INSTALLATION INSTRUCTIONS SL280DFV 2011 Lennox Industries Inc. Dallas, Texas, USA DAVE LENNOX SIGNATURE® COLLECTION GAS FURNACE DOWNFLOW AIR DISCHARGE 506710−01 06/2011 Supersedes 01/2011 Litho U.S.A. THIS MANUAL MUST BE LEFT WITH THE HOMEOWNER FOR FUTURE REFERENCE WARNING Improper installation, adjustment, alteration, service or maintenance can cause property damage, personal injury or loss of life.
Unit Dimensions − inches (mm) 3−1/8 (79) 9/16 (14) D RETURN AIR OPENING B FLUE OUTLET (Top) 19−7/16 (494) 9/16 (14) 9/16 (14) TOP VIEW A 9/16 (14) B 33 (838) 27−3/4 (7705) 1−1/2 (38) Front Panel 19−7/16 (494) 9/16 (14) ELECTRICAL INLET (Either Side) 5−3/8 (137) Right 2−1/8 (54) Left GAS PIPING INLET (Either Side) 6−5/8 (168) Right 7−1/8 (181) Left C Supply Air 19−1/4 Supply (489) Air 3/4 (19) FRONT VIEW Model No.
Parts Arrangement BLOWER ASSEMBLY GASKET SECONDARY LIMIT FLUE CHASE CONTROL BOX (Includes two−stage integrated control, transformer and circuit breaker) INTERNAL FLUE PIPE ASSEMBLY DOOR INTERLOCK SWITCH PRIMARY LIMIT LOCATION ROLLOUT SWITCH HEAT EXCHANGER COMBUSTION AIR INDUCER PRESSURE SWITCHES COMBUSTION AIR INDUCER GAS VALVE INNER BLOWER ACCESS PANEL BURNER BOX ASSEMBLY ACCESS PANEL FIGURE 1 Page 3
SL280DFV Gas Furnace CAUTION The SL280DFV gas furnace is equipped with a two−stage, variable speed integrated control. the control is compatible with: Communicating thermostats − icomfort Touch®. Non−communicating thermostats − ComfortSense or other conventional thermostats. Control systems − Harmony III Zone Control System (non−communicating). Each SL280DFV unit is shipped ready for installation in the downflow position.
chilled air from entering the furnace (see figure 1). If the damper is manually operated, it must be equipped to prevent operation of either the heating or the cooling unit, unless it is in the full HEAT or COOL setting. AIR HANDLER GAS UNIT Dampers Dampers (open during cooling operation only) (open during heating operation only) FIGURE 1 When installed, this furnace must be electrically grounded according to local codes.
D The gas cock must be T handle" type. D When a furnace is installed in an attic, the passageway to and service area surrounding the equipment shall be floored. CAUTION Insufficient combustion air can cause headaches, nausea, dizziness or asphyxiation. It will also cause excess water in the heat exchanger resulting in rusting and premature heat exchanger failure. Excessive exposure to contaminated combustion air will result in safety and performance related problems.
Confined Space A confined space is an area with a volume less than 50 cubic feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of the combined input rating of all appliances installed in that space. This definition includes furnace closets or small equipment rooms.
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 AIR FURNACE WATER HEATER INLET AIR VENTILATION LOUVERS (For unheated crawl space) NOTE−The inlet and outlet air openings shall each have a free area of at least one square inch (645 mm2) per 4,000 Btu (1.17 kW) per hour of the total input rating of all equipment in the enclosure.
Downflow Installation CAUTION Downflow unit installs in three ways: on non−combustible flooring, on combustible flooring using a downflow combustible flooring base, or on a reverse−flow cooling cabinet. Do not drag the unit across the floor. The furnace and downflow combustible flooring base shall not be installed directly on carpeting, tile, or other combustible material other than wood flooring.
Setting Equipment SL280DFV UNIT WARNING Do not install the furnace on its front, back or in the horizontal position. See figure 12. Do not connect the return air ducts to the back of the furnace. Doing so will adversely affect the operation of the safety control devices, which could result in personal injury or death. COOLING COIL PROPERLY SIZED FLOOR OPENING PLENUM Install the SL280DFV gas furnace as shipped in the downflow position only. Do not install the furnace horizontally.
Front Horizontal Back FIGURE 12 Downflow Application Allow for clearances to combustible materials as indicated on the unit nameplate. Minimum clearances for closet or alcove installations are shown in figure 13. Downflow Application Installation Clearances Top Left Side Right Side Bottom WARNING Improper installation of the furnace can result in personal injury or death. Combustion and flue products must never be allowed to enter the return air system or the living space.
Duct System Use industry-approved standards (such as those published by Air Conditioning Contractors of America or American Society of Heating, Refrigerating and Air Conditioning Engineers) to size and install the supply and return air duct system. This will result in a quiet and low-static system that has uniform air distribution. NOTE − Do not operate the furnace in the heating mode with an external static pressure that exceeds 0.8 inches w.c.
Common Venting Using Tile−Lined Interior Masonry Chimney and Combined Vent Connector NOTE− Refer to provided venting tables for installations. MINIMUM LENGTH = AS SHORT AS PRACTICAL. FOR MAXIMUM LENGTH SEE NOTE TO LEFT INTERIOR TILE−LINED MASONRY CHIMNEY NOTE − the chimney must be properly sized per provided venting tables or lined with listed metal lining system.
TABLE 4 Never connect a Category I appliance to a chimney that is servicing a solid−fuel appliance. If a fireplace chimney flue is used to vent this appliance, the fireplace opening must be permanently sealed. A type B or listed chimney lining system that passes through an unused masonry chimney flue is not considered to be exposed to the outdoors.
21 − When connecting this appliance to an existing dedi18 − The common vent diameter must always be at least as large as the largest vent connector diameter. cated or common venting system, you must inspect the 19 − In no case, shall the vent connector be sized more than venting system’s general condition and look for signs two consecutive table size diameters over the size of of corrosion. The existing vent pipe size must conform the draft hood outlet or flue collar outlet.
TABLE 6 Capacity of Type B Double−Wall Vents with Single−Wall Metal Connectors Serving a Single Category I Appliance Vent and Connector Diameter − D (inches) Height H (feet) 6 8 10 15 20 30 Lateral L (feet) 3 Inch 4 Inch 5 Inch 6 Inch Appliance Input Rating in Thousands of Btu Per Hour MIN MAX MIN MAX MIN MAX MIN MAX 0 38 77 59 151 85 249 126 373 2 39 51 60 96 85 156 123 231 4 NR NR 74 92 102 152 146 225 6 NR NR 83 89 114 147 163 220 0 37 83 58 164
TABLE 7 Vent Connector Capacity Type B Double−Wall Vents with Type B Double−Wall Connectors Serving Two or More Category I Appliances Vent Height H (feet) 6 8 10 15 20 30 Vent and Connector Diameter − D (inches) Connector Rise R (feet) 3 Inch 4 Inch 5 Inch 6 Inch Appliance Input Rating in Thousands of Btu Per Hour MIN MAX MIN MAX MIN MAX MIN MAX 1 22 37 35 66 46 106 58 164 2 23 41 37 75 48 121 60 183 3 24 44 38 81 49 132 62 199 1 22 40 35 72 49 114 64
TABLE 9 Vent Connector Capacity Type B Double−Wall Vents with Single−Wall Metal Connectors Serving Two or More Category I Appliances Vent and Connector Diameter − D (inches) Height H (feet) 6 8 10 15 20 30 Lateral L (feet) 3 Inch 4 Inch 5 Inch 6 Inch Appliance Input Rating in Thousands of Btu Per Hour MIN MAX MIN MAX MIN MAX MIN 1 NR NR NR NR NR NR NR MAX NR 2 NR NR NR NR NR NR 168 182 3 NR NR NR NR 121 131 175 198 1 NR NR NR NR NR NA NR NR 2 NR NR N
Removal of the Furnace from Common Vent In the event that an existing furnace is removed from a venting system commonly run with separate gas appliances, the venting system is likely to be too large to properly vent the remaining attached appliances. Conduct the following test while each appliance is operating and the other appliances (which are not operating) remain connected to the common venting system.
TABLE 11 Gas Pipe Capacity − ft3/hr (m3/hr) Nominal Iron Pipe Size inches (mm) Internal Diameter inches (mm) 10 (3.048) 20 (6.096) 30 (9.144) 40 (12.192) 50 (15.240) 60 (18.288) 70 (21.336) 80 (24.384) 90 (27.432) 100 (30.480) 1/2 (12.7) .622 (17.799) 175 (4.96) 120 (3.40) 97 (2.75) 82 (2.32) 73 (2.07) 66 (1.87) 61 (1.73) 57 (1.61) 53 (1.50) 50 (1.42) 3/4 (19.05) .824 (20.930) 360 (10.19) 250 (7.08) 200 (5.66) 170 (4.81) 151 (4.28) 138 (3.91) 125 (3.54) 118 (3.34) 110 (3.
Leak Check After gas piping is completed, carefully check all piping connections (factory− and field−installed) for gas leaks. Use a leak detecting solution or other preferred means. NOTE − If emergency shutoff is necessary, shut off the main manual gas valve and disconnect the main power to the furnace. The installer should properly label these devices. Refer to figure 24 for unit field wiring. See figures 21 and 22 for icomfort Touch® thermostat wiring in communicating applications.
2 − Holes are on both sides of the furnace cabinet to facilitate wiring. 3 − Install a separate (properly sized) disconnect switch near the furnace so that power can be turned off for servicing. 4 − Before connecting the thermostat or the power wiring, check to make sure the wires will be long enough for servicing at a later date. Remove the blower access panel to check the length of the wire. 5 − Complete the wiring connections to the equipment.
Generator Use − Voltage Requirements The following requirements must be kept in mind when specifying a generator for use with this equipment: The furnace requires 120 volts (Range: 102 volts to 132 volts) The furnace operates at 60 Hz + 5% (Range: 57 Hz to 63 Hz) icomfort Touch® Thermostat with SL280DFV and Non−Communicating Outdoor Unit The furnace integrated control requires both correct polarity and proper ground.
Optional Accessories for use with any icomfort Touch® System NOTE: icomfort Touch® THERMOSTAT SENSES HUMIDITY & CONTROLS HUM CONTACTS TO CYCLE HUMIDIFIER BASED ON DEMAND. NO OTHER CONTROL OR HUMIDISTAT REQUIRED. 120V CONNECTIONS HUM" CONTACT IS CLOSED ANYTIME HUMIDITY DEMAND IS PRESENT OPTIONAL OUTDOOR AIR SENSOR FOR USE WITH HUMIDIFIER (IF NOT ALREADY IN THE SYSTEM FOR OTHER FUNCTIONS. BUILT INTO ALL icomfort by Lennox OUTDOOR UNITS).
TABLE 13 SL280 Field Wiring Applications With Conventional Thermostat DIP Switch Settings and On−Board Links (See figure 25) Thermostat DIP Switch 1 Thermostat Heating Stages 1 Heat / 1 Cool NOTE − Use DIP switch 2 to set second−stage heat ON delay. OFF−7 minutes. ON−12 minutes. ON 1 Heat / 2 Cool NOTE − Use DIP switch 2 to set second−stage heat ON delay. OFF−7 minutes. ON−12 minutes. ON 1 Heat / 2 Cool with t’stat with humidity control NOTE − Use DIP switch 2 to set second−stage heat ON delay.
TABLE 13 SL280 Field Wiring Applications With Conventional Thermostat (Continued) DIP Switch Settings and On−Board Links (See figure 25) Thermostat DIP Switch 1 Thermostat Heating Stages 2 Heat / 2 Cool On Board Links Must Be Cut To Select System Options OFF Wiring Connections S1 T’STAT CUT ON−BOARD LINK W915 2 STAGE COMPR FURNACE TERM. STRIP OUTDOOR UNIT * 2 Heat / 2 Cool with t’stat with humidity control OFF S1 T’STAT CUT ON−BOARD LINK W915 2 STAGE COMPR FURNACE OUTDOOR TERM.
TABLE 13 SL280 Field Wiring Applications With Conventional Thermostat (Continued) Thermostat Dual Fuel Single Stage Heat Pump DIP Switch Settings and On−Board Links (figure 25) DIP Switch 1 On Board Links Must Be Cut To Select Thermostat System Options Heating Stages L7724U T’STAT OFF CUT ON−BOARD LINK W951 HEAT PUMP ComfortSense 7000 L7724U thermostat w/ dual fuel capabilities Capable of 2 stage gas heat control Wiring Connections FURNACE TERM.
TABLE 13 SL280 Field Wiring Applications With Conventional Thermostat (Continued) Thermostat Dual Fuel Single Stage Heat Pump DIP Switch Settings and On−Board Links (figure 25) DIP Switch 1 On Board Links Must Be Cut To Select Thermostat System Options Heating Stages L7724U T’STAT OFF ComfortSense 7000 L7724U thermostat w/ dual fuel capabilities Capable of 2 stage gas heat control w/dehumidification control Wiring Connections CUT ON−BOARD LINK W951 HEAT PUMP H CUT ON−BOARD LINK W914 DEHUM OR HARMON
SL280DFV Schematic Wiring Diagram FIGURE 23 Page 29
TYPICAL SL280DFV FIELD WIRING DIAGRAM FIELD INSTALLED CLASS II 24V FIELD INSTALLED LINE VOLTAGE FIGURE 24 Page 30
Integrated Control ACC HUM HS/ CAI LINE 1 NEUTRAL 7 SEGMENT LED FLAME SENSE INDOOR BLOWER CONNECTOR DIAGNOSTIC PUSH BUTTON DIP SWITCHES 12 PIN LOW VOLTAGE CONNECTOR OUTDOOR AIR SENSOR TERMINALS DISCHARGE AIR SENSOR TERMINALS W915 Y1 TO Y2 2 STAGE COMPR W951 R TO O HEAT PUMP TB83 COMMUNICATING OUTDOOR EQUIPMENT TB84 COMMUNICATING INDOOR THERMOSTAT R I+ I−C R I+ I−C W1 W2 G Y2 Y1 C C R DH L O DS W914 R TO DS DEHUM OR HARMONY NON−COMMUNICATINGNG 24V TERMINALS RS−BUS LINK (TB82, future use) THER
Integrated Control DIP Switch Settings − Conventional Thermostat (non−communicating) SL280DFV units are equipped with a two−stage, variable speed integrated control. This control manages ignition timing, heating mode fan off delays and indoor blower speeds based on selections made using the control dip switches and jumpers. The control includes an internal watchguard feature which automatically resets the ignition control when it has been locked out.
NOTE − The off portion of the selected ramp profile also applies during heat pump operation in dual fuel applications. TABLE 17 Cooling Mode Blower Speed Ramping Switch 9 Switch 10 Ramping Option A (Factory) Off Off B Off On C On Off D On On Ramping Option A (Factory Selection) Motor runs at 50% for 30 seconds. Motor then runs at 82% for approximately 7−1/2 minutes. If demand has not been satisfied after 7−1/2 minutes, motor runs at 100% until demand is satisfied.
On−Board Links Note: In icomfortt systems with a conventional outdoor unit (non−communicating), the on−board clippable links must be set to properly configure the system WARNING Carefully review all configuration information provided. Failure to properly set DIP switches, jumpers and on−board links can result in improper operation! On−Board Link W914 Dehum or Harmony (R to DS) On−board link W914, is a clippable connection between terminals R and DS on the integrated control.
BLOWER DATA SL280DF070V36A BLOWER PERFORMANCE (less filter) 0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g.
BLOWER DATA SL280DF090V60C BLOWER PERFORMANCE (less filter) 0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g.
TABLE 20 SL280DFV, Non−Communicating Thermostat with Humidity Control Feature and Single−Speed Outdoor Unit OPERATING SEQUENCE SYSTEM DEMAND Thermostat Demand System Condition Step Y1 O G W 1 SYSTEM RESPONSE Relative Humidity Compressor Blower CFM (COOL) Status D Acceptable 24 VAC High 100% Comments NO CALL FOR DEHUMIDIFICATION Normal Operation 1 On On On Compressor and indoor blower follow thermostat demand BASIC MODE (only active on a Y1 thermostat demand) Normal Operation 1 On
TABLE 21 SL280DFV, Non−Communicating Thermostat with Humidity Control Feature and Two−Speed Outdoor Unit OPERATING SEQUENCE SYSTEM DEMAND Thermostat Demand System Condition Step Y1 Y2 O G On On W 1 SYSTEM RESPONSE Relative Humidity W 2 Compressor Blower CFM (COOL) Status D On Acceptable 24 VAC Low 70%* On Acceptable 24 VAC High 100% Comments NO CALL FOR DEHUMIDIFICATION Normal Operation − Y1 1 On Normal Operation − Y2 2 On On Compressor and indoor blower follow thermostat d
Unit Start−Up FOR YOUR SAFETY READ BEFORE LIGHTING WARNING Do not use this furnace if any part has been underwater. Immediately call a licensed professional service technician (or equivalent) to inspect the furnace and to replace any part of the control system and any gas control which has been under water. WARNING If overheating occurs or if gas supply fails to shut off, shut off the manual gas valve to the appliance before shutting off electrical supply.
TABLE 22 GAS METER CLOCKING CHART Seconds for One Revolution Natural LP SL280 Unit 1 cu ft 2 cu ft 1 cu ft 2 cu ft Dial Dial Dial DIAL −045 80 160 200 400 −70 55 110 136 272 −90 41 82 102 204 −110 33 66 82 164 −135 27 54 68 136 12− If the appliance will not operate, follow the instructions Turning Off Gas to Unit" and call your service technician or gas supplier. Turning Off Gas to Unit 1 − Set the thermostat to the lowest setting.
High Altitude The manifold pressure, gas orifice and pressure switch may require adjustment or replacement to ensure proper operation at higher altitudes. Tables 24 through 27 shows manifold pressure, pressures switch and gas conversion kits at all altitudes. IMPORTANT For safety, shut unit off and remove manometer as soon as an accurate reading has been obtained. Take care to replace pressure tap plug. TABLE 24 Manifold Pressure Settings Unit Input 070 090 110 1 This Orifice Size 0 − 7500 ft.
Other Unit Adjustments Primary and Secondary Limits The primary limit is located on the heating compartment vestibule panel. The secondary limits (if equipped) are located in the blower compartment, attached to the back side of the blower. These limits are factory set and require no adjustment. Flame Rollout Switch This manually reset switch is located on the burner box. If tripped, check for adequate combustion air before resetting.
4 − After the 20−second warm−up period has ended, the gas valve is energized on low fire (first stage) and ignition occurs. At the same time, the control module sends a signal to begin an indoor blower 30−second ON−delay. When the delay ends, the indoor blower motor is energized on the low fire heating speed and the HUM contacts are energized. The integrated control also initiates a second−stage on delay (factory−set at 7 minutes; adjustable to 12 minutes).
Electrical Service 1 − Check all wiring for loose connections. 2 − Check for the correct voltage at the furnace (furnace operating). Correct voltage is 120VAC + 10%. WARNING ELECTRICAL SHOCK, FIRE, OR EXPLOSION HAZARD. Failure to follow safety warnings exactly could result in dangerous operation, serious injury, death or property damage. Improper servicing could result in dangerous operation, serious injury, death, or property damage. Before servicing, disconnect all electrical power to furnace.
SL280DFV BURNER, COMBUSTION AIR INDUCER ASSEMBLY & HEAT EXCHANGER REMOVAL gasket orifice plate gasket flue chase internal flue pipe combustion air inducer rollout switch ignitor burner box assembly collector box pressure switch heat exchanger sensor gasket burners manifold and gas valve retention rings burner box cover plate cross over FIGURE 30 Page 45
12− To clean the combustion air inducer visually inspect and using a wire brush clean where necessary. Use compressed air to clean off debris and any rust. 22− Repeat steps 21 and 23 until no leaks are detected. 23− Replace access panel. 13− Reinstall heat exchanger in vestibule. (Replace the five screws in the cabinet from step 10 if removed). 14− Reinstall collector box, combustion air assembly, internal flue pipe and flue chase. Seal with high temperature RTV.
Planned Service The following items should be checked during an annual inspection. Power to the unit must be shut off for the service technician’s safety. Fresh air grilles and louvers (on the unit and in the room where the furnace is installed) − Must be open and unobstructed to provide combustion air. Operating performance − Unit must be observed during operation to monitor proper performance of the unit and the vent system. Burners − Must be inspected for rust, dirt, or signs of water.
Integrated Control Diagnostic Modes Display Action (when button released) No change (idle)* Remain in idle mode Solid E" Enter diagnostic recall mode Solid D" Discharge Air Installed Solid F" Enter flame signal mode Solid P" (variable speed only) Program unit capacity/size (Unit Code)** * No change implies the display will continue to show whatever is currently being displayed for normal operation (blinking decimal, active error code, heat state, etc..
Integrated Control Diagnostic Codes (continued) Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover E 105 Device communication problem − No other devices on RS BUS (Communication system). Equipment is unable to communicate. Indicates numerous message errors. In most cases errors are related to electrical noise. Make sure high voltage power is separated from RSBus. Check for mis− wired and/or loose connections between the stat, indoor unit and outdoor unit.
Integrated Control Diagnostic Codes (continued) E 131 Corrupted control parameters (Verify configuration of system). Communicating only. Reconfigure the system. Replace control if heating or cooling is not available. Only applicable in the communicating mode, not in startup. Exit from Commissioning and Execute ’Set Factory Default mode’. Control will still operate on default parameter settings. E 180 Outdoor air temperature sensor failure. Only shown if shorted or out−of− range.
Integrated Control Diagnostic Codes (continued) Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover E 223 Low pressure switch failed open. Check pressure (inches w.c.) of low pressure switch closing on heat call. Measure operating pressure (inches w.c.). Inspect vent and combustion air inducer for correct operation and restriction. Resumes normal operation after fault is cleared E 224 Low pressure switch failed closed − Refer to troubleshooting. See Page 56.
Integrated Control Diagnostic Codes (continued) E 272 Soft lockout − Exceeded maximum number of recycles. Last recycle due to the pressure switch opening. Check operation of low pressure switch to see if it is stuck closed on heat call. Check pressure (inches w.c.) of high pressure switch closing on heat call. Measure operating pressure (inches w.c.). Inspect vent and combustion air inducer for correct operation and restriction. Clears when heat call finishes successfully.
Integrated Control Diagnostic Codes (continued) Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover E 312 Restricted air flow in cooling or continuous fan mode is lower than cfm setting. Warning Only. Restricted airflow − Indoor blower is running at a reduced CFM (Cutback Mode − The variable speed motor has pre−set speed and torque limiters to protect the motor from damage caused by operating outside of design parameters (0 to 0.8" W.C.. total external static pressure).
Integrated Control Diagnostic Codes (continued) E 406 LSOM − Compressor open start circuit. Required amount of current is not passing through Start current transformer. Clears the error after current is sensed in START sensor, or after power reset. E 407 LSOM − Compressor open run circuit. Required amount of current is not passing through Run current transformer. Clears the error after current is sensed in RUN sensor, or 1 normal compressor run cycle, or after power reset.
Program Unit Capacity/Size Mode 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) Yes To enter Program Unit Capacity/Size: push and hold button next to 7−segment LED display until solid P" symbol appears. Release button.
Troubleshooting: Heating Sequence of Operation CALL FOR FIRST−STAGE HEAT 1 CALL FOR 1ST STAGE HEAT (LOW FIRE) NO INDOOR BLOWER OFF AFTER HEAT FAN OFF DELAY (LOW HEAT SPEED) HIGH LIMIT SWITCH CLOSED? NO ERROR CODE FLASHES YES LIMIT SWITCH CLOSED WITHIN 3 MINUTES? INDOOR BLOWER ON(LOW HEAT SPEED) NO INDOOR BLOWER OFF AFTER HEAT FAN OFF DELAY (LOW HEAT SPEED) WATCHGUARD − ERROR CODE 1 FLASHES NO YES ROLLOUT CIRCUITS CLOSED? NO DE−ENERGIZE GAS VALVE YES LOW PRESSURE SWITCH OPEN? NO INDUCER ON
Troubleshooting: Heating Sequence of Operation (Continued) CALL FOR SECOND−STAGE HEAT 2 CALL FOR 2ND STAGE HEAT 1 (HIGH FIRE) SINGLE STAGE THERMOSTAT 2 2 STAGE THERMOSTAT 2ND STAGE ON DELAY EXPIRED? RECOGNITION DELAY (30 SECONDS) EXPIRED? ONLY FOR 1ST REQUEST FOR 2ND STAGE HEAT YES YES INDUCER SWITCHED TO HIGH SPEED HIGH PRESSURE SWITCH CLOSED WITHIN 10 SECONDS? NO INDUCER SWITCHED TO LOW SPEED 5 MINUTE DELAY (ERROR CODE FLASHES) 3 YES 2ND STAGE GAS VALVE ENERGIZED INDOOR BLOWER ENERGIZED ON
Troubleshooting: Heating Sequence of Operation (Continued) CALL FOR HEAT SATISFIED FIRST−STAGE HEAT SECOND−STAGE HEAT 2 3 RUN MODE: 1ST OR 2ND STAGE CALL FOR HEAT.
Troubleshooting: Cooling Sequence of Operation (Continued) CALL FOR COOLING 1 1ST STAGE COOLING REQUEST RECEIVED 1 WAIT FOR COMPRESSOR TIMED OFF DELAY TO EXPIRE ENERGIZE 1ST STAGE COOLING CONTACTOR (COMPRESSOR & FAN) INDOOR BLOWER 2 SECOND ON DELAY ENERGIZE INDOOR BLOWER 2 (LOW COOLING MODE) MAINTAIN INDOOR BLOWER (LOW COOLING MODE) 1 2ND STAGE COOLING REQUEST? YES ENERGIZE 2ND STAGE COOLING CONTACTOR (COMPRESSOR & FAN) YES YES 1ST STAGE COOLING REQUEST STILL ACTIVE? NO YES ENERGIZE INDOOR BLOWER 2 (H
Troubleshooting: Continuous Fan Sequence of Operation CALL FOR FAN 1 CALL FOR FAN INDOOR BLOWER ON CONTINUOUS FAN SPEED NO CALL FOR FAN REMOVED? MAINTAIN INDOOR BLOWER AT CONTINUOUS FAN YES REQUEST FOR COOLING RECEIVED? YES MAINTAIN INDOOR BLOWER AT CONTINUOUS FAN 4 GO TO CALL FOR COOLING INDOOR BLOWER OFF 1 GO TO CALL FOR 1ST STAGE HEAT NO REQUEST FOR HEAT RECEIVED? YES NO DE−ENERGIZE INDOOR BLOWER 1 Page 60
