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© 2025 Lennox Industries Inc.
Dallas, Texas USA
WARNING
This furnace is equipped with an ignition control
factory enabled for use with Lennox A2L refrigerant
systems.
Disabling
functionality on A2L system is prohibited by safety
codes. Refer to furnace installation instructions for
non-A2L and non-Lennox refrigerant system setup.
Table of Contents
Unit Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Parts Arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
SL280UHNVK Gas Furnace . . . . . . . . . . . . . . . . . . . . . . . 4
Shipping and Packing List . . . . . . . . . . . . . . . . . . . . . . . . 4
Safety Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Use of Furnace as a Construction Heater . . . . . . . . . . . 5
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Combustion, Dilution & Ventilation Air . . . . . . . . . . . . . . 6
Setting Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Duct System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Gas Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
the
refrigerant
detection
INSTALLATION
INSTRUCTIONS
SL280UHNVK
DAVE LENNOX SIGNATURE
GAS FURNACE UPFLOW / HORIZONTAL
AIR DISCHARGE
508561-01
01/2025
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
This is a safety alert symbol and should never be
ignored. When you see this symbol on labels or in man-
uals, be alert to the potential for personal injury or death.
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, personal
injury or loss of life. Installation and service must be
performed by a licensed professional HVAC installer (or
equivalent), service agency or the gas supplier.
A thermostat is not included and must be ordered
separately.
A Lennox communicating thermostat may be used in
communicating applications.
In
non-communicating
conventional thermostat may be used, as well as other
non-communicating thermostats.
In all cases, setup is critical to ensure proper system
operation.
Field
wiring
for
communicating applications is illustrated in diagrams,
which begin on Page 24.
Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Ignition Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Blower Performance Data . . . . . . . . . . . . . . . . . . . . . . . . 40
Low GWP Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Unit Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Proper Combustion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
High Altitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Other Unit Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Heating Sequence of Operation . . . . . . . . . . . . . . . . . . . 47
Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Repair Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Program Unit Capacity Size / Code . . . . . . . . . . . . . . . 53
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Page 1
®
WARNING
NOTICE
applications,
any
both
communicating
Lennox
and
non-
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Related Manuals for Lennox SIGNATURE SL280UHNVK Series
Summary of Contents for Lennox SIGNATURE SL280UHNVK Series
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Page 1: Table Of Contents
NOTICE A thermostat is not included and must be ordered separately. WARNING A Lennox communicating thermostat may be used in communicating applications. This furnace is equipped with an ignition control non-communicating applications, Lennox... -
Page 2: Unit Dimensions
Unit Dimensions - inches (mm) NOTE - 60C and 60D size units that require air volumes over 1800 cfm must have one of the following: 1. Single side return air and Optional Return Air Base with transition that must accommodate required 3-1/8 (79) 20 x 25 x 1 inch (508 x 635 x 25 mm) air filter to maintain proper velocity. -
Page 3: Parts Arrangement
Parts Arrangement Heat Exchanger Combustion Air Inducer Gas Valve Screen Reducer 2” PVC Pipe 2 ½” Length Elbow Intake Air Elbow Control Box (includes integrated control, Inner Access Access Panel interlock switch and transformer) Panel Blower Assembly Power Choke (4 and 5 Ton Only) FIGURE 1 Page 3... -
Page 4: Sl280Uhnvk Gas Furnace
Certifications SL280UHNVK Gas Furnace SL280UHNVK units are CSA International certified to The SL280UHNVK gas furnace is equipped with a two- ANSI Z21.47. stage, variable speed integrated control. The control is compatible with: In the USA, installation of gas furnaces must conform with local building codes. -
Page 5: Use Of Furnace As A Construction Heater
Use of Furnace as Construction Heater When this furnace is used with cooling units, it shall be Lennox does not recommend the use of SL280UHNVK installed in parallel with, or on the upstream side of, cool- units as a construction heater during any phase of con- ing units to avoid condensation in the heating compart- struction. -
Page 6: General
CAUTION General These instructions are intended as a general guide and do Insufficient combustion air can cause headaches, not supersede local codes in any way. Consult authorities nausea, dizziness or asphyxiation. It will also cause having jurisdiction before installation. excess water in the heat exchanger resulting in rusting In addition to the requirements outlined previously, the and premature heat exchanger failure. -
Page 7: Unconfined Space
Unconfined Space Air from Inside An unconfined space is an area such as a basement or If the confined space that houses the furnace adjoins a large equipment room with a volume greater than 50 cubic space categorized as unconfined, air can be brought in by feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of the com- providing two permanent openings between the two spac- bined input rating of all appliances installed in that space. - Page 8 EQUIPMENT IN CONFINED SPACE ALL AIR FROM OUTSIDE (Inlet Air from Crawlspace and Outlet Air to Ventilated Attic) CHIMNEY OR GAS VENT VENTILATION LOUVERS (Each end of attic) OUTLET WATER FURNACE HEATER INLET VENTILATION LOUVERS (For unheated crawl space) AIR FLOW NOTE-The inlet and outlet air openings shall each have a free area of at least one square inch (645 ) per 4,000 Btu (1.17 kW) per hour of the total input rating of all equipment in the enclosure.
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Page 9: Setting Equipment
Upflow Applications Setting Equipmet Allow for clearances to combustible materials as indicated WARNING on the unit nameplate. Minimum clearances for closet or alcove installations are shown in FIGURE 8. Do not install the furnace on its front or its back. Do Upflow Application Installation Clearances not connect the return air ducts to the back of the furnace. - Page 10 Return Air -- Upflow Applications Single Side Return Air Return air can be brought in through the bottom or either (with transition and filter) side of the furnace installed in an upflow application. If the furnace is installed on a platform with bottom return, make an airtight seal between the bottom of the furnace and the platform to ensure that the furnace operates properly and safely.
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Page 11: Removing The Bottom Panel
Pivot the bottom cap down to release the bottom applications. Order kit number 51W10 (or use equivalent) panel. Once the bottom panel has been removed, reinstall from Lennox. the bottom cap. See FIGURE 11. Allow for clearances to combustible materials as indicated on the unit nameplate. -
Page 12: Filters
Before using any filter with this system, check the specifications provided by the filter manufacturer against the data given in the appropriate Lennox Product Specifications bulletin. Additional information is provided in Service and Application Note ACC002 (August 2000). - Page 13 Intake Piping The SL280UHNVK must have the provided air intake SUPPLY screen assembly installed. The assembly may be rotated Install self tapping screws to seal any potential air if necessary to accommodate furnace installation. leaks Follow the next two steps when installing the air intake pipe with screen.
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Page 14: Venting
Use self-drilling sheet metal screws or a mechanical fas- Venting tener to firmly secure the vent pipe to the round collar of A 4-inch diameter flue transition is factory-installed on the the flue transition. If self-drilling screws are used to attach combustion air inducer outlet of all models. - Page 15 IMPORTANT Common Venting Using Metal-Lined Masonry Chimney SINGLE appliance venting of a fan-assisted furnace into SEALED a tile-lined masonry chimney (interior or outside wall) is PROHIBITED. The chimney must first be lined with MAX. LENGTH -- SEE NOTE 1 either type B1 vent or an insulated single wall flexible BELOW.
- Page 16 A type B1 vent or masonry chimney liner shall terminate 7 - Single appliance venting configurations with zero above the roof surface with a listed cap or a listed roof as- lateral lengths are assumed to have no elbows in the sembly according to the terms of their respective listings vent system.
- Page 17 14 - All venting pipe passing through floors, walls, and 18 - The common vent diameter must always be at least ceilings must be installed with the listed clearance as large as the largest vent connector diameter. to combustible materials and be fire stopped 19 - In no case, shall the vent connector be sized more according to local codes.
- Page 18 TABLE 4 Vent Connector Capacity Type B Double-Wall Vents with Type B Double-Wall Connectors Serving Two or More Category I Appliances Vent and Connector Diameter - D (inches) Height Lateral 3 inch 4 inch 5 inch 6 inch Appliance Input Rating in Thousands of Btu Per Hour (feet) (feet) TABLE 5...
- Page 19 Removal of the Furnace from Common Vent 3 - Close all building doors and windows and all doors between the space in which the appliances In the event that an existing furnace is removed from a remaining connected to the common venting system venting system commonly run with separate gas applianc- are located and other spaces of the building.
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Page 20: Gas Piping
3 - The gas piping must not run in or through air ducts, Gas Piping clothes chutes, gas vents or chimneys, dumb waiters, or elevator shafts. CAUTION 4 - The piping should be sloped 1/4 inch (6.4 mm) per 15 feet (4.57 m) upward toward the meter from the If a flexible gas connector is required or allowed by the furnace. -
Page 21: Leak Check
Left Side Piping MANUAL (Standard) MAIN SHUT-OFF AUTOMATIC MANUAL VALVE GAS VALVE MAIN SHUT-OFF (With 1/8 in. NPT AUTOMATIC VALVE Plugged Tap GAS VALVE (With 1/8 in. NPT Shown) Plugged Tap Shown) GROUND JOINT UNION GROUND JOINT UNION DRIP LEG Right Side Piping FIELD (Alternate) -
Page 22: Electrical
IMPORTANT Electrical When matching this gas furnace with zoning, ELECTROSTATIC DISCHARGE (ESD) defrost tempering stat or other 24V accessories, Precautions and Procedures It is recommended to replace the factory installed CAUTION transformer with kit 27J32. Electrostatic discharge affect Kit 27J32 contains a 75VA transformer, so you do electronic components. - Page 23 The factory default is based upon 400 CFM a ton. For optimal performance in non-communicating applica- tions, Lennox recommends use of a ComfortSense high Generator Use - Voltage Requirements quality electronic digital thermostat or any other with ad-...
- Page 24 Communicating Enabled Furnace and Non- Communicating Enabled Furnace and Communicating Outdoor Unit Communicating Enabled Outdoor Unit COMMUNICATING FURNACE COMMUNICATING FURNACE OPTIONAL DISCHARGE AIR SENSOR OPTIONAL DISCHARGE AIR SENSOR OPTIONAL OUTDOOR OPTIONAL COMMUNICATING AIR SENSOR OUTDOOR THERMOSTAT AIR SENSOR COMMUNICATING THERMOSTAT DOOR AIR CONDITIONING OR HEAT PUMP UNIT NON-COMMUNICATING...
- Page 25 Optional Accessories for use with any Communicating System NOTE: ICOMMUNICATING THERMOSTAT SENSES HUMIDITY & CONTROLS HUM CONTACTS TO CYCLE HUMIDIFIER BASED 120V CONNECTIONS “HUM” CONTACT IS QUIRED. CLOSED ANYTIME HUMIDITY DEMAND IS PRESENT TIONS. BUILT INTO ALL COMMUNICATING ENABLED OUT DOOR UNITS).
- Page 26 LENNOX COMMUNICATING OUTDOOR UNIT INDOOR UNIT (1 OR 2 STAGE) FLOAT SWITCH LENNOX COMMUNICATING OUTDOOR UNIT LENNOX COMMUNICATING FURNACE EL297VK, SL280VK, SL280VNK, SL297VK, SLP99VK cutting DS to R will not cause communication interuption or error code CUT* R-DS W914 FIGURE 27...
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Page 27: Ignition Control
Ignition Control TWO STAGE, VARIABLE SPEED, COMMUNICATING 107899- FIGURE 28 TABLE 8 TABLE 10 1/4”QUICK CONNECT TERMINALS THERMOSTAT INPUT TERMINALS 120 VAC OUTPUT TO HUMIDIFIER LOW STAGE HEAT XMFR 120 VAC OUTPUT TO TRANSFORMER HIGH STAGE HEAT 120 VAC INPUT TO CONTROL CIRC 120 VAC OUTPUT TO CIRCULATING BLOWER LOW STAGE COOL... -
Page 28: Wiring Connections
TABLE 12 DIP Switch Settings and On-Board Links DIP Switch 1 On Board Links Must Be Cut To Select Thermostat Thermostat Wiring Connections System Options Heating Stages 1 Heat / 1 Cool FURNACE OUTDOOR T'STAT TERM. STRIP UNIT NOTE - Use DIP switch 2 to set second-stage heat ON delay. - Page 29 TABLE 12 Con DIP Switch Settings and On-Board Links DIP Switch 1 On Board Links Must Be Cut To Select Thermostat Thermostat Wiring Connections System Options Heating Stages 2 Heat / 2 Cool FURNACE OUTDOOR (M30 T-stat) T'STAT TERM. STRIP UNIT CUT ON-BOARD LINK W915...
- Page 30 TABLE 12 Con DIP Switch Settings and On-Board Links DIP Switch 1 Wiring Connections Thermostat On Board Links Must Be Cut To Select Thermostat Heating System Options Stages Dual Fuel FURNACE HEAT PUMP T'STAT TERM. STRIP Single Stage Heat Pump CUT ON-BOARD LINK (M30 T-stat) W951...
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Page 31: System Options
TABLE 12 Con DIP Switch Settings and On-Board Links DIP Switch 1 Wiring Connections Thermostat On Board Links Must Be Cut To Select Thermostat Heating System Options Stages Dual Fuel FURNACE HEAT PUMP T'STAT TERM. STRIP Single Stage Heat Pump CUT ON-BOARD LINK (M30 T-stat) W951... -
Page 32: Wiring Diagram
Wiring Diagram BLACK 120VAC PURPLE YELLOW COMBUSTION AIR BLOWER MOTOR XFMR CIRC WHITE WHITE DOOR IGNITOR INTERLOCK HUMIDIFIER CIRC FLAME SENSE FLAME SENSOR WHITE BLACK 120V WHITE BLUE BLUE YELLOW MV COM ORANGE PURPLE PURPLE S128 HI/LOW HEAT PRESSURE SWITCH BLUE RO(OUT) BLUE... -
Page 33: Ignition Control Diagnostic Codes
Ignition Control Diagnostic Codes DIAGNOSTIC CODES / STATUS OF FURNACE CODE IDLE MODE (DECIMALBLINKS AT 1 HERTZ -- 0.5 SECONDS ON, 0.5 SECONDS OFF INDOOR BLOWER OPERATION: CONTINUOUS FAN MODE (COSTANT TORQUE ONLY) INDOOR BLOWER OPERATION: FOLLOWED BY CFM SETTING FOR INDOOR BLOWER (1 SECOND ON, 0.5 SECOND OFF) / CFM SETTING FOR MODE DISPLAYED (VARIALBE SPEED ONLY) COOLING STAGE (1 SECOND ON, 0.5 SECOND OFF) 1 OR 2 DISPLAYED / PAUSE / REPEAT CODES. - Page 34 Ignition Control Diagnostic Codes (continued) SOFT LOCKOUT FAULTS (60 MINUTES) UNABLE TO COMMUNICATE WITH CIRCULAR MOTOR E201 GAS VALVE RELAY (1ST OR 2ND STAGE) CONTACT SHORTED E205 HOT SURFACE IGNITOR (HSI) SENSED OPEN E207 SOFT LOCKOUT-FLAME FAILURE ON IGNITION, IGNITION RETRY>MAX, LAST FAILED RETRY DUE TO FLAME E270 FAILURE SOFT LOCKOUT-PRESSURE SWITCH OPEN, IGNITION RETRY>MAX, LAST FAILED RETRY DUE TO LPSW OPEN...
- Page 35 TABLE 13 Integrated Control DIP Switch Settings - Blower Off Delay Switch Settings Conventional Thermostat (non-communicating) Blower Off Delay Switch 3 Switch 4 SL280UHNVK units are equipped with a two-stage, vari- Seconds able speed integrated control. This control manages igni- tion timing, heating mode fan off delays and indoor blower 90 (factory) speeds based on selections made using the control dip...
- Page 36 TABLE 16 Ramping Option D Cooling Mode Blower Speed Ramping • Motor runs at 100% until demand is satisfied. • Once demand is met, motor ramps down to stop. Ramping Switch 9 Switch 10 A (Factory) 100% CFM COMPRESSOR DEMAND Switches 11, 12 and 13 -- Heating Mode Blower Speed The switches are factory set to the OFF position which Ramping Option A (Factory Selection)
- Page 37 Diagnostic LED (FIGURE 28) On-Board Links The seven-segment diagnostic LED displays operating Note: In communicating systems with a conventional out- status, target airflow, error codes and other information. door unit (non-communicating), the on-board clippable links must be set to properly configure the system. Diagnostic Push Button (FIGURE 28) WARNING The diagnostic push button is located adjacent to the sev-...
- Page 38 TABLE 19 OPERATING SEQUENCE SL280UHNVK, Non-Communicating Thermostat with Humidity Control Feature and Single-Speed Outdoor Unit OPERATING SEQUENCE SYSTEM DEMAND SYSTEM RESPONSE Thermostat Demand Relative Humidity Blower System Compre Step Comments ssor Condition Status (cool) NO CALL FOR DEHUMIDIFICATION Compressor and Normal Operation Acceptable High...
- Page 39 TABLE 20 OPERATING SEQUENCE SL280UHNVK, Non-Communicating Thermostat with Humidity Control Feature and Two-Speed Outdoor Unit OPERATING SYSTEM DEMAND SYSTEM RESPONSE SEQUENCE Thermostat Demand Relative Humidity Blower System Compre Step Comments ssor Condition Status (cool) NO CALL FOR DEHUMIDIFICATION Normal Operation Acceptable 70%* Compressor and indoor...
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Page 40: Blower Performance Data
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan Only speed is selectable at 28% and 38% of the selected second stage cooling speed - minimum 250 cfm. Lennox Smart Zoning System Applications - Minimum blower speed is 250 cfm. - Page 41 First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan Only speed is selectable at 28% and 38% of the selected second stage cooling speed - minimum 450 cfm. Lennox Smart Zoning System Applications - Minimum blower speed is 450 cfm.
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Page 42: Low Gwp Application
Low GWP Application WARNING For use with Lennox approved evaporator coil and LGWP sensors only. Use original manufacturer recommended LGWP sensors if using non Lennox approved evaporator coil. CONNECTING THE FURNACE CONTROL BOARD SENSOR. See FIGURE 32 and follow steps below: 1 - Route sensor wire #1 through provided grommet. - Page 43 FURNACE CONTROL BOARD LOW GWP MODES OF 2. The furnace control board activates the blower (high OPERATION speed). The blower purges refrigerant from the cabinet, plenum, and ductwork. The modes of operation for the furnace control board are Initializing, Normal, Leak Detected, and Fault. 3.
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Page 44: Heating Demand
LGWP TEST BUTTON FUNCTIONALITY External Alarm (For applications with external alarms wired directly to the The furnace control board is equipped with a Test/Reset furnace control board) push button. The Test button can be used to perform sev- The furnace control board triggers the external alarm sys- eral functions, depending on the mode of operation of the tem when it enters Leak Detected mode. -
Page 45: Unit Start-Up
6 - Move gas valve switch to OFF position. Do not force. Unit Start-Up See FIGURE 33. WARNING 7 - Wait five minutes to clear out any gas. If you then smell gas, STOP! Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s Do not use this furnace if any part has been underwater. -
Page 46: Proper Combustion
TABLE 24 Supply Line Pressure A port on the inlet side of the gas valve provides access to GAS METER CLOCKING CHART the supply pressure tap. Loosen the screws and connect Seconds for One Revolution a manometer to measure supply pressure. The minimum SL280NVK Natural LP Propane... -
Page 47: Other Unit Adjustments
Applications Using Two-Stage Thermostat Other Unit Adjustments See FIGURE 34 for ignition control sequence Primary Limits A - Heating Sequence Integrated Control Thermostat Selection DIP Switch 1 OFF in “Two-Stage”Position The primary limit is located on the heating compartment (Factory Setting) vestibule panel. - Page 48 Applications Using Single-Stage Thermostat 4 - After the 20-second warm-up period has ended, the See FIGURE 35 for ignition control sequence gas valve is energized on low fire (first stage) and ignition occurs. At the same time, the control module B - Heating Sequence -- Integrated Control Thermostat sends a signal to begin an indoor blower 30-second Selection DIP Switch 1 ON in “Single-Stage”...
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Page 49: Service
Perform a general system test. Turn on the furnace to At the beginning of each heating season, and to comply check operating functions such as the start-up and shut- with the Lennox Limited Warranty, your system should be off operation. checked by a licensed professional technician (or equiva-... -
Page 50: Burner Removal
Cleaning the Burner 4 - To clean burner and intake debris screen, run a vacuum cleaner over the face of burners. Visually NOTE - Use papers or protective covering in front of the inspect inside the burner. Remove any blockage. furnace during cleaning. -
Page 51: Repair Parts List
Repair Parts List The following repair parts are available through independent Lennox dealers. When ordering parts, include the complete furnace model number listed on the CSA International nameplate -- Example: SL280UH060NV36AK-01. All service must be performed by a licensed professional installer (or equivalent), service agency, or gas supplier. -
Page 52: Program Unit Capacity Size / Code
Program Unit Capacity / Size Code − − Power-Up - Number displayed represents by integrated control unit size code (furnace model − and capacity). If three horizontal bars are displayed followed by continuous E203, furnace control does not recognize unit size code. Configure per the following: Furnace control in IDLE mode No heating, cooling or indoor fan operation) -
Page 53: Troubleshooting
Troubleshooting: Heating Sequence of Operation CALL FOR FIRST-STAGE HEAT CALL FOR 1ST STAGE HEAT (LOW FIRE) INDOOR BLOWER OFF AFTER HEAT FAN OFF DELAY (LOW HEAT SPEED) INDOOR LIMIT BLOWER OFF HIGH ERROR INDOOR SWITCH WATCHGUARD − AFTER HEAT FAN LIMIT SWITCH CODE BLOWER... - Page 54 Troubleshooting: Heating Sequence of Operation (Continued) CALL FOR SECOND-STAGE HEAT CALL FOR 2ND STAGE HEAT (HIGH FIRE) SINGLE STAGE 2 STAGE THERMOSTAT THERMOSTAT 2ND STAGE RECOGNITION DELAY ON DELAY (30 SECONDS) EXPIRED? EXPIRED? ONLY FOR 1ST REQUEST FOR 2ND STAGE HEAT INDUCER SWITCHED TO HIGH SPEED HIGH...
- Page 55 Troubleshooting: Heating Sequence of Operation (Continued) CALL FOR HEAT SATISFIED FIRST-STAGE HEAT SECOND-STAGE HEAT RUN MODE: 1ST OR 2ND STAGE CALL FOR HEAT. ALL INPUTS MONITORED (LIMIT, PRESSURE, CALL FOR HEAT/COOL, FLAME LEVEL) 2ND STAGE HEAT 2ND STAGE CALL FOR HEAT SATISFIED? DE−ENERGIZE 2ND STAGE GAS VALVE...
- Page 56 Troubleshooting: Cooling Sequence of Operation CALL FOR COOLING 1ST STAGE COOLING REQUEST RECEIVED WAIT FOR COMPRESSOR TIMED OFF DELAY TO EXPIRE ENERGIZE 1ST STAGE COOLING CONTACTOR (COMPRESSOR & FAN) INDOOR BLOWER 2 SECOND ON DELAY ENERGIZE INDOOR BLOWER (LOW COOLING MODE) MAINTAIN INDOOR BLOWER (LOW COOLING MODE)
- Page 57 Troubleshooting: Fan Sequence of Operation CALL FOR FAN CALL FOR FAN INDOOR BLOWER ON CONTINUOUS FAN SPEED CALL FOR FAN MAINTAIN INDOOR BLOWER AT REMOVED? CONTINUOUS FAN REQUEST MAINTAIN INDOOR FOR COOLING GO TO CALL FOR COOLING BLOWER AT RECEIVED? CONTINUOUS FAN REQUEST INDOOR BLOWER OFF...
- Page 58 Allowable Heating Speeds SL280 -18% -12% Default +12% +18% +24% Model 060NV36A Factory Setting 080NV48B Factory Setting Allowed Allowed Allowed Allowed Allowed Allowed Allowed 080NV60C Factory Setting 100NV60C Factory Setting Not Allowed Allowable Circulation Speeds Model Number (second stage cool (second stage cool) All Models Allowed...
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