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22
UNIT MAY NOT OPERATE
Failure to follow this caution may result in intermittent unit
operation.
The entire length of furnace MUST be supported when
furnace is used in a horizontal position to ensure proper
draining. When suspended, bottom brace supports sides and
center blower shelf. When unit is supported from the ground,
blocks or pad should support sides and center blower
shelf area.
CAUTION
!
Step 4 -- Air Ducts
GENERAL REQUIREMENTS
The duct system should be designed and sized according to
accepted national standards such as those published by: Air
Conditioning Contractors Association (ACCA), Sheet Metal and
Air Conditioning Contractors National Association (SMACNA)
or American Society of Heating, Refrigerating and Air
Conditioning Engineers (ASHRAE), or consult The Air Systems
Design Guidelines reference tables available from your local
distributor. The duct system should be sized to handle the
required system design CFM at the design static pressure.
PLENUM
OPENING
C
A
B
D
FLOOR
OPENING
A96283
Fig. 21 -- Floor and Plenum Opening Dimensions
DOWNFLOW
SUBBASE
SHEET METAL
PLENUM
FLOOR
OPENING
FURNACE
(OR COIL CASING
WHEN USED)
COMBUSTIBLE
FLOORING
A96285
Fig. 22 -- Furnace, Plenum, and Subbase
Installed on a Combustible Floor
FACTORY SUPPLIED
CASED COIL OR COIL BOX
FURNACE
COMBUSTIBLE
FLOORING
SHEET METAL
PLENUM
FLOOR
OPENING
A07586
Fig. 23 -- Furnace, Plenum, and Coil Assembly or Coil Box
Installed on a Combustible Floor
NO
YES
YES
PERFORATED
DISCHARGE DUCT
FLANGE
210 DEG.
MIN
A93029
Fig. 24 -- Duct Flanges
58MEC