INTAKE PIPE | *GAS CONNECTION |
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EXHAUST PIPE |
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SERVICE PLATFORM | RAISED | |
PLATFORM | ||
FIGURE 19
Return Air
Return air may be brought in only through the end of a fur nace installed in the horizontal position. The furnace is equipped with a removable bottom panel to facilitate instal lation. See figure 15.
Filters
This unit is not equipped with a filter or rack. A
ate properly. Table 1 lists recommended filter sizes.
A filter must be in place whenever the unit is operating.
IMPORTANT
If a highefficiency filter is being installed as part of this system to ensure better indoor air quality, the fil ter must be properly sized. Highefficiency filters have a higher static pressure drop than standardef ficiency glass/foam filters. If the pressure drop is too great, system capacity and performance may be re duced. The pressure drop may also cause the limit to trip more frequently during the winter and the indoor coil to freeze in the summer, resulting in an increase in the number of service calls.
Before using any filter with this system, check the specifications provided by the filter manufacturer against the data given in the appropriate Lennox Product Specifications bulletin. Additional informa tion is provided in Service and Application Note ACC002 (August 2000).
TABLE 1
Furnace | Filter Size | |
Cabinet Width | Side Return | Bottom Return |
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16 X 25 X 1 (1) | 16 X 25 X 1 (1) | |
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21” | 16 X 25 X 1 (1) | 20 X 25 X 1 (1) |
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16 X 25 X 1 (2) | 24 X 25 X 1 (1) | |
Page 13
Duct System
Use industry‐approved standards to size and install the supply and return air duct system. Refer to ACCA Manual D. This will result in a quiet and low‐static system that has uniform air distribution.
NOTE - This furnace is not certified for operation in heating mode (indoor blower operating at selected heating speed) with an external static pressure which exceeds 0.5 inches w.c. Operation at these conditions may result in improper limit operation.
Supply Air Plenum
If the furnace is installed without a cooling coil, a removable access panel should be installed in the supply air duct. The access panel should be large enough to permit inspection of the heat exchanger. The furnace access panel must al ways be in place when the furnace is operating and it must not allow leaks.
Return Air Plenum
NOTE - Return air must not be drawn from a room where this furnace, or any other
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 re verse flow of the flue gas may result in incomplete com bustion and the formation of carbon monoxide gas. This raw gas or toxic fumes might then be distributed throughout the house by the furnace duct system.
Return air can be brought in through the bottom or either side of the furnace (return air brought into either side fur nace allowed in upflow applications only). If a furnace with bottom return air is installed on a platform, make an airtight seal between the bottom of the furnace and the platform to ensure that the unit operates properly and safely. Use fi berglass sealing strips, caulking, or equivalent sealing method between the plenum and the furnace cabinet to en sure a tight seal. If a filter is installed, size the return air duct to fit the filter frame.
Pipe & Fittings Specifications
All pipe, fittings, primer and solvent cement must conform with American National Standard Institute and the Ameri can Society for Testing and Materials (ANSI/ASTM) stan dards. The solvent shall be free flowing and contain no lumps, undissolved particles or any foreign matter that ad versely affects the joint strength or chemical resistance of the cement. The cement shall show no gelation, stratifica tion, or separation that cannot be removed by stirring. Re fer to the table 2 below for approved piping and fitting ma terials.
