9
Table 2 – Maximum Gas Flow Capacity*
NOMINAL
IRON PIPE,
SIZE (IN.)
INTERNAL
DIAMETER
(IN.)
LENGTH OF PIPE, FT†
10
20
30
40
50
60
70
80
90
100
125
150
175
200
1/2
.622
175
120
97
82
73
66
61
57
53
50
44
40
—
—
3/4
.824
360
250
200
170
151
138
125
118
110
103
93
84
77
72
1
1.049
680
465
375
320
285
260
240
220
205
195
175
160
145
135
11/4
1.380
1400
950
770
600
580
530
490
460
430
400
360
325
300
280
11/2
1.610
2100
1460
1180
990
900
810
750
690
650
620
550
500
460
430
* Capacity of pipe in cu ft of gas per hr for gas pressure of 0.5 psig or Protection Association NFPA 54. less. Pressure drop of 0.5--in. wc (based on a 0.60 specific
gravity gas). Refer to Table, National Fire
† This length includes an ordinary number of fittings.
Step 8 — INSTALL GAS PIPING
The gas supply pipe enters the unit through the access hole
provided. The gas connection to the unit is made to the 1/2--in.
FPT gas inlet on the manual shutoff or gas valve.
Install a gas supply line that runs to the heating section. Refer to
Table 2 and the NFGC for gas pipe sizing. Do not use cast--iron
pipe. It is recommended that a black iron pipe is used. Check the
local utility for recommendations concerning existing lines. Size
gas supply piping for 0.5 in. wc maximum pressure drop. Never
use pipe smaller than the 1/2--in. FPT gas inlet on the unit gas
valve.
For natural gas applications, the gas pressure at unit gas
connection must not be less than 4.0 in. wc or greater than 13 in.
wc while the unit is operating. For propane applications, the gas
pressure must not be less than 7.0 in. wc or greater than 13 in. wc
at the unit connection.
An 1/8--in. NPT plugged tapping, accessible for test gage
connection, must be installed immediately upstream of the gas
supply connection to the gas valve.
When installing the gas supply line, observe local codes
pertaining to gas pipe installations. Refer to the NFGC ANSI
Z223.1--1988 NFPA latest edition (in Canada, CAN/CGA
B149.1, (2)--M86). In the absence of local building codes, adhere
to the following pertinent recommendations:
1. Avoid low spots in long runs of pipe. Grade all pipe 1/4
in. in every 15 ft to prevent traps. Grade all horizontal runs
downward to risers. Use risers to connect to heating
section and to meter.
2. Protect all segments of piping system against physical and
thermal damage. Support all piping with appropriate
straps, hangers, etc. Use a minimum of one hanger every 6
ft. For pipe sizes larger than 1/2 in., follow
recommendations of national codes.
3. Apply joint compound (pipe dope) sparingly and only to
male threads of joint when making pipe connections. Use
only pipe dope that is resistant to action of liquefied
petroleum gases as specified by local and/or national
codes. Never use Teflon tape.
4. Install sediment trap in riser leading to heating section
(See Fig. 8). This drip leg functions as a trap for dirt and
condensate.
5. Install an accessible, external, manual main shutoff valve
in gas supply pipe within 6 ft of heating section.
6. Install ground--joint union close to heating section
between unit manual shutoff and external manual main
shut--off valve.
7. Pressure--test all gas piping in accordance with local and
national plumbing and gas codes before connecting piping
to unit.
NOTE
: Pressure test the gas supply system after the gas supply
piping is connected to the gas valve. The supply piping must be
disconnected from the gas valve during the testing of the piping
systems when test pressure is in excess of 0.5 psig. Pressure test
the gas supply piping system at pressures equal to or less than 0.5
psig. The unit heating section must be isolated from the gas
piping system by closing the external main manual shutoff valve
and slightly opening the ground--joint union.
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal injury,
death and/or property damage.
--Connect gas pipe to unit using a backup wrench to avoid
damaging gas controls.
--Never purge a gas line into a combustion chamber. Never test
for gas leaks with an open flame. Use a commercially available
soap solution made specifically for the detection of leaks to
check all connections.
--Use proper length of pipe to avoid stress on gas control
manifold.
--If a flexible connector is required or allowed by authority
having jurisdiction, black iron pipe shall be installed at furnace
gas valve and extend a minimum of 2 in. outside furnace casing.
--If codes allow a flexible connector, always use a new
connector. do not use a connector which has previously
serviced another gas appliance.
!
WARNING
8. Check for gas leaks at the field--installed and
factoryinstalled gas lines after all piping connections have
been completed. Use soap--and--water solution (or method
specified by local codes and/or regulations).
OUT
TEE
NIPPLE
CAP
IN
C99020
Fig. 8 -- Sediment Trap
Step 9 — INSTALL DUCT CONNECTIONS
The unit has duct flanges on the supply-- and return--air openings
on the side and bottom of the unit. For downshot applications, the
ductwork connects to the roof curb (See Fig. 2 and 3 for
connection sizes and locations).
574B
