Reznor CAUA User manual

Form O-CAUA, P/N 164772 R4, Page 1
Operation, Maintenance, and Service
Form O-CAUA (Version A)
Obsoletes Form O-CAUA
�
FOR YOUR SAFETY
If you smell gas:
1. Open windows.
2. Don't touch electrical switches.
3.Extinguishanyopename.
4. Immediately call your gas supplier.
Theuseandstorageofgasolineorotherammablevapors
and liquids in open containers in the vicinity of this appli-
ance is hazardous.
WARNING: Improper installation, adjustment, alteration,
service, or maintenance can cause property damage, injury,
or death. Read the installation, operation, and maintenance
instructions thoroughly before installing or servicing this
equipment.
WARNING: Gas-red appliances are not designed for use
inhazardousatmospherescontainingammable vapors or
combustible dust. See Hazard Levels on page 2.
KEEP THIS BOOKLET FOR MAINTENANCE
AND SERVICE REFERENCE.
Model CAUA
with Optional Cased
Cooling Coil
A
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CQS
CQS
Applies to: Model CAUA
Gas-Fired Indoor
Vertical(Upow),
Power-Vented Heater

Form O-CAUA, Page 2
2. MAINTENANCE A Model CAUA will operate with a minimum of maintenance. To ensure long life
and satisfactory performance, a heater that is operated under normal condi-
tions should be inspected and cleaned at the start of each heating season. If
the heater is operating in an area where an unusual amount of dust, soot, or
other impurities are present in the air, more frequent maintenance is recom-
mended. If the system includes a cooling coil, the coil and condensate drains
should be checked at the beginning of the cooling season.
The paragraphs that follow discuss the components and systems that require
routine inspection/maintenance. At the beginning of each section, there is a
code indicating the main reason why that maintenance procedure is neces-
sary. The legend for that code is shown on the left.
WARNING: If you
turn off the power
supply, turn off the
gas. See Hazard
Levels, Page 2.
HAZARD INTENSITY LEVELS
1. DANGER: Failure to comply will result in severe personal injury or death
and/or property damage.
2. WARNING: Failure to comply could result in severe personal injury or
death and/or property damage.
3. CAUTION: Failure to comply could result in minor personal injury and/or
property damage.
1. General The operation/maintenance/service instructions in this manual apply to Reznor®
Model CAUA upow, separated-combustion, gas-red heater. As with any gas-
burning equipment, regular maintenance procedures are required to ensure
continued safety, reliability, and efciency of the installation.
If service is required, this heater should be serviced only by a qualied service
technician. Service information is this booklet is intended as a guideline for a
qualied gas-red equipment service technician.
2.1 Maintenance
Schedule
The following procedures should be carried out at least annually. Follow the
instructions in Paragraph 2.2.
• Clean the blower and motor. If equipped with a belt drive, check the belt.
• Check the lters.
• Check the gas valve to ensure that gas ow is being shutoff completely.
• Check the burners for scale, dust, or lint accumulation.
• Check the ignitor
1. General ....................................................2
2. MAINTENANCE ....................................2-7
2.1 Maintenance Schedule..................... 2
2.2 Maintenance Procedures.................. 3
2.2.1 Blower and Blower Motor .........................3
2.2.2 Filters ........................................................3
2.2.3 Gas Valve..................................................4
2.2.2 Filters (cont'd)............................................4
2.2.4 Burner Maintenance..................................5
2.2.5 Ignition System..........................................6
2.2.6 Cleaning the Heat Exchanger ...................7
2.2.7 Venter Motor and Wheel ...........................7
2.2.8 Vent or Vent/Combustion Air System ........7
2.2.9 Condensate Drain .....................................7
3. SERVICE - Control Location,
Operation, and Service......................7-15
3.1 Control Locations.............................. 8
3.2 Heater Rating Plate .......................... 8
3.3 Service Procedures .......................... 8
3.3.1 Operating Gas Valve .................................8
3.3.2 Ignition System..........................................8
3.3.3 Combustion Air Proving Switch.................9
3.3.3 Limit Control ............................................10
3.3.4 Flame Rollout Switch ..............................10
3.3.5 Venter Motor and Wheel Assembly .........10
3.3.6 Transformer.............................................11
3.3.7 Blower Motor and Drive...........................12
3.3.8 Blower Compartment Door Switch .........12
3.3.9 Inlet Air Dampers and Controls ..............12
3.4 Troubleshooting.............................. 14
INDEX.........................................................16
REFERENCES ...........................................16
TABLE OF CONTENTS

Form O-CAUA, P/N 164772 R4, Page 3
2.2.1 Blower and
Blower Motor RRemove dirt and grease from the motor and the blower. Use care when
cleaning to prevent causing misalignment or imbalance. If the unit is equipped
with a belt drive, check the belt for signs of wear. Replace if needed.
Check the belt tension. Proper belt tension is important to the long life of the
belt and motor. A loose belt will cause wear and slippage. Too much tension
will cause excessive motor and blower bearing wear. Adjust the belt tension by
turning the adjusting screw on the motor base until the belt can be depressed
3/4" (19mm). (See FIGURE 1.) After correct tension is achieved, re-tighten the
locknut on the adjustment screw and recheck belt alignment.
FIGURE 1 - Check
Belt Tension


Code Reason for Maintenance
S
= Safety (to avoid personal injury and/or property damage)
R= Continued Reliability
E
= Efcient Operation
2.2 Maintenance
Procedures
• Clean the venter
• Clean the heat exchanger both internally and externally.
• Check the vent or vent/combustion air system
• Check the wiring for any damaged wires. Replace damaged wiring.
• If equipped with a cooling coil, check the drain lines. Clean as needed.
NOTE: Use only factory-authorized replacement parts.
2.2.2 Filters RE Check the lters quarterly. Clean or replace as needed. Replace-
ment P/N's for lters are listed here with application by size listed below.
2" Pleated Filters 2" Permanent Filters 2" Disposable Filters
16x16, P/N 104109 16x16, P/N 104103 (Btm Filter Cabinet only)
12x32, P/N 114324 12x16, P/N 114325 16x16, P/N 104101
16x20, P/N 101620 16x20, P/N 101620
1" x 16" x 25" Filters for Inlet Base only (Size 350 and 400 only)
Disposable - P/N 16447; Permanent - P/N 101609; Pleated - P/N 104107
(Applies to a heater
with either an
optional return air
ltercabinet;an
outside air/return
air mixing box with
lters;oraninlet
basewithlters.) Sizes & Quantities of Filters Used in Return Air Filter Cabinet
To replace lters, select replacement P/N's from the list above for type and size
of lters. If using eld-replacement lters, replace with same size and type.
TABLE 1A -
Replacement Filters
for Return Air Filter
Cabinet
For Full Size Filter Cabinet on
Either Side of the Heater For Small Filter Cabinet on
Either Side or Rear of Heater
Size Permanent or Pleated
150, 200, 250, 300 (4) 16x16 - 2" Filters Size CFM FPM 2" Filters
350, 400 (6) 16x16 - 2" Filters Pleated Permanent
For Full Size Filter Cabinet on Rear of Heater
150
1800 375 (2) 12x32 (4) 12x16
Size Permanent or Pleated 2400 500 (2) 12x32 (4) 12x16
150, 200 (4) 16x16 - 2" Filters *3000 625 -- (4) 12x16
250, 300, 350, 400 (6) 16x16 - 2" Filters 200 2400 500 (2) 12x32 (4) 12x16
For Filter Cabinet on Bottom of Heater *3000 625 -- (4) 12x16
Size Permanent, Pleated, or
Disposable Filters *Application requires 2" permanent; do not
use pleated lters.
150, 200 (6) 16x16 - 2" Filters
250, 300 (8) 16x16 - 2" Filters
350, 400 (12) 16x16 - 2" Filters

Form O-CAUA, Page 4
2.2.3 Gas Valve
Single-Stage
Valve
Two-Stage
Valve
1/8" INLET
Pressure Tap
1/8”
Outlet
Pressure
Tap
1/8" INLET
Pressure Tap
1/8”
Outlet
Pressure
Tap
FIGURE 2
2) With the manual valve turned off to prevent ow to the gas valve, connect a
manometer to the 1/8” inlet pressure tap in the valve. NOTE: A manometer
(uid-lled gauge) with an inches water column scale is recommended.
3) With the eld-installed manual valve remaining closed, observe the
manometer for two to three minutes for an indication of gas pressure. No
pressure should be indicated on the manometer.
If the manometer indicates a gas pressure, the eld-installed manual
gas valve must be replaced or repaired before the combination gas valve
can be checked.
4) If the manometer does not indicate gas pressure, slowly open the eld-
installed manual gas valve. After the manometer's indicated gas pressure
has reached equilibrium, close the manual shutoff valve. Observe the gas
pressure. There should be no loss of gas pressure on the manometer. If
the manometer indicates a loss of pressure, replace the combination gas
valve before placing the heater in operation.
WARNING: The operating valve is the prime safety shutoff.
All gas supply lines must be free of dirt or scale before
connecting to the unit to ensure positive closure. See Hazard
Levels, page 2.
Instructions:
1) Locate the
1/8” FPT
INLET pres-
sure tap on
the combina-
tion valve
(See FIGURE
2, right).
2. Maintenance
(cont'd)
2.2 Maintenance
Procedures
(cont'd)
SRemove external dirt accumulation and check wiring connections.
The combination gas valve must be checked annually to ensure that the valve
is shutting off gas ow completely.
TABLE 1B -
Replacement Filters
and Blockoff Plates
for Mixing Box
Sizes and Quantities of Filters (2" Permanent or 2" Pleated only)
and Blockoff Plates Used in the Optional Outside Air/Return Air
Mixing Box
To replace lters, select replacement P/N's from the list on page 3 for type and
size of lters in TABLE 1B. If using eld-replacement lters, replace with same
size and type.
TABLE 1B - Replacement Filter Quantity and Sizes for Mixing Box
Size Filters - (Qty) Size Filter Blockoff Plate
150, 200 (2) 16 x 16; (2) 16 x 20 (1) P/N 123226
250, 300, 350, 400 (6) 16 x 16 (1) P/N 114337
CAUTION: DO NOT
bottom out the gas
valve regulator
adjusting screw.
This can result
in unregulated
manifold pressure
causing excess
overreandheat
exchanger failure.
Sizes and Quantities of Filters (1" only) Used in the Optional Inlet
Base (Option AVA2 for Sizes 350 and 400 only)
Each base requires eight lters (or only six if one side is blocked off). Filters are
1" x 16" x 25"; P/N's for each type of lter are listed in the table on page 3.
2.2.2 Filters (cont'd)

Form O-CAUA, P/N 164772 R4, Page 5
2.2.4 Burner
Maintenance WARNING: Excessive dirt buildup on and inside the burner
ports could cause fuel gas to spill out of the back of the burn-
er tube causing gas odor inside the building. If uncorrected,
fuel spilling out of the back of the burner tube could cause a
reorexplosion.Topreventfuelgasfromspillingfromthe
back of the burners, check the burner ports at least annually
and clean if necessary.
FIGURE 3 - View of
Control Compartment
with Access Panel
and All Sections of
the Burner Cover
Removed (Wires
and tubing are not
illustrated.)
















Excessive dirt buildup on and inside the ports on a burner could cause fuel gas
to spill out of the back of the burner tube. Fuel gas spilling out of the back of a
burner tube will cause gas odor inside the building, and if not corrected, could
eventually cause a re/explosion hazard. To prevent fuel gas spilling from the
back of a burner tube, check the burner ports at least annually and clean if nec-
essary. Remove any soot deposits from the burners with a wire brush. Clean
the ports with an aerosol degreaser and/or compressed air. Wipe the inside
of the burner tubes clean. (Cleaning the burners with an aerosol degreaser is
highly recommended as the degreaser will retard future buildup of dirt.)
SInstructions for Burner Rack Removal (See FIGURE 3.)
1. Shut the gas supply off upstream of the combination valve.
2. Turn off the electric supply.
3. Remove the burner compartment door.
4. Disconnect the union and remove the gas pipe from the inlet of the gas valve.
5. Mark and disconnect the electrical wires to the gas valve. Disconnect the ame sensor wire, the
ame rollout switch wires, and the ignitor wire at the burner box cover. Mark and disconnect the
ignitor ground wire at the terminal board.
6. Disconnect the silicone tubing from the static tap on the burner box cover.
7. Remove all burner cover sections. Depending on when the unit was manufactured, there will be
either two or three sections. If two, there will be a right and left section which extend over the front. If
three, there will be right, left, and a separate front section.
8. Remove the screws that attach the manifold to the burner rack. Slide the manifold from the burner
rack. Remove the screws at the ends of the burner rack that attach it to the cabinet. Carefully pull the
burner rack away from the heater.
CAUTION: Use of eye protection is recommended.
Clean the Burner
Rack and Manifold
(requires a wire
brush, cleaning cloth,
an automotive type
aerosol degreaser or
refrigerant coil cleaner,
and compressed air)

Form O-CAUA, Page 6
RThis heater is equipped with a direct spark integrated control system. The
ignition board monitors the safety devices and controls the operation of the
blower and venter motors and the gas valve.
Ignition System Operating Sequence
On a call for heat from the thermostat, the system energizes the venter motor
and goes through a 10-second prepurge. The system veries that the pressure
switch has changed states closing the normally open contactor and that the
high limit is in the closed state.
The gas valve is then energized, and the ignition system provides the high volt-
age spark to the electrode to ignite the main burner gas. Burner ame is elec-
tronically sensed by the control (minimum 1.0 microamps) upon carryover of all
burners. (A separate solid metal probe is used as the ame sensing function. A
low voltage electrical signal is imposed on the metal probe which is electrically
isolated from ground. When the ame impinges on the ame sensing probe,
the ame acts as a conduction path to ground. The ame recties and com-
pletes the DC circuit, and the ignition system acknowledges the ame.)
The blower motor is energized after 30 seconds of ame sensing.
After the thermostat has been satised, the system de-energizes the gas valve,
the venter motor goes through a 45-second post-purge, and the blower motor
remains energized for an additional 135 seconds.
NOTE: This is a three trial system. The unit will lockout for one hour before ini-
tiating another trial for ignition. If the unit fails after one recycle interval, the unit
will go into hard lockout and must be reset by interrupting power or resetting
the thermostat. To initiate another trial for ignition before the one hour interval,
either reset the thermostat or interrupt power to the unit for 30 seconds.
Maintenance: To access the ignition system, follow Steps 1-3 in Paragraph
2.2.4.
Ignitor - On the right side of the burner rack, locate the ignitor. Disconnect
the wire; remove the screw and the ignitor. Clean the ignitor assembly with an
emery cloth.
Spark gap must be maintained to 1/8". See FIGURE 6,page 9.
IMPORTANT: When re-assembling, the brown ground wire must remain
attached to the ignitor.
CAUTION: Due to high voltage on the spark wire and electrode, do
not touch when energized. See Hazard Levels, Page 2.
Flame Sensor - On the left side of the burner rack, locate the ame sensor.
Disconnect the wire; remove the screw and the ame sensor. Clean with an
emery cloth.
Ignition Control - The integrated ignition control module monitors the opera-
tion of the heater including ignition. Do not attempt to disassemble the igni-
tion control module. However, each heating season the lead wires should be
checked for insulation deterioration and good connections.
Proper operation of the direct spark ignition system requires a minimum
amesignalof1.0microampsasmeasuredbyamicroampmeter.
2. Maintenance
(cont'd)
2.2 Maintenance
Procedures
(cont'd)
2.2.4 Burner Maintenance (cont'd)
2.2.5 Ignition System
Inspect the cleaned burner rack for any damage or deterioration. If a burner
has any damage or signs of deterioration, replace it.
Clean the burner orices with air pressure. Do not ream orices.
Re-assemble the heater and test for proper operation.

Form O-CAUA, P/N 164772 R4, Page 7
ETo clean the outer surfaces (circulating air side) of the heat exchanger,
gain access by removing the inspection panels in the ductwork or removing
the ductwork. Use a brush and/or an air hose to remove accumulated dust and
grease deposits.
The inner surfaces of the heat exchanger can be reached for cleaning with the
burner, turbulators and venter assembly removed. Follow instructions in Para-
graph 2.2.4 to remove the burner (See FIGURE 3).
Remove the turbulators (Turbulators are the metal strips inside the heat
exchanger tubes). Clean the inside of the tubes with a long furnace brush or
a heavy wire to which steel wool has been attached. Brush inside each heat
exchanger tube until all foreign material is removed. A ashlight is helpful in
examining the inside of the tubes. Clean turbulator strips, slide into end of
tubes, and re-attach using the screws removed.
If operating with natural gas, there should be no soot deposits. For operation
with propane gas, if sooting exists, check for improper gas manifold pressure
and for obstructions in the vent.
If the unit is installed as a power vent (drawing combustion air from inside the
building) and dirt is found in the tubes indicating a dirty environment, installa-
tion of a separated combustion/venting system should be considered.
RRemove dirt and grease from the motor housing. The venter motor is per-
manently lubricated; do not lubricate. Carefully clean the venter wheel assem-
bly, being cautious not to bend the wheel.
S
R
Check at least once a year. Inspection should include all joints,
seams, and the terminal caps. Clean any screens and grills. Replace any
defective parts.
2.2.6 Cleaning
the Heat Exchanger
CAUTION: Eye
protection is
recommended.
2.2.7 Venter Motor
and Wheel
2.2.8 Vent or Vent/
Combustion Air
System
2.2.9 Condensate
Drain ERIf the installation has condensate drains (burner, cooling coil, and/or
ue wrapper),.clean or replace parts as needed. Fill traps.
3. SERVICE -
Control
Location,
Operation, and
Service
WARNING: Service work on this heater should only be done
by a qualied gas service technician. The service informa-
tion and the troubleshooting guides are intended as an aid to
aqualiedservicetechnician.
WARNING: Should overheating occur, or the gas supply fail
to shut off, turn off the manual gas valve to the appliance be-
fore shutting off the electrical supply.
WARNING: Do not use this appliance if any part has been un-
derwater.Immediatelycallaqualiedservicetechnicianto
inspect the appliance and replace any gas control which has
been under water.
WARNING: If you turn off the power supply, turn off the gas.
See Hazard Levels, Page 2.

Form O-CAUA, Page 8
Time
Delay
Relay
Ignition Control
Module
(Circuit Board)
Terminal Strip
Relay
Contactor
or Starter
Thermostat
Terminal
Strip
Pressure
Switch
Transformer
FIGURE 4 - Control
Locations in
the Electrical
Compartment
(Remove the control
compartment access
panel)
3.1 Control
Locations
To service this heater, it is necessary to understand the normal operating functions of
the heater controls. Refer to FIGURE 4 to identify and locate the controls.
3.2 Heater Rating
Plate
The heater rating plate is a quick reference for information about a heater
and its installation requirements. In addition, the Serial No. on the rating plate
identies components used in manufacturing that specic heater. The serial
number is coded to identify the gas valve and ignition type that was installed
on the heater at the time of manufacture. This information is required if service
and/or replacement parts are required.
Follow the example below to decode the heater Serial No.
Example: Heater Serial No. BIC78Q3N12345
BIC 78 Q3 N 12345
Month and Year Safety Pilot Code Type of Type of Consecutive
of Manufacture (Type of Ignition) Valve Gas* Number
* N = Natural Gas; L = Propane Gas
NOTE: In addition to the
rating plate, each heater
has a "Replacement
Parts Label" attached that
identies parts specic to
that heater, as well as the
Model and Serial No. of
the heater.
IMPORTANT: The serial number code can only identify the original equipment.
Before servicing, check for a gas conversion label.
When inquiring about replacement parts, always provide the complete Model
No. and Serial No.
3.3.1 Operating Gas
Valve
Function: The gas valve automatically controls the gas ow to the main burn-
ers and regulates the gas pressure.
Service: The valve has no eld-repairable parts. Carefully remove external dirt
accumulation from the valve and check wiring connections.
Refer to Form I-CAUA, Paragraph 6.1, for instructions on checking manifold
pressure.
The gas valve must be checked annually to ensure that the valve is shutting off
gas ow completely; see Maintenance Paragraph 2.2.3.
Gas
Valve
3.3 Service Procedures
3.3.2 Ignition System Function: The heater is equipped with a direct-spark integrated control sys-
tem. The system monitors the safety devices and controls the operation of the
blower and venter motors and the gas valve.
Control Module: The control module is an integrated board located in the
control compartment. Supply and control wiring connects into the control mod-
ule. The module has an LED troubleshooting light which identies operating
problems. The control module also acts as a fan control energizing the fan 30
3. SERVICE - Control Location, Operation, and Service (cont'd)

Form O-CAUA, P/N 164772 R4, Page 9
FIGURE 5 - Integrated
Ignition Control
Module, P/N 195573
Control Status - Green LED
Steady ON Normal Operation, No call for heat
Fast Flash Normal Operation, Call for heat
1 Flash System Lockout, Failed to detect or sustain ame
2 Flashes Pressure Switch in Open Position
3 Flashes High Limit or Flame Rollout Switch Open
4 Flashes Pressure Switch is closed before venter is energized
Steady Off Internal Failure - Replace the ignition control module
Flame Status - Yellow LED
Steady On Flame is sensed
Slow Flash Weak Flame
Fast Flash Undesired Flame
Fan Delay to
OFF Switch (DIP
Switch Settings -
selected prior to
call for heat)
SW1 SW2 Fan Delay To OFF (seconds)
OFF OFF 120
OFF ON 90
ON OFF 160 (Factory Preset)
ON ON 45
Ignitor Connection
seconds after ignition and delaying fan shutdown for 160 seconds after the gas
valve closes. See FIGURE 5 for LED codes and fan delay dip switch settings.
NOTE: This control is on units manufactured beginning 3/09. To replace an
ignition controller on a unit manufactured prior to 3/09, order kit P/N 258251.
FIGURE 6 -
Spark Gap
Front View
of Ignitor
showing
Spark Gap
Measurement
Ignitor
Flame Sensor: The ame
sensor is located on the left
side of the burner assembly.
Instructions for cleaning and
checking the ame sensor
are included in Paragraph
2.2.5.
Service: The direct spark integrated circuit board is polarity sensitive. If burn-
ers cycle on and off, try switching the power supply leads. The supply connec-
tion made to "L1" on the circuit board must be the "hot" wire.
If it is determined that any of the components of the ignition system require
replacing, use only the factory-authorized replacement parts that are designed
for this heater.
Function: The combustion air proving switch is a pressure sensitive switch
that monitors air pressure to ensure that proper combustion air ow is avail-
able. The switch is single pole/double throw with the normally open contacts
closing when a decreasing pressure is sensed in the system.





Ignitor: The ignitor is located on the right side of the burner assembly. Instruc-
tions for cleaning and checking the ignitor are included in the Paragraph 2.2.5.
The spark gap shown in FIGURE 6 must be maintained.
3.3.3 Combustion Air
Proving Switch
Pressure
Switch On start-up when the heater is cold, the sensing pressure is at the most nega-
tive level, and as the heater and ue system warm up, the sensing pressure
becomes less negative. After the system has reached equilibrium (about 20
minutes), the sensing pressure levels off.
If a restriction or excessive ue length or turns cause the sensing pressure to
be outside the switch setpoint, the pressure switch will function to shut off the
main burners. The main burners will remain off until the system has cooled
and/or the ue system resistance is reduced. The table below lists the approxi-
mate water column negative pressure readings and switch setpoints for sea
level operating conditions.

Form O-CAUA, Page 10
3. SERVICE - Control Location, Operation, and Service (cont'd)
3.3 Service Procedures (cont'd)
Model Size Start-Up Cold Equilibrium Setpoint “OFF” Setpoint “ON”
150 1.45 1.05 .75 .90
200 1.50 1.05 .75 .90
250 1.55 1.10 .75 .90
300 1.60 1.15 .75 .90
350 1.30 1.05 .75 .90
400 1.20 1.00 .75 .90
Function: The limit control is a temperature sensitive safety device that will
shut down the gas valve if a temperature above the setpoint is sensed. The
limit control is an automatic reset type with a capillary sensor. When the tem-
perature drops below the setpoint, the limit control deactivates allowing opera-
tion of the heater. The capillary sensor extends across the heat exchanger
section of the unit sensing the temperature of the discharge air.
TABLE 2 - Pressure
Switch Setpoints
(sea level)
DANGER:Safeoperationrequiresproperventingow.NEVERbypassthecombustion
air proving switch or attempt to operate the unit without the venter running and
theproperowintheventsystem.Hazardousconditionscouldresult.SeeHazard
Levels, Page 2.
3.3.3 Limit
Control
3.3.4 Flame Rollout
Switch
TABLE 4 -Flame Rollout Switch
CAUA Size P/N Setting
150-200 112752 225°F
250-300 121275 275°F
350-400 112752 225°F
3.3.5 Venter Motor
and Wheel Assembly
Service: Check the tubing that connects the pressure switch and the venter.
If the tubing is blocked or deteriorated, clean or replace. Be sure that the con-
nections are tight.
If it is determined that the pressure switch needs replacing, use only the fac-
tory-authorized replacement part that is designed for this heater. For location,
see FIGURE 4, page 7. Never bypass the pressure switch.
TABLE 3 -
Limit Controls
For CAUA Sizes P/N Length Setpoint
150, 200, 350, 400 148588 60" (1524mm) 270°F
250, 300 164792 54" (1372mm) 300°F
Service: If it is determined that the limit control needs replacing, use only the
factory-authorized replacement part that is designed for the size of heater (see
P/N's above). The limit control is accessible in the control compartment. The
capillary sensor can only be reached by removing the ductwork.
Function: The ame rollout switch is a temperature-activated manually reset,
limit switch. The switch is mounted on the side of the burner box in a position
that senses temperature in a central horizontal location at the rear of the burner
assembly.
If the ame rollout switch activates to shutdown the heater, the cause must be
corrected.
Service: If it is determined that the ame
rollout switch needs replacing, use only the
factory-authorized replacement part that is
designed for use on this heater (see P/N's
in the TABLE 4).
Function: The venter assembly provides a metered ow of combustion air
to the burner and exhausts the products of combustion to the outside atmo-
sphere.