Carrier SINGLE PACKAGE ROOFTOP UNITS ELECTRIC COOLING/GAS HEATING 48HJ015-025 - Manual (Page 8)

Step 6 — Trap Condensate Drain — See Fig. 11
for drain location. One 3 ⁄
4
-in. half coupling is provided
inside unit evaporator section for condensate drain connec-
tion. An 8
1 ⁄
2
in. x 3 ⁄
4
-in. diameter and 2-in. x 3 ⁄
4
-in. diameter
pipe nipple, coupled to standard 3 ⁄
4
-in. diameter elbows, pro-
vides a straight path down through hole in unit base rail (see
Fig. 12). A trap at least 4-in. deep must be used.
Step 7 — Install Gas Piping — Unit is equipped for
use with natural gas. Installation must conform with local
building codes or, in the absence of local codes, with the
National Fuel Gas Code, ANSI Z223.1.
Install manual gas shutoff valve with a 1 ⁄
8
-in. NPT pres-
sure tap for test gage connection at unit. Field gas piping
must include sediment trap and union. See Fig. 13.
Do not pressure test gas supply while connected to unit.
Always disconnect union before servicing.
Natural gas pressure at unit gas connection must not be
less than 5 in. wg or greater than 13.5 in. wg.
Size gas-supply piping for 0.5-in. wg maximum pressure
drop. Do not use supply pipe smaller than unit gas connec-
tion (
3 ⁄
4
-in. NPT).
PRESSURE
SWITCH
COMBUSTION
FAN HOUSING
HEAT
EXCHANGER
SECTION
Fig. 10 — Combustion Fan Housing Location
3/4" FPT DRAIN
CONNECTION 1-3/8"
DRAIN HOLE
Fig. 11 — Condensate Drain Details
Fig. 12 — Condensate Drain Piping Details
Fig. 13 — Field Gas Piping
8