Carrier 48N - Manual (Page 5)

Table 1—Maximum Gas Flow Capacity of Pipe in Cubic Feet of Gas Per Hour for Gas
Pressures of 0.5 PSIG or Less and a Pressure Drop of 0.5 inch Water Coiumn
(Based on a 0.60 Specific Gravity Gas)
Nominal
Iron Pipe,
Size,
Inches
Internal
Diameter,
Inches
Length of Pipe, Feet*
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 1.049 680 455 375 320 285 260 240 220 205 195 175 160 145 135
1-1/4 1.380 1,400 950 770 600 580 530 490 460 430 400 360 325 300 280
1-1/2 1.610 2,100 1,460 1,180 990 900 810 750 690 650 620 550 500 460 430
Ref: Table 0^4, NFPA 54—1984
*This length includes an ordinary number of fittings.
A CAUTION
The venting system is designed to ensure proper vent­
ing. The vent cap assembly must be installed as indi­
cated
in this section of the unit Installation
Instructions.
NOTE: Screw holes in the flue assembly and the unit flue
panel are not symmetrically located; thereby, ensuring
proper orientation when installing these components.
Refer to Fig. 6 and install the vent cap as follows:
1. Place vent cap assembly over flue panel, orient screw
holes in vent cap with holes in flue panel, and secure
vent cap in place by inserting the single screw on the
right side of vent cap.
2. Place the vent cap guard over the vent cap, orient holes
in vent cap guard with holes in vent cap and flue panel.
Secure the entire assembly with the remaining two
screws on the left side of vent cap and vent cap guard
assembly.
Step 4—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 separate gas supply line that runs directly from
the meter to the heating section. Refer to Table 1 and the
National Fuel Gas Code for gas pipe sizing.
Do not use cast-
iron pipe. Check the local utihty for recommendations con­
cerning existing lines. Choose a supply pipe that is large
enough to keep the pressure loss as low as practical.
Never
use pipe smaller than the 1/2-in. FPT gas inlet on the unit
gas valve.
When instaUing the gas supply hne, observe local codes per­
taining to gas pipe installations. Refer to the National Fuel
Gas Code ANSI Z223.1-1984 (In Canada, CAN/CGA
B 149.1, (2)-M86) or NFPA 54-1984 in the absence of local
buUding codes. Adhere to the following pertinent recom­
mendations:
1. Avoid low spots in long runs of pipe. Grade aU pipe
1/4-in. in every 15-ft to prevent traps. Grade all hori­
zontal 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 appropri­
ate straps, hangers, etc. Use a minimum of one hanger
every 6-ft. For pipe sizes larger than 1/2-in., follow rec­
ommendations 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 lique­
fied petroleum gases as specified by local and/or
national codes.
Never use teflon tape.
5.
6
.
4. Install sediment trap in riser leading to heating sec­
tion. This drip leg functions as a trap for dirt and con­
densate. Install trap where condensate can not freeze.
Install this sediment trap by connecting a piping tee to
riser leading to heating section, so that straight-
through section of tee is vertical. See Fig. 7. Then, con­
nect capped nipple into lower end of tee. Extend
capped nipple below level of gas controls.
Install an accessible, external, manual main shut-off
valve in gas supply pipe within 6-ft of heating section.
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: When pressure testing the gas supply system after
the gas supply piping has been coimected to the unit gas
valve, the supply piping must be disconnected from the gas
vedve during any pressure testing of the piping systems at
test pressure in excess of 0.5 psig. When pressure testing
the gas supply piping system at test 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 shut-off valve and slightly opening the ground-joint
union.
Fig. 6—Vent Cap Assembly