29
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 pip-
ing.
Install a
3
/
4
-in. NPT street elbow (field-supplied) on the thru-base
gas fitting. Attach a
3
/
4
-in. 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. 39).
Fig. 39 — Gas Line Piping (Size 16)
ALL UNITS
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 ser-
vice. 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 munici-
pal codes require that the manual shutoff valve be located up-
stream of the sediment trap. See Fig. 40 and 41 for typical piping
arrangements for gas piping that has been routed through the side-
wall of the curb. See Fig. 42 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.
Fig. 40 — Gas Piping with Thru-Curb Accessory
Fig. 41 — Gas Piping with Thru-Curb Accessory
(Alternate Layout)
Fig. 42 — Gas Piping Thru-Base Connections
When installing the gas supply line, observe local codes pertaining
to gas pipe installations. Refer to the NFPA 54/ANSI Z223.1
NFGC latest edition (in Canada, CAN/CSA B149.1). In the ab-
sence 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 (7 mm in every 5 m) to prevent traps. Grade
all horizontal runs downward to risers. Use risers to con-
nect 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 (1.8 m). 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 liquefied petro-
leum gases as specified by local and/or national codes. If
using PTFE (Teflon
1
) tape, ensure the material is Double
Density type and is labeled for use on gas lines. Apply
tape per manufacturer’s instructions.
3
/
4
-in. NPT
STREET
ELBOW
THRU-BASE
GAS FITTING
GAS
SUPPORT
BRACKET
9” (229 mm) MIN.
UNION
SHUT OFF
VALVE
DRIP
LEG
THRU-CURB ADAPTER
UNIT BASE RAIL
1. Teflon is a registered trademark of DuPont Corporation.
DRIP
LEG
SHUT OFF
VALVE
UNION
THRU-CURB ADAPTER
BURNER
ACCESS
PANEL
9” (229 mm) MIN.
UNIT BASE RAIL
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