
in the cabinet.
5. Reset the rollout switch and observe the flame for signs of rolling
out.
1. Unplug flame sensor, replace sensor if error corrects.
2. Is there voltage to the gas valve with no call for heat? Remove
voltage source, rewire.
3. Check for excessive gas line pressur e. Install regulator if high gas
pressure.
4. Replace gas valve.
5. If rollout switch is open, check for flue vent blockage or air leaks
in the cabinet.
6. Reset the rollout switch and observe the flame for signs of rolling
out.
Troubleshooting Guide
VB1285 Sequence of Operations
1. A call for heat is initiated by the rooftop unit control
through a digital Modbus signal or the analog
thermostat.
2. The VB1285 control will then go through a system
check to ensure that the high temperature limit and
rollout switches are closed, the air pressure switch is
open, and the modulating valve is positioned correctly.
3. The control will then enter the pre-purge cycle, where
the inducer will run at the programmed purge
pressure. During this cycle, the control will look for the
air pressure switch to close and open at the correct
settings.
CLCH-SVX014B-EN29
4. Once the system check and pre-purge cycles are
complete, the control will enter the ignition cycle.
a. The modulating valve and inducer will go to their
“light off” settings.
b. The DSI ignition module will be energized and the
spark ignitor will activate.
c. The redundant safety valve will open, allowing gas
flow.
d. The burners will ignite and the control will receive
a signal from the flame sensor.
e. The spark ignitor will remain active for the duration
of the ignition cycle, regardless of flame status.
5. If flame is not established during the ignition cycle, the
control will repeat the pre-purge and ignitions cycles
Troubleshooting Guide
up to three times. After three failed ignition attempts,
the board will enter a 1 hour lockout.
6. Once flame has been established, the control will enter
a warm-up period to ensure flame stabilization and
reduce condensation in the heat exchanger.
7. After the warm-up period, the control will enter the run
cycle. During the run cycle, the burner firing rate and
draft inducer pressure are determined based on the
heat demand received by the control via a Modbus
signal or the analog thermostat.
Note: If the control is paired with a split manifold, steps 1
through 6 pertain to the primary burners. Once the
control exits the warm-up period and the firing rate
is dictated by the rooftop control, the control will
ignite the secondary burners and modulate the
primary burners based on the demand for heat.
8. The run cycle will continue until any of the following
conditions are met.
Table 7.Troubleshooting guide for VB1287
FailureCodeDescription of SymptomActions
eFLAME_SPLIT21Flame is detected without call for heat
eAIR_FLOW_LOW
eAIR_FLOW_HIGH
eAIR_ZERO_LO
eAIR_ZERO_HIGH
eNO_IGNITION_PRIME
eNO_IGNITION_SPLIT1222
eFLAME_DROP_OUT_PR
IMARY
eFLAME_DROP_OUT_SP
LIT
4344Low pressure switch is open
High pressure switch is open
41Low pressure switch closed at start
High pressure switch closed at start
Primary burner exceeds a number of trials
for ignition
Split burner exceeds nu mber of tri als for
ignition, primary burner remains
operational
Primary burner flame loss count exceeds
33
a threshold
Split burner flame loss count exceeds a
23
threshold
a. The call for heat is terminated.
b. Any of the safety devices (high limit, air pressure,
rollout, etc.) are triggered.
c. The control reaches it’s maximum run time of 6
hours. If this condition is reached, the control will
terminate the run cycle, continue through the
proper sequence of operations, and then
immediately enter the system check and pre-purge
cycles to prepare for re-ignition, assuming
conditions A and B haven't been met.
9. Once the run cycle has terminated, the redundant
safety valve will close, the modulating valve will return
to its set position, and the draft inducer will ramp up to
its “light-off” setting for a 45 second post-purge cycle.
10. After the conclusion of the post-purge, the control will
enter the “OFF” state. All system outputs are deenergized but all safety devices are still monitored.
1. Ensure there is no voltage to gas valve—repair/replace wiring if
voltage is present.
2. If voltage is not present, check for gas flow. If gas is flowing, verify
line and manifold pressures before replacing valve.
1. Failed combustion blower.
2. Check pressure hoses for leaks or blockage.
3. Check for blockage in the inducer barb fitting.
4. Check for condensate accumulation in the pressure switch and
hose.
5. Check the pressure switch wiring.
6. Replace the pressure switch.
1. Check wiring to the pressure switch and draft inducer.
2. Check pressure switch for closed contact using an OHM meter.
3. Replace the pressure switch.
1. Verify gas supply available and manifold pressure is correct.
2. Verify the gas valve is in the ON position.
3. Verify that a spark in present; if not check igniter for debris
between the electrodes, for cracked ceramic and check ignitio n
wire for cracks.
4. Check to see if the sensor ceramic is cracked or if the electrode
wire is coated with dirt or oils.
5. Check to see if the flame sensor wire is connected properly and n ot
grounded due to wire abrasions.
6. Check for air leaks.
7. Check for re-circulation of flue product.
1. Check to see if the sensor ceramic is cracked or if the electrode
wire is coated with dirt or oils. Clean or replace.
2. Check to see if the senor wire is connected properly and not
grounded due to wire abrasions.
3. Check for re-circulation of flue product.
4. Check to see if the flame is unstable or floating away from the
senor.
5. Check that all burner components are assembled correctly and all
seals are tight.
30 CLCH-SVX014B-EN
Table 7.Troubleshooting guide for VB1287 (continued)
FailureCodeDescription of SymptomActions
ePRIMARY_LIMIT51
eGAS_VALVE_HI_PRIME
eGAS_VALVE_HI_SPLIT
eGAS_VALVE_HI_PRIME
_SPLIT
Primary limit and/or rollout switches are
open
Prime burner staging failure. Gas valve is
15
in the incorrect state.
25
Split burner staging failure. Gas valve is in
the incorrect state.
35
Both the split and primary gas valves are
in the incorrect state.
Troubleshooting Guide
1. Determine which switches are open using an OHM meter.
2. If limit switch is open, check temperature rise and airflow over the
heat exchanger.
3. If high limit does not reset with proper airflow, change limit.
4. If rollout switch is open, check for flue vent blockage or air leaks
in the cabinet.
5. Reset the rollout switch and observe the flame for signs of rolling
out.
1. Check gas valve wiring.
2. Check for shorts in 24V circuit.
3. Replace control.
VB1287 Sequence of Operations
1. A call for heat is initiated by the rooftop unit control
through a digital Modbus signal or the analog
thermostat.
2. The VB1287 control will then go through a system
check to ensure that the high temperature limit and
rollout switches are closed, the air pressure switch is
open, and the modulating valve is positioned correctly.
3. The control will then enter the pre-purge cycle, where
the inducer will run at the programmed purge
pressure. During this cycle, the control will look for the
air pressure switch to close and open at the correct
settings.
4. Once the system check and pre-purge cycles are
complete, the control will enter the ignition cycle.
a. The inducer will go to its “light off” setting (usually
high speed).
b. The DSI ignition module will be energized and the
spark ignitor will activate.
c. The safety valve will open, allowing gas flow.
d. The burners will ignite and the VB1287 control will
receive a signal from the flame sensor.
8. The run cycle will continue until any of the following
9. Once the run cycle has terminated, the redundant
10. After the conclusion of the post-purge, the control will
control exits the warm-up period and the firing rate
is dictated by the rooftop control, the control will
ignite the secondary burners and step High or Low
the primary burners based on the demand for heat.
conditions are met.
a. The call for heat is terminated.
b. Any of the safety devices (high limit, air pressure,
rollout, etc.) are triggered.
c. The control reaches it’s maximum run time of 6
hours. If this condition is reached, the control will
terminate the run cycle, continue through the
proper sequence of operations, and then
immediately enter the system check and pre-purge
cycles to prepare for re-ignition, assuming
conditions A and B haven't been met.
safety valve will close, the modulating valve will return
to its set position, and the draft inducer will ramp up to
its “light-off” setting for a 45 second post-purge cycle.
enter the “OFF” state. All system outputs are deenergized but all safety devices are still monitored.
e. The spark ignitor will remain active for the duration
of the ignition cycle, regardless of flame status.
5. If flame is not established during the ignition cycle, the
control will repeat the pre-purge and ignition cycles up
to three times. After three failed ignition attempts, the
board will enter a 1 hour lockout.
6. Once flame has been established, the control will enter
a warm-up period to ensure flame stabilization and
reduce condensation in the heat exchanger.
7. After the warm-up period, the control will enter the run
cycle. During the run cycle, the burner firing rate is
determined by the heat demand received by the
control via a Modbus signal or the analog thermostat.
Two firing stages, High or Low, are available.
Note: If the control is paired with a split manifold, steps 1
through 6 pertain to the primary burners. Once the
CLCH-SVX014B-EN31
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