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© 2024 Lennox Industries Inc.
Dallas, Texas USA
WARNING
installation,
Improper
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.
Contents
Unit Dimensions - inches (mm........................................2
ML180UHV Gas Furnace ...............................................3
Shipping and Packing List ..............................................3
Safety .............................................................................3
Use of Furnace as a Construction Heaterl .....................4
General ...........................................................................4
Combustion, Dilution, Ventilation Air...............................5
Setting Equipment ..........................................................8
Filters ............................................................................ 11
Duct System .................................................................12
Venting .........................................................................13
adjustment,
alteration,
INSTALLATION
INSTRUCTIONS
ML180UHV
MERIT
SERIES
®
HORIZONTAL AIR DISCHARGE
507945-02
04/2024
Supersedes 08/2023
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.
IMPORTANT
DO NOT use the bracket securing the heat exchanger
to lift, drag or pull the furnace to its installation
location. Doing so will loosen the bracket causing
noise and or unsafe operation.
Bracket
Gas Piping ....................................................................20
Electrical .......................................................................22
Integrated Control .........................................................25
Unit Start-Up .................................................................29
Gas Pressure Measurement.........................................30
Proper Combustion.......................................................30
High Altitude .................................................................30
Other Unit Adjustments.................................................32
Service..........................................................................32
Blower Data ..................................................................35
Page 1
GAS
FURNACE
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Related Manuals for Lennox MERIT ML180UHV030V36A
Summary of Contents for Lennox MERIT ML180UHV030V36A
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Page 1: Table Of Contents
INSTALLATION INSTRUCTIONS ML180UHV © 2024 Lennox Industries Inc. Dallas, Texas USA MERIT SERIES FURNACE ® HORIZONTAL AIR DISCHARGE 507945-02 04/2024 Supersedes 08/2023 THIS MANUAL MUST BE LEFT WITH THE HOMEOWNER FOR FUTURE REFERENCE This is a safety alert symbol and should never be ignored. -
Page 2: Unit Dimensions - Inches
Unit Dimensions - inches (mm) 3-1/8 (79) NOTE - 60C 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 20 x 25 x 1 inch (508 x 635 x 25 mm) air filter to maintain proper velocity. -
Page 3: Ml180Uhv Gas Furnace
Certifications ML180UHV Gas Furnace ML180UHV units are CSA International certified to ANSI The ML180UHV unit is shipped ready for installation in the Z21.47. upflow or horizontal right position (for horizontal left posi- In the USA, installation of gas furnaces must conform with tion the combustion air pressure switch must be moved) local building codes. -
Page 4: Use Of Furnace As A Construction Heaterl
Use of Furnace as Construction Heater distribution system as possible. The furnace should Lennox does not recommend the use of ML180UHV units also be located close to the chimney or vent termi- as a construction heater during any phase of construc- nation point. -
Page 5: Combustion, Dilution, Ventilation Air
• Do not install the furnace where drafts might blow CAUTION directly into it. This could cause improper combus- Insufficient combustion air can cause headaches, tion and unsafe operation. nausea, dizziness or asphyxiation. It will also cause • Do not block the furnace combustion air openings excess water in the heat exchanger resulting in with clothing, boxes, doors, etc. - Page 6 Confined Space Air from Inside f the confined space that houses the furnace adjoins a A confined space is an area with a volume less than 50 space categorized as unconfined, air can be brought in cubic feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of by providing two permanent openings between the two the combined input rating of all appliances installed in that space.
- 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) 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 8: Setting Equipment
Upflow Applications Setting Equipment Allow for clearances to combustible materials as indicated WARNING on the unit nameplate. Minimum clearances for closet or alcove installations are shown in FIGURE 7. Do not install the furnace on its front or its back. Do not connect the return air ducts to the back of the Upflow Application Installation Clearances furnace. - Page 9 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.
- Page 10 Pivot the bottom cap down to release the bottom plications. Order horizontal suspension kit (51W10) from panel. Once the bottom panel has been removed, reinstall Lennox, or use equivalent suspension method. the bottom cap. See FIGURE 10. Allow for clearances to combustible materials as indicated on the unit nameplate.
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Page 11: Filters
In platform installations with bottom return air, the specifications provided by the filter manufacturer furnace should be sealed airtight to the return air against the data given in the appropriate Lennox plenum. A door must never be used as a portion of Product Specifications bulletin. -
Page 12: Duct System
Return Air Plenum Duct System NOTE - Return air must not be drawn from a roomwhere Use industry-approved standards (such as those pub- this furnace, or any other gas-fueled appliance (i.e., water lished by Air Conditioning Contractors of America or Amer- heater), or carbon monoxide producing device (i.e., wood ican Society of Heating, Refrigerating and Air Condition- fireplace) is installed. -
Page 13: Venting
1 - Remove the four mounting screws (FIGURE Venting 15) which secure the combustion air inducer / A 4-inch diameter flue transition is factory-installed on the pressure switch assembly to the orifice plate. Lift combustion air inducer outlet of all models. FIGURE 16 the assembly and rotate it 90 degrees clockwise shows the combustion air inducer as shipped from the or counterclockwise to either the 3 o’clock position... - Page 14 HORIZONTAL LEFT POSITION HORIZONTAL RIGHT POSITION Top Vent Discharge Top Vent Discharge Vent Pipe Vent Pipe Pressure Switch Pressure Flue Switch Transition Cover Plate Flue Transition Collector Box FLOW FLOW Make-Up Box Cover Plate Collector Box Make-Up Box Disconnect pressure switch hose from barbed fitting on the pressure switch assembly.
- Page 15 The ML180UHV series units are classified as fan-assisted Venting Using a Masonry Chimney Category I furnaces when vertically vented according to The following additional requirements apply when a lined the latest edition of National Fuel Gas Code (NFPA 54 / masonry chimney is used to vent this furnace.
- Page 16 When inspection reveals that an existing chimney is not Common Venting Using Metal-Lined Masonry Chimney safe for the intended purpose, it shall be rebuilt to conform to nationally recognized standards, lined or relined with SEALED suitable materials, or replaced with a gas vent or chimney suitable for venting ML180UHV series units.
- Page 17 Common Venting Using Tile-Lined Interior Masonry Chimney and Combined Vent Connector MINIMUM LENGTH = AS SHORT AS PRACTICAL. INTERIOR TILE-LINED FOR MAXIMUM LENGTH SEE NOTE TO LEFT MASONRY CHIMNEY NOTE- Refer to provided venting tables for installations. NOTE - the chimney must be properly sized per provided venting tables or lined with listed metal lining system.
- Page 18 17 - If vent connectors are combined prior to entering 20 - Do not install a manual damper, barometric draft the common vent, the maximum common vent regulator or flue restrictor between the furnace and capacity listed in the common venting tables must the chimney.
- Page 19 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...
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Page 20: Gas Piping
Removal of the Furnace from Common Vent Gas Piping In the event that an existing furnace is removed from a Gas supply piping should not allow more than 0.5”W.C. venting system commonly run with separate gas applianc- drop in pressure between gas meter and unit. Supply gas es, the venting system is likely to be too large to properly pipe must not be smaller than unit gas connection. - Page 21 TABLE 6 Gas Pipe Capacity - ft3/hr (m3/hr) Nominal Internal Length of Pipe - feet (m) 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) (4.87) (3.34) (2.69) (2.29) (2.03) (1.84)
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Page 22: Electrical
Horizontal Applications Possible Gas Piping Configurations MANUAL MAIN SHUT-OFF VALVE MANUAL Horizontal Application MAIN SHUT-OFF Left-Side Air Discharge VALVE GROUND JOINT UNION GROUND JOINT DRIP LEG UNION DRIP LEG MANUAL MAIN SHUT-OFF VALVE FIELD PROVIDED GROUND JOINT INSTALLED UNION Horizontal Application NOTE - BLACK IRON PIPE ONLY TO BE ROUTED INSIDE OF CABINET DRIP LEG Right-Side Air Discharge... - Page 23 Electrically ground the unit according to local codes or, in INTERIOR MAKE-UP BOX INSTALLATION the absence of local codes, according to the current Na- tional Electric Code (ANSI/NFPA No. 70). A green ground wire is provided in the field make-up box. Right Side NOTE - The ML180UHV furnace contains electronic com- ponents that are polarity sensitive.
- Page 24 ML180UHV Schematic Wiring Diagram and Sequence of Operation Line voltage is applied to L1 and N. the T1 low voltage transformer is energized, and line voltage is applied to B3 indoor blower. S47 rollout switch(es) must be closed in order for 24V from transformer to be output on integrated control ”R” to power thermostat. When there is a call for heat, W1 of the thermostat energizes W of the furnace control with 24VAC.
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Page 25: Integrated Control
Integrated Control INTEGRATED CONTROL (Automatic Hot Surface Ignition System) RED LED OPTION JUMPERS RECALL BUTTON FIGURE 31 TABLE 7 1/4” QUICK CONNECT TERMINALS Humidifier 120VAC LINE 120VAC XFMR Transformer 120VAC CIRC Indoor blower 120VAC Indoor air qualityaccessory 120VAC NEUTRAL Common 120VAC 3/16”... - Page 26 Integrated Control Diagnostic Codes RED LED Diagnostic Codes / Status of Furnace Flash Code No power to control or board fault detected Board fault detected, Heartbeat Normal Operation - Idle, Continuous Fan, Cool Continuous Rapid Flash Call For Heat / Burner Operation Reverse Line Voltage Polarity Improper Earth Ground Burner failed to light, or lost flame during heat demand...
- Page 27 Variable Speed Features TABLE 8 This furnace is equipped with a variable speed circulation Heating Mode air blower motor that will deliver a constant airflow within a Heat Air Flow DIP3 DIP4 wide range of external static pressures. Other features of High this variable speed motor include: Med-High...
- Page 28 To engage the continuous blower operation, place the Two Stage Cooling FIGURE 34 fan switch on the thermostat into the ON position. A call A call for 1st stage cooling from the thermostat closes for fan from the thermostat closes R to G on the ignition the R to Y circuit on the control board.
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Page 29: Unit Start-Up
5 - Remove the upper access panel. Unit Start-Up 6 - Move switch on gas valve to OFF. Do not force. See FOR YOUR SAFETY READ BEFORE LIGHTING FIGURE 35 and FIGURE 36. WARNING 7 - Wait five minutes to clear out any gas. If you then smell gas, STOP! Immediately call your gas supplier Do not use this furnace if any part has been from a neighbor’s phone. -
Page 30: Gas Pressure Measurement
NOTE - Pressure test adapter kit (10L34) is available from 1 - When thermostat calls for heat, combustion air blower starts. Lennox to facilitate manifold pressure measurement. 1 - Connect test gauge to manifold pressure post on 2 - Combustion air pressure switch proves blower gas valve. - Page 31 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 13 Supply Line and Manifold Pressure Settings at all Altitudes Line Pressure in. wg. Model 7501 - 10,000 0 - 2000 ft.
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Page 32: Other Unit Adjustments
Thermostat Heat Anticipation Other Unit Adjustments Set the heat anticipator setting (if adjustable) according to Primary and Secondary Limits the amp draw listed on the wiring diagram that is attached The primary limit is located on the heating compartment to the unit. vestibule panel. - Page 33 Check for At the beginning of each heating season, and to comply air leaks on supply and return ducts and seal where with the Lennox Limited Warranty, your system should be necessary. checked by a licensed professional technician (or equiva-...
- Page 34 Cleaning the Burners 4 - To clean burners, run a vacuum cleaner with a soft brush attachment over the face of burners. Visually NOTE - Use papers or protective covering in front of the inspect inside the burners and crossovers for any furnace during cleaning.
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Page 35: Blower Data
Blower Data TABLE 16 Allowable Heating Speeds ML180V Model Speed Adjust MED LOW MED HIGH HIGH +10% Allowed 030V36A Norm Factory Setting Allowed -10% Allowed +10% Allowed 045V36A Norm Factory Setting -10% Allowed Not Allowed +10% Allowed 070V36A Norm Factory Setting -10% Allowed +10%... - Page 36 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 - minimum 350 cfm. Lennox Harmony III™ Zoning System Applications - Minimum blower speed is 350 cfm. BL O WER D ATA...
- Page 37 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 - minimum 350 cfm. Lennox Harmony III™ Zoning System Applications - Minimum blower speed is 350 cfm. BL O WER D ATA...
- Page 38 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 - minimum 400 cfm. Lennox Harmony III™ Zoning System Applications - Minimum blower speed is 400 cfm. BL O WER D ATA...
- Page 39 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 - minimum 550 cfm. Lennox Harmony III™ Zoning System Applications - Minimum blower speed is 550 cfm. Page 39...