Carrier 48NLT - Manual (Page 6)

r MIN
Condensate water can be drained directly onto the roof in
rooftop installations (where permitted) or onto a gravel apron
in ground-level installations. When using a gravel apron,
make sure it slopes away from the unit.
Step 6 — Install Venting — The vent cap assembly
is shipped in the burner compartment. Remove the access
door to locate the assembly.
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. Make sure they are
oriented properly 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.
2. Secure vent cap in place by inserting the single screw on
the right side of vent cap.
3. Place the vent cap guard over the vent cap. Orient holes
in vent cap guard with holes in vent cap and flue panel.
4. Secure the entire assembly with the remaining 2 screws
on the left side of vent cap and vent-cap guard
assembly.
Step 7 — 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 Vi-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 2 and the
National Fuel Gas Code (NFGC) for gas pipe sizing.
Do
not use cast-iron pipe. It is recommended that black iron
pipe is used. Check the local utility for recommendations
concerning 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 ‘A-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 5 in. wg or greater than
13 in. wg while the unit is operating. For propane applica­
tions, the gas pressure must not be less than 11 in. wg or
greater than 13 in. wg at the unit connection.
When installing the gas supply line, observe local codes
pertaining to gas pipe installations. Refer to the NFGC ANSI
(American National Standards Institute) Z223.1-1988 NFPA
(National Fire Protection Association) 54-1988 (in Canada,
CAN/CGA [Canadian Gas Association] B 149.1, (2)-M86).
In the absence of local building codes, adhere to the fol­
lowing pertinent recommendations:
1. Avoid low spots in long runs of pipe. Grade all pipe
V4 inch 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 Уг 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 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.
This drip leg functions as a trap for dirt and condensate.
Install trap where condensate cannot 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, connect capped nipple into
lower end of tee. Extend capped nipple below level of
gas controls.
Table 2 — Maximum Gas Glow Capacity*
NOMINAL
IRON PIPE,
SIZE
(in.)
INTERNAL
DIAMETER
(In.)
LENGTH OF PIPE, FTf
10 20 30 40 50 60 70 80 90 100 125 150 175 200
V2 .622 175 120 97 82 73 66 61 57 53 50 44 40 — —
% .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
VA 1.380 1400 950 770 600 580 530 490 460 430 400 360 325 300 280
VA 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 less. Pressure drop of 0.5 in. wg
(based on a 0.60 specific gravity gas) Refer to Table C-4, NFPA 54-1984
fThls length includes an ordinary number of fittings