Lennox International Inc Merit Series Gas Furnace Combustion, Dilution & Ventilation Air

DDo not install the furnace where drafts might blow direct- ly into it. This could cause improper combustion and un- safe operation.

DDo not block the furnace combustion air openings with clothing, boxes, doors, etc. Air is needed for proper combustion and safe unit operation.

DWhen the furnace is installed in an attic or other insu- lated space, keep insulation away from the furnace.

NOTE − The Commonwealth of Massachusetts stipu- lates these additional requirements:

DGas furnaces shall be installed by a licensed plumb- er or fitter only.

DThe gas cock must be

DWhen a furnace is installed in an attic, the passage- way to and service area surrounding the equipment shall be floored.

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 Cal- ifornia 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

Combustion, Dilution & Ventilation Air

In the past, there was no problem in bringing in sufficient out- door air for combustion. Infiltration provided all the air that was needed. In today’s homes, tight construction practices make it necessary to bring in air from outside for combus- tion. Take into account that exhaust fans, appliance vents, chimneys, and fireplaces force additional air that could be used for combustion out of the house. Unless outside air is brought into the house for combustion, negative pressure (outside pressure is greater than inside pressure) will build to the point that a downdraft can occur in the furnace vent pipe or chimney. As a result, combustion gases enter the liv- ing space creating a potentially dangerous situation.

In the absence of local codes concerning air for combus- tion and ventilation, use the guidelines and procedures in this section to install ML180UH furnaces to ensure efficient and safe operation. You must consider combustion air needs and requirements for exhaust vents and gas piping.

A portion of this information has been reprinted with per- mission from the National Fuel Gas Code (ANSI-Z223.1). This reprinted material is not the complete and official posi- tion of the ANSI on the referenced subject, which is repre- sented only by the standard in its entirety.

CAUTION

Do not install the furnace in a corrosive or contami- nated atmosphere. Meet all combustion and ventila- tion air requirements, as well as all local codes.

CAUTION

Insufficient combustion air can cause headaches, nausea, dizziness or asphyxiation. It will also cause excess water in the heat exchanger resulting in rust- ing and premature heat exchanger failure. Excessive exposure to contaminated combustion air will result in safety and performance related problems. Avoid exposure to the following substances in the combus- tion air supply:

Permanent wave solutions Chlorinated waxes and cleaners Chlorine base swimming pool chemicals Water softening chemicals

De-icing salts or chemicals Carbon tetrachloride Halogen type refrigerants

Cleaning solvents (such as perchloroethylene) Printing inks, paint removers, varnishes, etc. Hydrochloric acid

Cements and glues

Antistatic fabric softeners for clothes dryers Masonry acid washing materials

All gas-fired appliances require air for the combustion pro- cess. If sufficient combustion air is not available, the fur- nace or other appliances will operate inefficiently and un- safely. Enough air must be provided to meet the needs of all fuel-burning appliances and appliances such as exhaust fans which force air out of the house. When fireplaces, ex- haust fans, or clothes dryers are used at the same time as the furnace, much more air is necessary to ensure proper combustion and to prevent a downdraft. Insufficient air causes incomplete combustion which can result in carbon monoxide.

In addition to providing combustion air, fresh outdoor air dilutes contaminants in the indoor air. These contami- nants may include bleaches, adhesives, detergents, sol- vents and other contaminants which can corrode furnace components.

The requirements for providing air for combustion and ven- tilation depend largely on whether the furnace is installed in an unconfined or a confined space.

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