Lennox International Inc Merit Series Gas Furnace Use of Furnace as Construction Heater, General

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Installed in Combination with a Cooling Coil

When this furnace is used with cooling units, it shall be installed in parallel with, or on the upstream side of, cooling units to avoid condensation in the heating compartment. See figure 2. With a parallel flow arrangement, a damper (or other means to control the flow of air) must adequately pre- vent chilled air from entering the furnace. 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. See figure 2.

Heating Unit Installed Parallel to Cooling Coil

Dampers

(open during heating operation only)

Gas Unit

Cooling Coil

Dampers

(open during cooling operation only)

Heating Unit Installed Upstream of Cooling Unit

Gas Unit

Cooling Coil

FIGURE 2

When installed, this furnace must be electrically grounded according to local codes. In addition, in the United States, installation must conform with the current National Elec- tric Code, ANSI/NFPA No. 70. The National Electric Code (ANSI/NFPA No. 70) is available from the following ad- dress:

National Fire Protection Association

1 Battery March Park

Quincy, MA 02269

NOTE − This furnace is designed for a minimum continu- ous return air temperature of 60°F (16°C) or an intermit- tent operation down to 55°F (13°C) dry bulb for cases where a night setback thermostat is used. Return air tem- perature must not exceed 85°F (29°C) dry bulb.

The ML180UH furnace may be installed in alcoves, clos- ets, attics, basements, garages, crawl spaces and utility rooms in the upflow or horizontal position.

This furnace design has not been CSA International certified for installation in mobile homes, recreational vehicles, or outdoors.

Use of Furnace as Construction Heater

Lennox does not recommend the use of ML180UH units as a construction heater during any phase of construction. Very low return air temperatures, harmful vapors and op- eration of the unit with clogged or misplaced filters will dam- age the unit.

ML180UH units may be used for heating of buildings or structures under construction, if the following conditions are met:

D The vent system must be permanently installed per these installation instructions.

DA room thermostat must control the furnace. The use of fixed jumpers that will provide continuous heating is not allowed.

DThe return air duct must be provided and sealed to the furnace.

DReturn air temperature range between 60°F (16°C) and 80°F (27°C) must be maintained.

DAir filters must be installed in the system and must be maintained during construction.

DAir filters must be replaced upon construction comple- tion.

DThe input rate and temperature rise must be set per the furnace rating plate.

DOne hundred percent (100%) outdoor air must be pro- vided for combustion air requirements during construc- tion. Temporary ducting may supply outdoor air to the furnace. Do not connect duct directly to the furnace. Size the temporary duct following these instructions in section for Combustion, Dilution and Ventilation Air in a confined space with air from outside.

DThe furnace heat exchanger, components, duct system, air filters and evaporator coils must be thoroughly cleaned following final construction clean−up.

DAll furnace operating conditions (including ignition, in- put rate, temperature rise and venting) must be verified according to these installation instructions.

General

These instructions are intended as a general guide and do not supersede local codes in any way. Consult authorities having jurisdiction before installation.

In addition to the requirements outlined previously, the fol- lowing general recommendations must be considered when installing a ML180UH furnace:

DPlace the furnace as close to the center of the air dis- tribution system as possible. The furnace should also be located close to the chimney or vent termination point.

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Contents Table of Contents Installation Instructions ML180UHTOP View Unit Dimensions − inches mmParts Arrangement Shipping and Packing List Safety InformationML180UH Gas Furnace General Use of Furnace as Construction HeaterCombustion, Dilution & Ventilation Air Equipment in Confined Space ALL AIR from Inside Equipment in Confined Space Setting Equipment Return Air Plenum End Bottom Horizontal Application Installation Clearances Top LeftRight Duct System FiltersUpflow Position VentingTop Vent Discharge Left Side Vent DischargeSide Vent Discharge Horizontal Left PositionHorizontal Right Position Vent Connection Upflow and Horizontal Position Common Venting Using Metal−Lined Masonry Chimney −1/2 18 − The common vent diameter must always be at least as Cated or common venting system, you must inspectFeet FAN + FAN FAN + NAT 112 175 169 278 Carbon Monoxide Poisoning Hazard − In some localities, codes may require the installation Ers or straps. Install a drip leg in vertical pipe runs toGas Piping Every 8 to 10 feet 2.44 to 3.01 m with suitable hangRight−Side Air Discharge Horizontal ApplicationLeft−Side Air Discharge Electrostatic Discharge ESD Interior MAKE−UP BOX InstallationElectrical Thermostat Designations ML180UH Schematic Wiring Diagram and Sequence of Operation Integrated Control Typical ML180UH Field Wiring DiagramUnit Start−Up For Your Safety Read Before LightingHigh Altitude Gas Pressure AdjustmentProper Combustion Manifold Pressure Settings at all Altitudes Other Unit AdjustmentsNo Jumper Heat FAN-OFF Time in Seconds750 453 900680 8851391 Single Side Return Air − Air volumes in bold require field860 653Electrical SHOCK, Fire Or Explosion Hazard ServiceHeat Exchanger Removal ML180UH BURNER, Combustion AIR Inducer Assembly−090, −110 −135 units −045 and −070 unitsPage Repair Parts List Planned ServiceDescription Integrated Control Diagnostic CodesNormal Heating Mode Abnormal Heating Mode Troubleshooting Heating Sequence of OperationHeating Sequence Normal Cooling Mode Abnormal Cooling Mode Troubleshooting Cooling Sequence of OperationContinuous Heat Speed FAN Sequence of Operation Troubleshooting Continuous Fan Sequence of Operation

Merit Series Gas Furnace specifications

Lennox International Inc. is a leading name in the heating and cooling industry, and their Merit Series Gas Furnace embodies the commitment to quality and efficiency that the company is known for. The Merit Series is designed to provide reliable heating in a sustainable manner, making it an excellent choice for homeowners seeking comfort without excessive energy bills.

One of the standout features of the Merit Series Gas Furnace is its efficiency ratings. The units in this series typically boast Annual Fuel Utilization Efficiency (AFUE) ratings of up to 95%. This level of efficiency means that the furnace converts a significant portion of the fuel it uses into heat, ultimately lowering operating costs. Such energy-efficient performance is not only beneficial for the wallet but also promotes environmental sustainability.

The Merit Series also incorporates advanced technologies that enhance its operation. The inclusion of a multi-speed blower motor is a notable feature that provides thoughtful airflow management throughout the home. By adjusting the speed according to the heating needs, the furnace optimizes comfort levels while minimizing noise and energy consumption. Homeowners can enjoy a warm environment without the disruptive sounds often associated with traditional furnaces.

Moreover, the Merit Series comes equipped with durable construction materials designed to withstand the test of time. From the robust heat exchanger to the heavy-gauge cabinet, Lennox focuses on longevity and reliability. This ensures that homeowners can trust their furnace to operate effectively even in the harshest winter conditions.

Safety features are also integral to the design of the Merit Series Gas Furnace. With an integrated Flame Sensor and a built-in safety shut-off system, the furnace ensures that any irregularities in operation are promptly detected and addressed. Such measures provide peace of mind for families using the heating system throughout the cold months.

Installation and maintenance are further simplified with the Merit Series. Its design facilitates easier access for HVAC professionals, allowing for quicker installations and routine service, ensuring that homeowners spend less time and money on upkeep.

In conclusion, Lennox International Inc.'s Merit Series Gas Furnace combines efficiency, advanced technology, and robust construction, making it a top choice for families looking to enhance their home's heating system. With its energy-saving innovations and commitment to reliability, the Merit Series stands as an exemplary option in today’s market.
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