1. Manuals
  2. Brands
  3. Lennox Manuals
  4. Furnace
  5. A98USMV
  6. Installation instructions manual

Lennox A98USMV Installation Instructions Manual

Warm air gas furnace upflow/horizontal left/right air discharge direct vent
Hide thumbs
Table of Contents

Advertisement

Quick Links

Download this manual
INSTALLATION INSTRUCTIONS
A98USMV
This is a safety alert symbol and should never be ignored. When you see this symbol on labels or in manuals, 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 installer (or
equivalent), service agency or the gas supplier.
NOTICE
A thermostat is not included and must be ordered
separately.
•
A Comfort Sync
®
communicating applications.
•
In non-communicating applications, a traditional
non-communication thermostat may be used.
In all cases, setup is critical to ensure proper system
operation.
Field wiring for both communicating and non-
communicating applications is illustrated in these
instructions.
Manufactured By
Allied Air Enterprises LLC
A Lennox International, Inc. Company
215 Metropolitan Drive
West Columbia, SC 29170
508364-01
This manual must be left with the homeowner for future reference.
WARNING
thermostat must be used in
Warm Air Gas Furnace
Upflow/Horizontal Left/Right
Air Discharge Direct Vent

Table of Contents

Gas Furnace ................................................................4
Shipping and Packing List ...........................................4
Safety Information .......................................................4
General ........................................................................6
Installation ...................................................................6
Filters .........................................................................10
Duct System ..............................................................10
Venting Practices .......................................................12
Gas Piping .................................................................27
Electrical ....................................................................30
Blower Performance ..................................................45
Gas Valve Operation .................................................50
Unit Start-Up ..............................................................50
Other Unit Adjustments..............................................54
Heating Sequence of Operation ................................55
Service.......................................................................56
Integrated Control Diagnostic Codes.........................58
Repair Parts List ........................................................65
As with any mechanical equipment, personal injury can
result from contact with sharp sheet metal edges. Be
careful when you handle this equipment.
*P508364-01*
Issue 2346
CAUTION
(P) 508364-01
Page 1 of 74

Advertisement

Table of Contents
loading

Related Manuals for Lennox A98USMV

Summary of Contents for Lennox A98USMV

  • Page 1: Table Of Contents

    Be instructions. careful when you handle this equipment. Manufactured By *P508364-01* Allied Air Enterprises LLC A Lennox International, Inc. Company 215 Metropolitan Drive (P) 508364-01 West Columbia, SC 29170 508364-01 Issue 2346...
  • Page 2 Unit Dimensions EXHAUST AIR 3-1/4 OUTLET (83) 1-7/8 (48) Flue Condensate Trap Assembly Furnished for external SUPPLY AIR OPENING field installation (178) on either side of unit. (See installation instructions COMBUSTION for additional AIR INTAKE information.) OPTIONAL 23-3/4 SIDE RETURN (603) AIR FILTER KIT (Either Side)
  • Page 3 Parts Arrangement BURNER BOX ASSEMBLY PRESSURE SWITCHES HEAT EXCHANGER VARIABLE CAPACITY PRIMARY LIMIT GAS VALVE VARIABLE SPEED COMBUSTION AIR INDUCER BAG ASSEMBLIES (shipping location) COLD END HEADER ACCESS PANEL VARIABLE SPEED BLOWER MOTOR SHIPPING BLOCK (-135 UNITS ONLY) CONTROL BOX (includes variable capacity integrated control transformer, circuit breaker and door switch) Figure 1.

  • Page 4: Gas Furnace

    A change over kit must be ordered for difficult to smell. An LP/Propane leak detector should be LP/propane applications. installed in all LP applications. The A98USMV must be installed only as a Direct Vent gas central furnace WARNING NOTE: In Direct Vent installations, combustion air is taken from outdoors and flue gases are discharged outdoors.
  • Page 5 National Fuel Gas Code or CSA B149 standards. must not exceed 85°F (29°C) dry bulb. NOTE: Furnace must be adjusted to obtain a temperature The A98USMV furnace may be installed in alcoves, rise (100% percent capacity) within the range(s) specified closets, attics, basements, garages, crawl spaces and on the unit nameplate.

  • Page 6: General

    All furnace operating conditions (including ignition, NOTE: The Commonwealth of Massachusetts stipulates input rate, temperature rise and venting) must these additional requirements: be verified in accordance with these installation • Gas furnaces shall be installed by a licensed plumber instructions. or fitter only.
  • Page 7 Figure 4. Left Side Right Side A98USMV applications that include side return air and a condensate trap installed on the same side of the cabinet (trap can be installed remotely within 5 feet) require either a return air base or field fabricated transition to accommodate an optional IAQ accessory taller than 14.5”.
  • Page 8 removed before the furnace is placed into operation. After the bolt and washer have been removed, the rigid leg will not touch the blower housing. 20” X 25” X 1” (508mm X 635mm X 25mm) Air Filter Return Plenum Transition Figure 6.
  • Page 9 Figure 10. damage and to allow the evaporator coil to drain. The A98USMV furnace can be installed in horizontal applications with either right or left hand air discharge. Refer to Figure 11 for clearances in horizontal applications.

  • Page 10: Filters

    Supply Air Plenum If the furnace is installed without a cooling coil, a removable access panel should be installed in the supply air duct. The access panel should be large enough to permit inspection (by reflected light) of the heat exchanger for leaks after the furnace is installed.
  • Page 11 Use PVC primer and solvent cement or ABS solvent Piping and Fittings Specifications cement meeting ASTM specifications, refer to Table 2. As an alternate, use all purpose cement, to bond ABS, Schedule 40 PVC (Pipe) D1785 PVC, or CPVC pipe when using fittings and pipe made of Schedule 40 PVC (Fittings) D2466 the same materials.

  • Page 12: Venting Practices

    during assembly (but not after pipe is fully inserted) to distribute cement evenly. DO NOT turn ABS or cellular CAUTION core pipe. Do not discharge exhaust into an existing stack or NOTE: Assembly should be completed within 20 stack that also serves another gas appliance. If vertical seconds after last application of cement.
  • Page 13 STANDARD CONCENTRIC Outdoor Outdoor Exhaust Exhaust Flush Mount 1-1/2" 2" Concentric 3" Concentric VENT Accelerator Accelerator Concentric Kit Capacity PIPE DIA. (Dia. X Length) (Dia. X Length) (in.) 71M80 69M29 60L46 1-1/2" x12" 2" x12" 51W11** +44W92++ +44W92++ 44W93+ 1-1/2 2-1/2"...
  • Page 14 Use the steps in Figure 16 to correctly size vent pipe NFPA 54 in U.S.A., and current CSA-B149 Natural Gas diameter. and Propane Installation Codes in Canada for details. Position termination according to location given in Figure 20. In addition, position termination so it is free from any obstructions and 12”...
  • Page 15 TYPICAL EXHAUST AND INTAKE PIPE CONNECTIONS IN UPFLOW 2” EXHAUST EXHAUST INTAKE INTAKE 2” 2” 2” 2” 2” 3” 3” 070 Only 1−1/2” TRANSITION Exhaust 2” 6” Min Exhaust DO NOT transition from larger to smaller DO NOT transition pipe in horizontal runs from smaller to larger Exhaust of exhaust pipe.
  • Page 16 Maximum Allowable Exhaust Vent Pipe Length (in ft.) without Insulation in Unconditioned Space For Winter Design Temperatures Single - Stage High Efficiency Furnace Unit Input Size Winter Design Temperatures Vent Pipe ºF (ºC) Diameter 1-1/2 in. 32 to 21 2 in. (0 to -6) 2-1/2 in.
  • Page 17 Maximum Allowable Intake or Exhaust Vent Length (feet) Standard Termination at Elevation 0 - 4,500 ft 1-1/2” Pipe 2” Pipe 2-1/2” Pipe 3” Pipe Number of Model Model Model Model 90° Elbows Used Standard Termination at Elevation 4,501 - 10,000 ft 1-1/2”...
  • Page 18 Maximum Allowable Intake or Exhaust Vent Length (feet) Concentric Termination at Elevation 0 - 4,500 ft 1-1/2” Pipe 2” Pipe 2-1/2” Pipe 3” Pipe Number of Model Model Model Model 90° Elbows Used Concentric Termination at Elevation 4,501 - 10,000 ft 1-1/2”...
  • Page 19 VENT TERMINATION CLEARANCES FOR DIRECT VENT INSTALLATIONS IN THE USA AND CANADA INSIDE CORNER DETAIL Fixed Operable Fixed Closed Closed Operable AREA WHERE TERMINAL AIR SUPPLY INLET VENT TERMINAL IS NOT PERMITTED US Installations Canadian Installations Clearance above grade, veranda, 12 inches (305mm) or 12 inches (305mm) 12 inches (305mm) or 12 inches (305mm) porch, deck or balcony...
  • Page 20 FIELD FABRICATED WALL TERMINATION NOTE − FIELD−PROVIDED REDUCER MAY BE 2” (51mm) 3” (76mm) REQUIRED TO ADAPT LARGER VENT PIPE SIZE Vent Pipe Vent Pipe TO TERMINATION A− Minimum clearance above grade or average 12” (305 mm) 12” (305 mm) snow accumulation B−...
  • Page 21 Details of Intake and Exhaust Piping Terminations for Direct Vent Installations NOTE: In Direct Vent installations, combustion air is taken from outdoors and flue gases are discharged to outdoors. NOTE: Flue gas may be slightly acidic and may adversely affect some building materials. If any vent termination is used and the flue gasses may impinge on the building Inlet Air material, a corrosion resistant shield (minimum 24 inches...
  • Page 22 If intake and exhaust piping must be run up a side FIELD-PROVIDED 1-1/2” (38mm) accelerator wall to position above snow accumulation or other REDUCER MAY BE REQUIRED provided on 71M80 & 44W92 TO ADAPT DIFFERENT VENT kits for -045 and -070 models obstructions, piping must be supported every 24”...
  • Page 23 Exhaust through Crawl Space Vent Option All 33” condensing gas furnaces (92%+) are now approved Exhaust from Furnace to be vented down through a crawl space. Ensure a vent To Termination pipe drain kit, 51W18 (USA) or 15Z70 (Canada), is used as directed through the floor joists and into the crawl space.
  • Page 24 Condensate Piping line were to become restricted. This unit is designed for either right or left side exit of Horizontal furnace (Figure 36 or Figure 39) - In condensate piping in upflow applications. In horizontal horizontal furnace applications, the field provided vent applications, the condensate trap must extend below the must be a minimum 4”...
  • Page 25 Optional Condensate Drain Connection Adapter 3/4 inch slip X 3/4 inch mpt (not furnished) 90° Elbow 3/4 inch PVC (not furnished) Adapter 3/4 inch slip X 3/4 inch mpt (not furnished) Condensate Drain Connection In Unit 1 (25 mm) Min. Vent 2 (50 mm) Max.
  • Page 26 (Unit shown in horizontal left-hand discharge position) Field Provided Vent Evaporator (4” min. to 5” max. above Coil condensate drain connection) 4”min 5”max 5’ max. PVC Pipe Only Condensate Drain Connection (Trap at coil is optional) Drain Pan Piping from furnace and evaporator coil must slope down a minimum 1/4” per ft. toward trap Figure 36.

  • Page 27: Gas Piping

    When connecting gas supply, factors such as length of run, number of fittings and furnace rating must be IMPORTANT considered to avoid excessive pressure drop. Table 8 lists recommended pipe sizes for typical applications. When combining the furnace and evaporator coil drains together, the A/C condensate drain outlet must NOTE: Use two wrenches when connecting gas piping be vented to relieve pressure in order for the furnace...
  • Page 28 Gas Pipe Capacity - FT³/HR (kL/HR) Nominal Length or Pipe - feet (m) Internal Iron Pipe Diameter Size - - inches inches (3.048) (6.096) (9.144) (12.192) (15.240) (18.288) (21.336) (24.384) (27.432) (30.480) (mm) (mm) .622 (12.7) (17.799) (4.96) (3.40) (2.75) (2.32) (2.07) (1.87)
  • Page 29 IMPORTANT WARNING When testing pressure of gas lines, gas valve must be FIRE OR EXPLOSION HAZARD disconnected and isolated. See Figure 41. Gas valves Failure to follow the safety warnings exactly could can be damaged if subjected to pressures greater than result in serious injury, death, or property damage.

  • Page 30: Electrical

    Resize the common venting system to the minimum vent pipe size determined by using the appropriate tables in WARNING the current standards of the National Fuel Gas Code ANSI Z223.1. CARBON MONOXIDE POISONING HAZARD Failure to follow the steps outlined below for each Electrical appliance connected to the venting system being placed into operation could result in carbon monoxide...
  • Page 31 The unit is equipped with a field makeup box. The makeup terminals. See Figure 56 for location of terminal. This box may be moved to the right side of the furnace to terminal is energized in the heating mode when the facilitate installation.
  • Page 32 When there is a cooling demand, the indoor blower will the unit is varied to maximize comfort. Conventional two run on the cooling speed designated by the positions stage mode is the factory default setting. See Table 12. of DIP switches 8 through 11. Switch 3 - Second Stage Heat On Delay - If a single stage thermostat is used, the integrated control can be Generator Use - Voltage Requirements...
  • Page 33 • Once demand is met, motor runs at 50% for 30 Speed Switch 8 Switch 9 seconds then ramps down to stop. 1 - Low 2 - Medium Low 3 - Medium High 4 - High (factory) Table 13. Cooling Mode Blower Speeds Ramping Option “B”...
  • Page 34 Error Code Recall Mode - Select “E” from the menu to Blower DIP Switch Settings Thermostat access the most recent 10 error codes. Select “c” from the Speed Demand Error Code Recall menu to clear all error codes. Button Adjustments must be pressed a second time while “c”...
  • Page 35 BLACK WHITE BLACK WHITE GN/YLW WHITE WHITE WHT/ PINK FLAME SENSOR FLAME SENSE BLACK CIRC WHITE BLACK 120V YELLOW BLUE BLUE RO(OUT) BROWN BROWN RO(IN) BLUE BLUE S102 PURPLE (HI) PINK S128 (LO) PINK YELLOW ORANGE AUTO Figure 46. Typical Field Wiring Diagram for Standard Non-Communicating Thermostat 508364-01 Issue 2346 Page 35 of 74...
  • Page 36 DATS (Optional) OATS (Optional) Communicating Communicating Outdoor Unit Indoor Unit Smart Hub Display Subbase Figure 47. Comfort Sync A3 with Communicating Indoor and Outdoor Units DATS (Optional) OATS (Optional) SETUP NOTES: CUT Y1-Y2 ON-BOARD MUNICATING) CUT R-O ON-BOARD LINK FOR OUTDOOR HEAT MUNICATING) Smart Hub Display...
  • Page 37 DATS (Optional) OATS (Optional) SETUP NOTE: CUT Y1-Y2 ON-BOARD LINK FOR 2-STAGE OUTDOOR UNITS (NON-COMMUNICATING) Smart Hub Display Subbase 24VAC Outdoor Unit Communicating (1 - or 2-Stage Indoor Unit Air Conditioner) Figure 49. Comfort Sync A3, Communicating Indoor Unit with 24VAC Air Conditioner Communicating Outdoor Unit If jumber is present between...
  • Page 38 Indoor Unit Controller Outdoor Unit Smart Hub HD Display Subbase 12VDC COM BUS ACC1 ACC2 R i+ I- C +12V -12V Single wire Single wire to indoor unit to bundle terminal “C”. wire to indoor Single wire terminal “C”. to terminal “C”. Unused wires Unused wires Unused wires...
  • Page 39 24VAC UV Light Applications: In any Allied communicating system, the indoor unit will FURNACE (IFC) OR AIR HANDLER (AHC) NOT have adequate power to to run the 24VAC UV light application. An additional transformer will be required. UV light wiring connections are independent of the HVAC system operation CHARGE AIR SENSOR (refer to UV light installation instruction.
  • Page 40 Communicating Indoor Unit HRV/ERV Terminal Block Smart Hub Display Subbase Wire Jumper required between ON and RED terminals. ACC1 is always low-stage for single- and two-stage ventilators. Figure 55. Comfort Sync A3 with Ventilation (Fresh Air Damper, ERV and HRV) Page 40 of 74 Issue 2346 508364-01...
  • Page 41 NEUTRAL TERMINALS COMBUSTION AIR INDUCER CONNECTOR IGNITOR CONNECTOR FLAME SENSE DIAGNOSTIC LINE VOLTAGE PUSH BUTTON TERMINALS DIP SWITCHES INDOOR BLOWER CONNECTOR OUTDOOR AIR SENSOR TERMINALS 7-SEGMENT DIAGNOSTIC LED W915 Y1 TO Y2 DISCHARGE AIR SENSOR W951 R TO O TERMINALS W914 R TO DS FACTORY TEST W915...
  • Page 42 DIP Switch Settings and On-Board Links W915 W914 W951 Thermostat Wiring Connections (Y1 to Y2) DIP Switch 1 (DS to R) (Oto R) Two-Stage Dehumidification Heat Pumps Cooling FURNACE OUTDOOR T'STAT TERM. STRIP UNIT 1 Heat / 1 Cool NOTE: Use DIP switch 3 to set Intact...
  • Page 43 DIP Switch Settings and On-Board Links W915 W914 W951 Thermostat Wiring Connections (Y1 to Y2) DIP Switch 1 (DS to R) (Oto R) Two-Stage Dehumidification Heat Pumps Cooling FURNACE OUTDOOR T'STAT TERM. STRIP UNIT 2 Heat / 2 Cool Intact Intact *Not required on all units FURNACE...
  • Page 44 DIP Switch Settings and On-Board Links W915 W914 W951 Thermostat Wiring Connections (Y1 to Y2) DIP Switch 1 (DS to R) (Oto R) Two-Stage Dehumidification Heat Pumps Cooling FURNACE HEAT PUMP TERM. STRIP T'STAT Dual Fuel Single- Stage Heat Pump Thermostat w/dual Intact Intact...

  • Page 45: Blower Performance

    Blower Performance A98USMV070B12S BLOWER PERFORMANCE (less filter) HEATING BLOWER PERFORMANCE Heating Input Range and Blower Volume - CFM Heating Adjust CFM Selections 100% Increase (+15%) Heat CFM 1030 1128 Increase (+7.5%) Heat CFM 1048 Default Heat CFM Decrease (-7.5% ) Heat CFM Decrease (-15% ) Heat CFM COOLING BLOWER PERFORMANCE Blower Speed Selections...
  • Page 46 A98USMV090C16S BLOWER PERFORMANCE (less filter) HEATING BLOWER PERFORMANCE Heating Input Range and Blower Volume - CFM Heating Adjust CFM Selections 100% Increase (+15%) Heat CFM 1101 1234 1367 1500 1633 Increase (+7.5%) Heat CFM 1028 1155 1281 1407 1534 Default Heat CFM 1075 1195 1314...
  • Page 47 A98USMV110C20S BLOWER PERFORMANCE (less filter) HEATING BLOWER PERFORMANCE Heating Input Range and Blower Volume - CFM Heating Adjust CFM Selections 100% Increase (+15%) Heat CFM 1049 1237 1424 1612 1800 1988 Increase (+7.5%) Heat CFM 1000 1174 1349 1524 1699 1874 Default Heat CFM 1112...
  • Page 48 • With Heat Pump - Cut W914 (R to DS) and W951 (R to O) on integrated control setpoint is 2°F. Table 21. Cooling Operating Sequence A98USMV and Single Stage Outdoor Unit Page 48 of 74 Issue 2346 508364-01...
  • Page 49 • With Heat Pump - Cut W914 (R to DS) and W951 (R to O) on integrated control setpoint is 2°F. Table 22. Cooling Operating Sequence A98USMV and Two Stage Outdoor Unit 508364-01 Issue 2346 Page 49 of 74...

  • Page 50: Gas Valve Operation

    Wait for the combustion air inducer to stop. Set the Unit Start-Up thermostat to initiate a heating demand and again allow the burners to fire for approximately 3 minutes. FOR YOUR SAFETY READ BEFORE OPERATING Adjust the thermostat to deactivate the heating demand and again wait for the combustion air inducer to stop.
  • Page 51 Gas Pressure Measurement NEGATIVE AIR POSITIVE AIR PRESSURE PORT PRESSURE PORT Gas Flow (Approximate) Seconds for One Revolution Natural Capacity 1 cu ft 2 cu ft 1 cu ft 2 cu ft OUTLET Dial Dial Dial Dial INLET -070 -090 -110 SUPPLY MANIFOLD...
  • Page 52 After allowing unit to stabilize for 5 minutes, record High Altitude Information manifold pressure and compare to value given in NOTE: In Canada, certification for installation at elevations Table 26. over 4500 feet (1372 m) is the jurisdiction of local Repeat steps 3, 4 and 5 on HIGH HEAT.
  • Page 53 Gas Valve Field Installed Figure 58. Manifold Pressure Measurement Negative Port Positive Port Red and Black Tubing - Black Tubing + Gas Valve Field Installed Measuring Device Figure 59. Operation Signal (Delta P) Measurement 508364-01 Issue 2346 Page 53 of 74...

  • Page 54: Other Unit Adjustments

    Exhaust and Air Intake Pipe Other Unit Adjustments Check exhaust and air intake connections for tightness and to make sure there is not blockage. Primary Limit Are pressure switches closed? Obstructed exhaust The primary limit is located on the heating compartment pipe will cause unit to shut off at pressure switches.

  • Page 55: Heating Sequence Of Operation

    target rate. Heating Sequence of Operation When the demand for high fire (second stage) heat is satisfied, the gas valve is de-energized and the The integrated control initiates a pressure switch field selected indoor blower off delay begins. The calibration at the initial unit start-up on a call for heat. The combustion air inducer begins a 20 second post purge ignition control will also initiate a calibration any time main period.

  • Page 56: Service

    the present firing rate until the heat cycle ends. Service When the demand for first and second stage heat is satisfied, the gas valve is de-energized and the field selected indoor blower OFF delay begins. The WARNING combustion air inducer begins a 20 second post-purge period.
  • Page 57 Winterizing and Condensate Trap Care 17. Remove two screws from the front cabinet flange at the blower deck. Spread cabinet sides slightly to allow Turn off power to the unit. clearance for removal of heat exchanger. Have a shallow pan ready to empty condensate water. 18.

  • Page 58: Integrated Control Diagnostic Codes

    Planned Service 38. Reinstall burner box cover. A service technician should check the following items 39. Reconnect 2 pin plug to gas valve. during an annual inspection. Power to the unit must be 40. Replace the blower compartment access panel. shut off for the service technician’s safety.
  • Page 59 Code Diagnostic Codes / Status of Equipment Action Required to Clear and Recover Idle mode (Decimal blinks at 1 Hertz - 0.5 seconds ON, 0.5 seconds OFF). Cubic feet per minute (cfm) setting for indoor blower (1 second ON, 0.5 seconds OFF) / cfm setting for current mode displayed.
  • Page 60 Code Diagnostic Codes / Status of Equipment Action Required to Clear and Recover E125 Control failed self-check, internal error, failed Hardware problem on the control. Cycle power on hardware. Will restart if error recovers, Integrated control. Replace if problem prevents service and is control not communicating Covers hardware errors persistent.
  • Page 61 Code Diagnostic Codes / Status of Equipment Action Required to Clear and Recover E207 Hot surface igniter sensed open - Refer to Measure resistance of hot surface igniter. Replace if troubleshooting open or not within specified range found in installation/ operation manual.
  • Page 62 Code Diagnostic Codes / Status of Equipment Action Required to Clear and Recover E271 Soft lockout - Exceeded maximum number of Check pressure (inches w.c.) of low pressure switch retries. Last retry failed due to the pressure switch closing on heat call. Measure operating pressure opening.
  • Page 63 Code Diagnostic Codes / Status of Equipment Action Required to Clear and Recover E311 Heat rate reduced to match indoor blower airflow. Warning Only. Furnace blower in cutback mode due to restricted airflow. Reduce firing rate every 60 seconds to match available CFM. Check filter and duct system. To clear replace filter if needed or repair/add duct.
  • Page 64 Code Diagnostic Codes / Status of Equipment Action Required to Clear and Recover E407 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.

  • Page 65: Repair Parts List

    Repair Parts List The following repair parts are available through Allied Air distributors. When ordering parts, include the complete furnace model number listed on the nameplate. All service must be performed by a licensed professional installer (or equivalent), service agency, or gas supplier. Cabinet Parts Heating Parts •...
  • Page 66 Program Unit Capacity / Size Mode Power-Up - Number displayed by integrated control represents 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: Turn room thermostat to OFF.
  • Page 67 Troubleshooting: Heating Sequence of Operation IGNITION AND CALL FOR LOW FIRE WITH TWO-STAGE THERMOSTAT Safety Check Verify There Is No Main Burner Flame After Indoor blower OFF Heat OFF Delay (Low Heat Speed) Limit Combustion Air Limit Indoor Blower De-Energize Error Code Inducer On Switch...
  • Page 68 Troubleshooting: Heating Sequence of Operation (continued) CALL FOR HIGH FIRE WITH TWO-STAGE THERMOSTAT 2 Stage Thermostat 1st Call for High Fire? 2nd Stage Recognition Delay (30 Seconds) Combustion Air Inducer ON (100% Rate Speed) High Pressure Switch Increase Combustion Error Code Wait 5 Closes Within Air Inducer Speed...
  • Page 69 Troubleshooting: Heating Sequence of Operation (continued) RUN MODE (TWO-STAGE THERMOSTAT) RUN MODE (SINGLE-STAGE THERMOSTAT) FIRST OR SECOND-STAGE CALL FOR HEAT ALL INPUTS MONITORED (LIMIT, PRESSURE, ALL INPUTS MONITORED (LIMIT, PRESSURE, CALL FOR HEAT/COOL, FLAME LEVEL). CALL FOR HEAT/COOL, FLAME LEVEL). 2nd Stage Heat 2nd Stage Call for Heat...
  • Page 70 Troubleshooting: Heating Sequence of Operation (continued) IGNITION AND CALL FOR HEAT WITH SINGLE-STAGE THERMOSTAT Safety Check Verify There Is No Main Burner Indoor Blower OFF After Flame Heat OFF Delay (Low Heat Speed) Indoor Blower Limit Limit De-Energize Combustion Air Error Code Switch Closes Within 3...
  • Page 71 Troubleshooting: Cooling Sequence of Operation CALL FOR COOLING 1st Stage Cooling Request Received Energize 1st Stage Cooling Contactor (Compressor & Fan) Indoor Blower On After 2-second delay Energize Indoor Blower (Per Ramping Profile) 1st Stage 2nd Stage Cooling Request Cooling Still Active? Request? Energize 2nd Stage...
  • Page 72 Troubleshooting: Continuous Fan Sequence of Operation CONTINUOUS LOW SPEED INDOOR BLOWER SEQUENCE OF OPERATION Call for Continuous Blower Indoor Blower On (Speed Determined by Dip Switch settings) Request Maintain Indoor for Cooling Go to Call for Cooling Blower at set speed Received? Go to Call for Heat -- Two-Stage Thermostat Request...
  • Page 73 Requirements for Commonwealth of Massachusetts Modifications to NFPA-54, Chapter 10 INSPECTION. The state or local gas inspector of the side wall, horizontally vented, gas-fueled equipment Revise NFPA-54 section 10.8.3 to add the following shall not approve the installation unless, upon requirements: inspection, the inspector observes carbon monoxide For all side wall, horizontally vented, gas-fueled equipment...
  • Page 74 For the Province of Ontario, Horizontal Sidewall Vent Applications Only For exterior horizontal venting applications, the 2” X 1.5” reducer for 2” venting at the point where the exhaust pipe exits the structure is not required in direct or nondirect vent applications in the Province of Ontario. In these applications, the vent should be oriented such that the exhaust plume is unobjectionable.

Table of Contents