- Do not touch any electrical switch; do not use any phone in your building. - Immediately call your gas supplier froma neighbor’s phone. Follow the gas supplier’s instructions. - If you cannot reach your gas supplier, call the fire department. - Extinguish any open flames. GAS FURNACE Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other appliance. Installation and service must be performed by a qualified installer, service agency or the gas supplier. . 2000 Lennox Industries Inc. Dallas, Texas, USA . If the information in this manual is not followed exactly, a fire or explosion may result causing property damage, personal injury or loss of life. WARNING G40UH(X) Parts Identification UPPER ACCESS PANEL BURNERS COMBUSTION AIR INDUCER BLOWER ACCESS PANEL FLUE COLLAR TOP CAP SURELIGHT. ZZ CONTROL BOARD DURALOKTM HEAT EXCHANGER ASSEMBLY BLOWER MOTOR GAS MANIFOLD CABINET CONTROL BOX GAS VALVE COMBUSTION AIR PROVING (PRESSURE) SWITCH NAMEPLATE FIGURE 1 WARNING Product contains fiberglass wool. Disturbing the insulation in this product during installation, maintenance, or repair will expose you to fiberglass wool. Breathing this may cause lung cancer. (Fiberglass wool is known to the State of California to cause cancer.) Fiberglass wool may also cause respiratory, skin, and eye irritation. To reduce exposure to this substance or for further information, consult material safety data sheets available from address shown below, or contact your supervisor. Lennox Industries Inc. P.O. Box 799900 Dallas, TX 75379-9900 WARNING Do not set thermostat below 60°F (16°C) in heating mode. Setting thermostat below 60°F (16°C) reduces the number of heating cycles. Damage to the unit may occur that is not covered by the warranty. WARNING If overheating occurs or if gas supply fails to shut off, shut off the manual gas valve to the appliance before shutting off electrical supply. CAUTION Before attempting to perform any service or mainte nance, turn the electrical power to unit OFF at the disconnect switch. NOTE-Thismanualmustbeleftwiththeequipment user. Page 2 WARNING Do not use this furnace if any part has been under water. Immediately call a qualified service technician to inspect the furnace and to replace any part of the control system and any gas control which has been under water. IMPORTANT Any additions, changes, or conversions required in order for the appliance to satisfactorily meet the application needs must be made by a Lennox service technician using factory specified and approved parts. WARNING Improper installation, adjustment, alteration, service or maintenance can cause property damage, personal injury or loss of life. Installation and service must be performed by a qualified installer, service agency or the gas supplier. Important Directions 1 -Keep the furnace area clear and free of combustible material, gasoline, and other flammable vapors and liquids. If it is installed in an insulated area, the furnace must be kept free of insulating material. Insulating material may be combustible. 2-DO NOT obstruct air flow to unit. Unit must receive an unobstructed flow of combustion and ventilating air. 3-DO NOT store chlorine or fluorine products near unit or introduce these products into the combustion air. These products can cause furnace corrosion. 4-DO NOT draw return air from a room where this furnace, or any other gas appliance (ie., a water heater), is installed. When return air is drawn from a room, a negative pressure is created in the room. If a gas appliance is operating in a room with negative pressure, the flue products can be pulled back down the vent pipe and into the room. This reverse flow of the flue gas may result in incomplete combustion and the formation of carbon monoxide gas. This toxic gas might then be distributed throughout the house by the furnace duct system. WARNING The blower door must be securely in place when the blower and burners are operating. Gas fumes, which could contain carbon monoxide, can be drawn into the living space resulting in personal injury or death. Your furnace is a gas appliance. It is critical that the gas supplied to the unit be completely burned to avoid the production of carbon monoxide gas. Complete combustion of the gas requires, but is not limited to, correct gas pressure and gas flow rate, adequate combustion, air, and proper venting. WARNING Carbon monoxide gas is invisible, odorless and toxic. Exposure to carbon monoxide gas can cause personal injury and even death to all occupants, including pets. Any item that is powered by or gives off heat from a combustion process (including lawn mowers, automobiles, and fireplaces) has the potential to produce carbon monoxide gas. Because of this, Lennox recommends the use of a carbon monoxide detector in your home, even if you do not own gas appliances. Reliable detectors are available at reasonable retail prices. Contact your Lennox dealer for more details about this in...