Carrier WeatherMaster 48HC07-12 Installation Instructions Manual page 15

Install a gas supply line that runs to the unit heating section.
Refer to the NFPA 54/NFGC or equivalent code for gas pipe
sizing data. Do not use a pipe smaller than the size specified.
Size the gas supply line to allow for a maximum pressure drop
of 0.5-in. wg (124 Pa) between gas regulator source and unit
gas valve connection when unit is operating at high-fire flow
rate.
The gas supply line can approach the unit in three ways:
horizontally from outside the unit (across the roof), thru-curb/
under unit basepan (accessory kit required) or through unit
basepan (factory option or accessory kit required). Consult ac-
cessory kit installation instructions for details on these installa-
tion methods. Observe clearance to gas line components per
Fig. 15.
9" MINIMUM CLEARANCE
FOR PANEL REMOVAL
MANUAL GAS
SHUTOFF VALVE
BASE UNIT
48" MINIMUM
BASE RAIL
ROOF
CURB
FROM
GAS
METER
LEGEND
NFGC — National Fuel Gas Code
* Field supplied.
NOTE: Follow all local codes.
STEEL PIPE NOMINAL
DIAMETER (in.)
1/2
3/4 or 1
11/4 or larger
Fig. 15 — Gas Piping Guide (with Accessory Thru-
the-Curb Service Connections)
FACTORY OPTION THRU-BASE CONNECTIONS
(GAS CONNECTIONS) — This service connection kit con-
sists of a NPT gas adapter fitting, an electrical bulkhead con-
nector and a / -in. electrical bulkhead connector, all factory-
3
4
installed in the embossed (raised) section of the unit basepan in
the condenser section. See Fig. 16.
BRASS FITTING FOR 3 TO 6 TON UNITS.
Fig. 16 — Thru-Base Connection Fittings
X
GAS
*
REGULATOR
*
DRIP LEG
*
PER NFGC
FIELD-FABRICATED
*
SUPPORT
SPACING OF SUPPORTS X
DIMENSION (ft)
6
8
10
LOW VOLTAGE
CONDUIT
CONNECTOR
HIGH VOLTAGE
CONDUIT
CONNECTOR
The thru-base gas connector has male and female threads.
The male threads protrude above the basepan of the unit; the
female threads protrude below the basepan.
Check tightness of connector lock nuts before connecting
gas piping.
Gas Line — Install a 1
ly) or 3 / -in. (for all other units) NPT street elbow on the thru-
4
base gas fitting. Attach an appropriate size pipe nipple with
minimum length of 16-in. (406 mm) (field-supplied) to the
street elbow and extend it through the access panel at the gas
support bracket. See Fig. 17.
BRASS FITTING
EMBOSSMENT
FOR 3-6 TON UNITS
Fig. 17 — Gas Line Piping
Other hardware required to complete the installation of the
gas supply line will include a manual shutoff valve, a sediment
trap (drip leg) and a ground-joint union. A pressure regulator
valve may also be required (to convert gas pressure from
pounds to inches of pressure). The manual shutoff valve must
be located within 6-ft (1.83 m) of the unit. The union, located
in the final leg entering the unit, must be located at least 9-in.
(230 mm) away from the access panel to permit the panel to be
removed for service. If a regulator valve is installed, it must be
located a minimum of 4-ft (1220 mm) away from the unit's
flue outlet. Some municipal codes require that the manual shut-
off valve be located upstream of the sediment trap. See Fig. 18
and Fig. 19 for typical piping arrangements for gas piping that
has been routed through the sidewall of the curb. See Fig. 20
for typical piping arrangement when thru-base is used. Ensure
that all piping does not block access to the unit's main control
box or limit the required working space in front of the control
box.
Thru-Curb Adapter
Shut Off
Valve
Fig. 18 — Gas Piping with Thru-Curb Accessory
15
/ -in. (08 and 09 size Low Gas units on-
2
SUPPORT
BRACKET
9" (229mm) min
Union
Unit Base Rail
Drip
Leg