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Lennox ML180DF Installation Instructions Manual

Merit series gas furnace downflow air discharge
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E 2015 Lennox Industries Inc.
Dallas, Texas, USA
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DOWNFLOW
AIR FLOW

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INSTALLATION
INSTRUCTIONS
ML180DF
®
MERIT
SERIES GAS FURNACE
DOWNFLOW AIR DISCHARGE
507326-01
06/2015
Supersedes 507057-01
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.
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, person­
al injury or loss of life. Installation and service must
be performed by a licensed professional installer (or
equivalent), service agency or the gas supplier.
As with any mechanical equipment, personal injury
can result from contact with sharp sheet metal
edges. Be careful when you handle this equipment.
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WARNING
CAUTION
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Summary of Contents for Lennox ML180DF

  • Page 1: Table Of Contents

    INSTALLATION INSTRUCTIONS E 2015 Lennox Industries Inc. Dallas, Texas, USA ML180DF ® MERIT SERIES GAS FURNACE DOWNFLOW AIR DISCHARGE 507326-01 06/2015 Litho U.S.A. Supersedes 507057-01 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.

  • Page 2: Unit Dimensions

    Unit Dimensions - inches (mm) 3−1/8 9/16 (79) (14) RETURN AIR OPENING FLUE OUTLET 19−7/16 9/16 (Top) (494) (14) 9/16 (14) TOP VIEW 3/4 (19) 27−3/4 (705) Front Panel 9/16 19−7/16 9/16 (14) (494) (14) ELECTRICAL INLET (Either Side) (838) 5−3/8 (137) Right GAS PIPING INLET 2−1/8 (54) Left...

  • Page 3: Ml180Df Gas Furnace

    Failure to do so may cause erratic limit operation and may also result in premature heat exchanger failure. WARNING This ML180DF furnace must be installed so that its electri­ Improper installation, adjustment, alteration, service cal components are protected from water.

  • Page 4: Use Of Furnace As A Construction Heater

    Air is needed for proper combustion and safe unit operation. Lennox does not recommend the use of ML180DF units as When the furnace is installed in an attic or other insu­ a construction heater during any phase of construction.

  • Page 5: Combustion, Dilution & Ventilation Air

    The requirements for providing air for combustion and ven­ this section to install ML180DF furnaces to ensure efficient tilation depend largely on whether the furnace is installed in and safe operation. You must consider combustion air an unconfined or a confined space.
  • Page 6 especially important when the furnace is mounted on a space. Each opening must be at least 100 square inches platform in a confined space such as a closet or small (64516 mm ). One opening shall be within 12 inches (305 equipment room.
  • Page 7 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) 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.
  • Page 8 Installation on Non-Combustible Flooring (Figure 6) 1 - Cut floor opening keeping in mind clearances listed on unit rating plate. Also keep in mind gas supply connec­ ML180DF UNIT tions, electrical supply, flue and air intake connections and sufficient installation and servicing clearances.

  • Page 9: Setting Equipment

    PROPERLY PLENUM SIZED FLOOR OPENING Install the ML180DF gas furnace as shipped in the down­ flow position only. Do not install the furnace hori­ zontally. Select a location that allows for the required clearances that are listed on the unit nameplate. Also consider gas...

  • Page 10: Filters

    Horizontal Front Back FIGURE 12 Downflow Application CAUTION Allow for clearances to combustible materials as indicated on the unit nameplate. Minimum clearances for closet or al­ If this unit is being installed in a space serviced by an exhaust fan, power exhaust fan, or other device cove installations are shown in figure 13.

  • Page 11: Duct System

    The ML180DF series units are classified as fan-assisted flue transition. If self-drilling screws are used to attach the Category I furnaces when vertically vented according to vent pipe, it is recommended that three be used.
  • Page 12 OTHER suitable materials, or replaced with a gas vent or chimney APPLIANCE suitable for venting ML180DF series units. The chimney PERMANENTLY SEALED FIREPLACE passageway must be checked periodically to ensure that it OPENING is clear and free of obstructions.
  • Page 13 5 (127) 7-1/2 (2.29) General Venting Requirements 6 (152) 9 (2.74) Vent all ML180DF furnaces according to these instruc­ 7 (178) 10-1/2 (3.20) tions: 9 - If the common vertical vent is offset, the maximum 1 - Vent diameter recommendations and maximum allow­...
  • Page 14 19 - In no case, shall the vent connector be sized more than cated or common venting system, you must inspect the two consecutive table size diameters over the size of venting system's general condition and look for signs the draft hood outlet or flue collar outlet. of corrosion.
  • Page 15 TABLE 6 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) Vent Connector 3 Inch 4 Inch 5 Inch 6 Inch Height Rise Appliance Input Rating in Thousands of Btu Per Hour (feet) (feet)

  • Page 16: Gas Piping

    Removal of the Furnace from Common Vent Resize the common venting system to the minimum vent pipe size determined by using the appropriate In the event that an existing furnace is removed from a tables in Appendix G. (These are in the current stan­ venting system commonly run with separate gas ap­...
  • Page 17 TABLE 8 Gas Pipe Capacity - ft /hr (m /hr) Nominal Length of Pipe - feet (m) Internal Iron Pipe Diameter Size inches inches (mm) (3.048) (6.096) (9.144) (12.192) (15.240) (18.288) (21.336) (24.384) (27.432) (30.480) (mm) .622 (12.7) (17.799) (4.87) (3.34) (2.69) (2.29)

  • Page 18: Electrical

    Leak Check The unit is equipped with a field make-up box on the left hand side of the cabinet. The make-up box may be moved After gas piping is completed, carefully check all piping to the right side of the furnace to facilitate installation. If the connections (factory- and field-installed) for gas leaks.
  • Page 19 One line voltage “HUM” 1/4” spade terminal is provided on 2 - When the ML180DF is running in the heating mode, the furnace integrated control. See figure 21 for integrated the indoor blower will run on the heating speed.
  • Page 20 ML180DF Schematic Wiring Diagram FIGURE 20 Page 20...

  • Page 21: Integrated Control

    Integrated Control INTEGRATED CONTROL (Automatic Hot Surface Ignition System) TERMINAL DESIGNATIONS Humidifier (120VAC) Input (120VAC) LINE Transformer (120VAC) XFMR Indoor Air Qality Accessory Air Cleaner (120VAC) Blower - Cooling Speed (120VAC) COOL Blower - Heating Speed (120VAC) HEAT Dead terminals to park alternate spd taps PARK Continuous blower CONT...

  • Page 22: Unit Start-Up

    “Turning Off Gas to Unit” and call your service techni­ The gas valve on the ML180DF unit is equipped with a gas cian or gas supplier. control switch. Use only your hand to move the switch. Nev­...

  • Page 23: Gas Pressure Adjustment

    The maximum car­ Seconds for One Revolution bon monoxide reading should not exceed 50 ppm. Natural TABLE 10 ML180DF Unit 1 cu ft 2 cu ft 1 cu ft 2 cu ft ML180DF Unit...

  • Page 24: Other Unit Adjustments

    TABLE 11 Manifold Pressure Settings at all Altitudes Supply Pressure Model in.wg. 0-4500 ft 4501-7500 ft 7501 - 10,000 ft Input Size 13.0 LP/propane 10.0 10.0 10.0 11.0 13.0 13.0 LP/propane 10.0 10.0 10.0 11.0 13.0 13.0 LP/propane 10.0 10.0 10.0 11.0 13.0...
  • Page 25 9 - Recheck temperature rise. 60 Second 90 Second 120 Second 180 Second Twinning 2 ML180DF Furnaces off Time off Time off Time off Time The control board in this furnace is equipped with a provi­ sion to ”twin” (interconnect) two(2) adjacent furnaces with a common plenum such that they operate as one (1) large unit.

  • Page 26: Service

    FIGURE 24 Annual Furnace Maintenance Service At the beginning of each heating season, and to comply with the Lennox Limited Warranty, your system should be checked by a licensed professional technician (or equiv­ alent) as follows: WARNING 1- Check wiring for loose connections, voltage at indoor...
  • Page 27 tion procedure. This procedure can be viewed at manifold pressure adjustment is necessary, consult the Service Literature for unit specific information on www.ahrinet.org adjusting gas pressure. Not all gas valves are ad­ 9- Ensure sufficient combustion air is available to the fur­ justable.

  • Page 28: Repair Parts

    FIGURE 25 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: ML180DF110P60C-01. All service must be performed by a licensed professional installer (or equivalent), service agency, or gas supplier.

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