Lenox Lennox Merit Series Gas Furnace Upflow/Horizontal air discharge, ML180UHE General

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 Coil

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 ML180UHE 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 ML180UHE 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.

ML180UHE 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 ML180UHE 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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