Lennox International Inc O23V3-120, O23V-70 Uf U Lj, Wherecondensationofventgasisapparent,thevent

16.Wherecondensationofventgasisapparent,thevent	Combustion Air Requirements
shouldberepairedorreplaced,Accumulationof con-	WARNING
densation in the vent is unacceptable.

17.Vent connectors serving this appliance shall not be connected into any portion of mechanical draft sys- tems operating under positive pressure,

18.Keep the area around the vent terminal free of snow. ice and debris,

NOTE - If vent pipe needs to exit from side of cabinet use the pilot hole (located on either side of the unit) to cut a 6" (152 mm) round hole. Attach finishing plate (provided) with four sheet metal screws to cover rough edges.

CAUTION

Factory-built	Chimney
	FA C TO RY
BAROMETRIC	BUILT
	CHIMNEY
CONTROL*
	/
(IN EITHER_
LOCATION)

\

E

DRAIN FOR

CONDENSATE

D

UF _ U LJ

*Barometric control ma_ be installed in either vertical or horizontal section of flue pipe within 18" of flue outlet of furnace.

Figure 8

Combustion and Ventilation Air (Confined and Unconfined Spaces)

Homes built with energy conservation in mind use tight construction practices. These houses are sealed so well that it becomes necessary to provide a means of bringing in air from outside for combustion, Also, exhaust fans, ap-

pliance vents, chimneys and fireplaces force additional air that could be used for combustion out of the house. Unless

outside air is brought into the home for combustion, nega- tive pressure (pressure outside is greater than inside pres- sure) will build to the point that a down draft can occur in the furnace vent pipe or chimney. Combustion gases enter the living space creating a potentially dangerous situation,

The importance of the previous paragraph cannot be over-

stated. Users may inadvertently block fresh air intakes af- ter installation,

In the absence of local codes concerning air for combus- tion and ventilation, the following section outlines guide-

lines and recommends procedures for operating oil fur- naces in a manner that ensures efficient and safe

operation. Special consideration must be given to combus- tion air needs as well as requirements for exhaust vents and oil piping,

All oil-fired appliances require air to be used for the com- bustion process. If sufficient amounts of combustion air are not available, the furnace or other appliance will oper- ate in an inefficient and unsafe manner. Enough air must be provided to meet the needs of all fuel-burning ap- pliances, as well as appliances such as exhaust fans which force air out of the home. When fireplaces, exhaust fans, or clothes dryers are used at the same time as the furnace, much more air is required to ensure proper combustion and to prevent a down-draft situation. Insufficient amounts of air also cause incomplete combustion which can result in sooting. Requirements for providing air for combustion and ventilation depend largely on whether the furnace is installed in an unconfined or confined space,

Unconfined Space

An unconfined space is an area such as a basement or large equipment room with a volume greater than 50 cubic feet (1.4 cubic meters) per 1,000 Btu (293 W) per hour of the combined input rating of all appliances installed in that space. This space also includes adjacent rooms which are not separated by a door. Though an area may appear to be unconfined, it might be necessary to bring in outdoor air for combustion if the structure does not provide enough air by infiltration. If the furnace is located in a building of tight construction with weather stripping and caulking around the windows and doors, follow the procedures outlined for using air from the outside for combustion and ventilation,

Confined Space

A confined space is an area with volume less than 50 cubic feet (1.4 cubic meters) per 1,000 Btu (293 W) per hour of the combined input rating of all appliances installed in that space. This definition includes furnace closets or small equipment rooms,

When the furnace is installed so that supply ducts carry air circulated by the furnace to areas outside the space con- taining the furnace, the return air must be handled by ducts which are sealed to the furnace casing and which termi- nate outside the space containing the furnace. This is es- pecially important when the furnace is mounted on a plat- form in a confined space (e.g., closet or small equipment room). Even a small leak around the base of the unit at the platform or at the return air duct connection can cause a potentially dangerous negative pressure condition. Air for combustion and ventilation can be brought into the con- fined space either from inside the building or from outside,

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O23V SERIES