Never purge a line into a combustion chamber. Never use
matches, candles, flame, or other sources of ignition to check
for gas leakage. Use a soap-and-water solution to check for
gas leaks. A failure to follow this warning could result in fire,
explosion, personal injury, or death.
Piping should be pressure tested in accordance with local and
national plumbing and gas codes before furnace has been attached.
If test pressure exceeds 0.5 psig (14-in. wc), the gas supply pipe
must be disconnected from furnace and capped before pressure
test. If test pressure is equal to or less than 0.5 psig (14-in. wc),
turn off electric shutoff switch located on the gas valve before test.
It is recommended that ground joint union be loosened before
pressure testing.
Joint compounds (pipe dope) should be applied sparingly and only
to male threads of joints. This pipe dope must be resistant to action
of propane gas.
Install accessible manual shutoff valve upstream of furnace gas
controls and within 72 in. of furnace. A 1/8-in. NPT plugged
tapping is provided on gas value for test gage connection.
Installation of additional 1/8-in. NPT plugged tapping, accessible
for test gage connection, installed immediately upstream of gas
supply connection to furnace and downstream of manual shutoff
valve is not required. Place ground joint union between gas control
manifold and manual shutoff.
Fig. 6—Furnace, Plenum, and Subbase Installed on
a Combustible Floor
A96285
DOWNFLOW
SUBBASE
SHEET METAL
PLENUM
FLOOR
OPENING
FURNACE
(OR COIL CASING
WHEN USED)
COMBUSTIBLE
FLOORING
Fig. 7—Furnace, Plenum, and Coil Assembly or Coil
Box Installed on a Combustible Floor
A96284
CD5 OR CK5
COIL ASSEMBLY
OR KCAKC
COIL BOX
FURNACE
SHEET METAL
PLENUM
FLOOR
OPENING
COMBUSTIBLE
FLOORING
Table 4—Maximum Capacity of Pipe*
NOMINAL
IRON PIPE
SIZE (IN.)
INTERNAL
DIAMETER
(IN.)
LENGTH OF PIPE (FT)
10
20
30
40
50
1/2
0.622
175
120
97
82
73
3/4
0.824
360
250
200
170
151
1
1.049
680
465
375
320
285
1-1/4
1.380
1400
950
770
660
580
1-1/2
1.610
2100
1460
1180
990
900
* Cubic ft of gas per hr for gas pressures of 0.5 psig (14-in. wc) or less, and a
supply line pressure drop of 0.5-in. wc (based on a 0.60 specific gravity gas).
Ref: Table 10-2, NFPA 54-1996.
Fig. 8—Downflow Filter Arrangement
A88486
RETURN-AIR
PLENUM
AIRFLOW
ACCESS DOOR
INSTALLATION
POSITION
OF FILTERS
8
