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S e r v i c e L i t e r a t u r e
ML296DFVK(X) series units are 90% efficiency gas fur-
naces used for downflow applications only, manufactured
with Lennox Duralok heat exchangers formed of alumi-
nized steel. ML296DFVK(X) units are available in heating
capacities of 44,000 to 88,000 Btuh and cooling appli-
cations up to 5 tons. Refer to Engineering Handbook for
proper sizing.
Units are factory equipped for use with natural gas. Kits
are available for conversion to LPG operation. ML296D-
FVK(X) unit meets the California Nitrogen Oxides (NOx)
Standards and California Seasonal Efficiency require-
ments. All units use a redundant gas valve to assure safe-
ty shut-off as required by C.S.A.
All specifications in this manual are subject to change.
Procedures outlined in this manual are presented as a
recommendation only and do not supersede or replace lo-
cal or state codes. In the absence of local or state codes,
the guidelines and procedures outlined in this manual (ex-
cept where noted) are recommendations only and do not
constitute code.
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
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 2
Blower Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 4
I Unit Components . . . . . . . . . . . . . . . . . . . . . . . . Page 7
II Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 21
III Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 43
VI Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . Page 47
VII Low GWP Application. . . . . .. . . . . . . . . . . . . . . . Page 50
VIII- Diagram and DIP Switch Settings. . . . . .. . . . .Page 53
UNIT INFORMATION
UNIT INFORMATION
ML296DFVK(X) With R-454B SERIES UNITS
the
refrigerant
detection
100178
Improper
installation,
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.
As with any mechanical equipment, contact with
sharp sheet metal edges can result in personal
injury. Take care while handling this equipment and
wear gloves and protective clothing.
ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
Electrostatic discharge can affect electronic
components. Take precautions to neutralize
electrostatic charge by touching your hand
and tools to metal prior to handling the
control.
Page 1
ML296DFVK(X)
C C C C
I I I I
HI
HI
WARNING
adjustment,
CAUTION
CAUTION
.
alteration,
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Related Manuals for Lennox ML296DFVK Series
Summary of Contents for Lennox ML296DFVK Series
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Page 1: Table Of Contents
ML296DFVK(X) series units are 90% efficiency gas fur- naces used for downflow applications only, manufactured with Lennox Duralok heat exchangers formed of alumi- nized steel. ML296DFVK(X) units are available in heating capacities of 44,000 to 88,000 Btuh and cooling appli- cations up to 5 tons. -
Page 2: Specifications
SP ECIF ICATIONS Model ML296DF045XV36BK ML296DF070XV48BK ML296DF090XV60CK Heating AHRI Reference No. 202575917 202575918 202575919 Performance AFUE High Input - Btuh 44,000 66,000 88,000 Fire Output - Btuh 43,000 64,000 85,000 Temperature rise range - °F 35-65 35-65 40-70 Gas Manifold Pressure (in. w.g.) 3.5 / 10.0 3.5 / 10.0 3.5 / 10.0... -
Page 3: Optional Accessories
OP TIONA L AC C ESSORIES NOTE - FURNACES CANNOT BE TWINNED! “B” Width Models “C” Width Models CABINET ACCESSORIES Downflow Combustible Flooring Base 11M60 11M61 CONDENSATE DRAIN KITS Condensate Drain Heat Cable 6 ft. 26K68 26K68 26K69 26K69 24 ft. Crawl Space Vent Drain Kit 51W18 51W18... -
Page 4: Blower 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 approximately 38% of the same second stage COOL speed position. Lennox Harmony III™ Zoning System Applications - Minimum blower speed is 300 cfm. B LO WER DATA... - Page 5 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 approximately 38% of the same second stage COOL speed position. Lennox Harmony III™ Zoning System Applications - Minimum blower speed is 460 cfm. Page 5...
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Page 6: Parts Identification
PARTS IDENTIFICATION CONTROL BOX (Includes integrated control, transformer and door switch) VARIABLE SPEED MOTOR (hidden) 16X4W Box (some models) BAG ASSEMBLY (shipping location) COMBUSTION AIR INDUCER BLOWER DECK DuralokPlus HEAT EXCHANGER ASSEMBLY ACCESS PANEL COLD END HEADER BOX COMBUSTION AIR INDUCER PRESSURE SWITCH PRIMARY LIMIT BURNER BOX ASSEMBLY... -
Page 7: I Unit Components
I-UNIT COMPONENTS 3. Integrated Control (A92) ML296DFVK(X) unit components are shown in FIGURE 1. Units are equipped with a two-stage, variable speed inte- The gas valve, combustion air inducer and burners can be grated control. The system consists of a ignition / blower accessed by removing the access panel. - Page 8 Two Stage, Variable Speed, Non-Communicating 107629-XX FIGURE 3 Page 8...
- Page 9 TABLE 4 Low GWP Test Page 9...
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Page 10: Integrated Control
Integrated Control Switch Settings Bank Of Eight DIP Switches SW2 Conventional Thermostat Switches 1 and 2 - Cooling Mode Blower Speed - The unit is shipped from the factory with the dip switches po- ML296DFVK units are equipped with a two-stage, vari- sitioned for high speed (4) indoor blower motor operation able speed integrated control. - Page 11 TABLE 9 Heat Speed DIP Switch 7 DIP Switch 8 Medium High (Default) High Medium Low TABLE 10 Allowable Heating Speeds ML296DFVK Speed Adjust Setting “D” Setting “C” Setting “B” Setting “A” Model +10% Allowed 045XV36BK Norm Factory Setting Allowed -10% Allowed +10%...
- Page 12 ON BOARD LINKS Accessory Terminals One line voltage “ACC” 1/4” spade terminal is provided on WARNING the furnace integrated control. Refer to FIGURE 53 for integrated control configuration. This terminal is energized Carefully review all configuration information provided. when the indoor blower is operatingAny accessory rated Failure to properly set DIP switches, jumpers and on- up to one amp can be connected to this terminal with the board links can result in improper operation!
- Page 13 B-Indoor Blower GenTeq BLOWER MOTOR B3 MOTOR CONTROLLER FIGURE 5 NIDEC BLOWER MOTOR B3 MOTOR 16X4 Pin Wire Box (May be located Power Choke Blower Motor on the blower (5 Ton Only) housing) (B3) To Remove Blower From Unit: Remove Bolts and Wiring Jackplugs.
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Page 14: Motor Start-Up
TABLE 11 Nidec Motor Only PW LED RX LED TX LED Motor Blower Action Blink Blink Not Rotating Normal Blink Blink Blink Rotating Normal. PW blink is 100cfm/blink Verify 16X4W and motor control hp match. Verify power to motor control. Blink Blink Not Rotating... - Page 15 2. Power Choke (L13) GenTeq HARNESS CONNECTORS A choke coil is used on 5 ton 1 hp units. The choke is POWER CONTROL CONNECTOR J48 CONNECTOR J49 located on the blower housing and is used to suppress transient current spikes. PIN 1 C1 PIN 2 W / W1 Precautions...
- Page 16 Inlet and outlet pressure taps are located on the valve. A regulator adjustment screw is located on the valve LPG change over kits are available from Lennox. Kits in- clude burner orifices and a gas valve. Page 16...
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Page 17: Heating Components
HEATING COMPONENTS Burner Assembly Intake Air Top Cap Sensor Rollout Switch Rollout Switch Ignitor Manifold And Gas Orifices Burner Box Cover Two-Stage Gas Valve FIGURE 10 Page 17... - Page 18 Ignitor Check Test 1 Check ignitor circuit for correct resistance. Remove HSI/CAI 5-pin plug from control. Check ohms reading across terminals 1 and 5. Reading should be between 39 and 70 ohms. If value is correct, this is the only test needed. If the reading on the meter is not correct, (0 or infinity) then a second test is needed.
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Page 19: Combustion Air Pressure Switch
NOTE - Each furnace model uses a unique CAI. Refer to and gas valve. A bleed port on the switch allows relatively Lennox Repair Parts listing for correct inducer for replace- dry air in the vestibule to purge switch tubing, to prevent ment. -
Page 20: Pressure Switch Check
Pressure Switch Check 5 - Operate unit and observe manometer reading. Readings will change as heat exchanger warms. To check pressure switch differential, refer to and use the a. Take one reading immediately after start-up. provided fittings and tubing to follow the steps below. b. -
Page 21: Ii-Placement And Installation
II-PLACEMENT AND INSTALLATION TABLE 9 Continued CANADA PIPE & FITTING & SOLVENT Pipe & Fittings Specifications MARKING CEMENT All pipe, fittings, primer and solvent cement must conform PVC & CPVC Pipe and Fittings with American National Standard Institute and the Ameri- can Society for Testing and Materials (ANSI/ASTM) stan- PVC &... - Page 22 1 - Remove inner blower door. Top Vent Configuration Exhaust/Air 2 - Loosen hose clamps which attach rubber fittings to Intake Connections the white PVC pipes inside the vestibule area. See FIGURE 14. 3 - Loosen the clamp which secures the pipes at the blower deck.
- Page 23 Right Side Vent Configuration Side Vent Sealing Plate Side Vent Sealing Gaskets Exhaust Intake Street Elbows (2) FIGURE 16 Page 23...
- Page 24 TABLE 16 OUTDOOR TERMINATION USAGE* STANDARD CONCENTRIC Flush Mount Wall Kit 1-1/2 inch 2 inch 3 inch Vent Pipe Dia. Input Size Field 2 inch 3 inch Fabricated 51W11 (US) 71M80 (US) 69M29 (US) 60L46 (US) 22G44 (US) 44J40 (US) 51W12 (CA) 444W92 (CA) 444W92 (CA)
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Page 25: Danger Of Explosion
Joint Cementing Procedure Venting Practices All cementing of joints should be done according to the NOTE - For any Low GWP refrigerant systems with ex- specifications outlined in ASTM D 2855. posed line set joints installed in the same space, each non-direct vent furnace system must have a refrigerant NOTE - A sheet metal screw may be used to secure the detection sensor installed below the level of the burners... - Page 26 4 - Follow the lighting instructions. Turn on the appliance REPLACING FURNACE THAT WAS PART OF A that is being inspected. Adjust the thermostat so COMMON VENT SYSTEM that the appliance operates continuously. CHIMNEY 5 - After the main burner has operated for 5 minutes, OR GAS VENT test for leaks of flue gases at the draft hood relief...
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Page 27: Vent Piping Guidelines
NOTE - Exhaust pipe MUST be glued to furnace exhaust Vent Piping Guidelines fittings. NOTE - Lennox has approved the use of DuraVent® and NOTE - Exhaust piping should be checked carefully to Centrotherm manufactured vent pipe and terminations make sure there are no sags or low spots. - Page 28 TABLE 18 Maximum Allowable Intake or Exhaust Vent Length Size intake and exhaust pipe length separately. Values in table are for Intake OR Exhaust, not combined total. Both Intake and Exhaust must be same pipe size. NOTE - Additional vent pipe and elbows used to terminate the vent pipe outside the structure must be included in the total vent length calcu- lation.
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Page 29: Top View
TYPICAL EXHAUST PIPE CONNECTIONS 045/070 Only 2” 1−1/2” 2” 2” 2” TRANSITION 2” 2” Exhaust Exhaust 3” DO NOT transition from larger to smaller pipe in horizontal runs of exhaust pipe. TRANSITION INTAKE EXHAUST DO NOT transition from smaller *2” to larger pipe size in horizontal TOP VIEW runs of exhaust pipe. - Page 30 TYPICAL EXHAUST CONNECTIONS WITH RIGHT SIDE VENT OPTION Pipe Length 4” Maximum (Not Furnished) 3” 2” 2” TRANSITION *2” 2” Plate (Furnished) Street Ell (Not Furnished) TOP VIEW * When transitioning up in pipe size, use the shortest length of 2” PVC pipe possible. NOTE Intake pipe and exhaust pipe must be the same diameter.
- Page 31 Intake Piping EQUIPMENT IN CONFINED SPACE (Inlet Air from Ventilated Crawlspace and Outlet Air to Outside) The ML296DFVK furnace may be installed in either direct vent or non-direct vent applications. In non-direct vent applications, when intake air will be drawn into the furnace Roof Terminated Exhaust Pipe from the surrounding space, the indoor air quality must be...
- Page 32 In Direct Vent applications, combustion air is taken from TYPICAL AIR INTAKE PIPE CONNECTIONS outdoors and the flue gases are discharged to the out- NON−DIRECT VENT APPLICATIONS doors. The ML296DFVK is then classified as a direct vent, Category IV gas furnace. INTAKE In both Non-Direct Vent and Direct Vent applications, the SCREEN...
- Page 33 TABLE 19 Maximum Allowable Exhaust Vent Pipe Length (in ft. ) Without Insulation In Unconditioned Space For Winter Design Temperatures Two - Stage High Efficiency Furnace Winter Design Unit Input Size Vent Pipe Tempera- Diameter tures1 °F (°C) 1-1/2 32 to 21 2 in (0 to -6) 2-1/2 in...
- Page 34 TABLE 20 Maximum Allowable Exhaust Vent Length Using Ventilated Attic or Crawl Space For Intake Air in Feet NOTE - Additional vent pipe and elbows used to terminate the vent pipe outside the structure must be included in the total vent length calculation. Standard Termination at Elevation 0 - 10,000 ft Number 1-1/2...
- Page 35 ‡ Permitted only if veranda, porch, deck or balcony is fully open NOTE - This figure is intended to illustrate clearance on a minimum of two sides beneath the floor. Lennox recommends requirement and does not serve as a substitute for avoiding this location if possible.
- Page 36 ‡ Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two sides beneath the floor. Lennox recommends avoiding this location if possible. locally adopted installation codes.
- Page 37 Details of Intake and Exhaust Piping Terminations for one bracket must be used within 6” from the top of Direct Vent Installations the elbow and then every 24” (610mm) as shown in FIGURE 33, to prevent any movement in any NOTE - In Direct Vent installations, combustion air is taken direction.
- Page 38 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 39 2” EXTENSION FOR 2” PVC Accelerator not required for PIPE1” EXTENSION FOR 3” 3” concentric PVC PIPE FURNACE EXHAUST PIPE FLASHING 12” (305mm) (Not Furnished) INTAKE Minimum FURNACE Above Average INTAKE Snow PIPE Accumulation GLUE EXHAUST END FLUSH INTO TERMINATION SHEET METAL STRAP (Clamp and sheet metal strap FLAT...
- Page 40 3 - If exhaust piping must be run up a side wall CONDENSATE TRAP AND PLUG LOCATIONS to position above snow accumulation or other obstructions, piping must be supported every 24 inches (610mm). When exhaust piping must be run up an outside wall, any reduction in exhaust pipe size must be done after the final elbow.
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Page 41: Start Up
Heat CAUTION cable kit is available from Lennox in various lengths; 6 ft. (1.8m) - kit no. 26K68; 24 ft. (7.3m) - kit no. Do not use copper tubing or existing copper condensate 26K69;... - Page 42 TRAP / DRAIN ASSEMBLY USING 1/2” PVC OR 3/4” PVC Optional Condensate Drain Connection Adapter 3/4 inch slip X 3/4 inch mpt (not furnished) 90° Street 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.
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Page 43: Iii-Start-Up
III-START-UP 4 - This furnace is equipped with an ignition device which automatically lights the burners. Do not try to A-Preliminary and Seasonal Checks light the burners by hand. 1 - Inspect electrical wiring, both field and factory 5 - Remove the upper access panel. installed for loose connections. -
Page 44: Heating System Service Checks
IV-HEATING SYSTEM SERVICE CHECKS It is available through Lennox under part number 31B2001. See Corp. 8411-L10, for further details. A-CSA Certification Do not use matches, candles, flame or any other All units are CSA design certified without modifications. source of ignition to check for gas leaks. - Page 45 NOTE- To obtain accurate reading, shut off all other gas G- Proper Combustion appliances connected to meter. Furnace should operate minimum 15 minutes with correct TABLE 22 manifold pressure and gas flow rate before checking com- bustion. See sections E- and F-. Take combustion sam- GAS METER CLOCKING CHART ple beyond the flue outlet.
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Page 46: Furnace Status
I- Proper Ground and Voltage 2 - In addition, measure the AC voltage from Line Hot to Line Neutral (spade terminals) on the integrated A poorly grounded furnace can contribute to premature control. See FIGURE 49. This voltage should be in ignitor failure. -
Page 47: Typical Operating Characteristics
V-TYPICAL OPERATING CHARACTERISTICS 3 - With only the blower motor running and the evaporator coil dry, observe the manometer A-Blower Operation and Adjustment reading. Adjust blower motor speed to deliver the 1 - Blower operation is dependent on thermostat control air desired according to the job requirements. - Page 48 1 - Turn off electrical and gas supplies to the furnace. specifications provided by the filter manufacturer against 2 - Remove the furnace access panels. the data given in the appropriate Lennox Product 3 - Disconnect the wires from the gas valve. Specifications bulletin. Additional information is provided in Service and Application Note ACC002 (August 2000).
- Page 49 14 - Disconnect condensate line from cold end header 38 - Reinstall gas valve manifold assembly. Reconnect box. Remove cold end header box. gas supply line to gas valve. 15 - Loosen clamps on exhaust and air intake pipe seal 39 - Reinstall burner box cover if equipped.
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Page 50: Low Gwp Application
TABLE 28 WARNING DIP Switch Settings Configuration Switch 1 Switch 2 For use with Lennox approved evaporator coil and LGWP One (1) sensor, connected to SEN- sensors only. Use original manufacturer recommended SOR 1 plug (enable) (disable) LGWP sensors if using non Lennox approved evaporator Two (2) sensors, connected to SEN- coil. - Page 51 TABLE 29 lists the functions of the Test button during each Leak Detected When the furnace control board detects a refrigerant leak: mode of operation. 1. The furnace control board shuts off the (R) input TABLE 29 (24VAC power) to the thermostat, which de- LGWP Test Button Function energizes the outdoor unit compressor and heat Mode of Operation...
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Page 52: Start-Up Procedure
Cooling Demand External Alarm (For applications with external alarms wired directly to the 1. Prompt a cooling demand at the thermostat. furnace control board) 2. Press the LGWP Test button on the furnace control The furnace control board triggers the external alarm sys- board. -
Page 53: Viii- Diagram And Dip Switch Settings
VIII- Unit Diagram, Sequence of Operation and DIP Switch Settings Page 53... - Page 54 Sequence of Operation WARNING Heating The system must not be in either the passive or active On a call for heat from the room thermostat, the control dehumidification mode when charging a cooling system. board performs a 1 second self check. Upon confirma- tion that the pressure switch contacts are in an open posi- Cooling tion, the control energizes the combustion blower on high...
- Page 55 DIP SWITCH SETTINGS 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 56 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 2 STAGE COMPR...
- Page 57 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 67M41*...
- Page 58 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 67M41*...
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