Page 8
Connect Gas Piping (Gas Units)
Before connecting field-provided piping, check with gas
company or authorities having jurisdiction for local code
requirements. When installing gas supply piping, length
of run from gas meter must be considered in determining
pipe size for 0.5” w.c. (.12kPa) maximum pressure drop.
Do not use supply pipe smaller than unit gas connection.
For natural gas units, operating pressure at the unit gas
connection must be a minimum of 4.7” w.c. (1.19kPa)
and a maximum of 10.5” (2.60kPa) w.c. For LP/propane
gas units, operating pressure at the unit gas connection
must be a minimum of 11” w.c. (2.74kPa) and a maximum
of 13.0” w.c. (3.23kPa).
When making piping connections a drip leg should be
installed on vertical pipe runs to serve as a trap for
sediment or condensate. A 1/8” N.P.T. plugged tap is
located on gas valve for test gauge connection. Refer to
Heating Start-Up section for tap location. Install a ground
joint union between the gas control manifold and the main
manual shut-off valve. See figure 8 for gas supply piping
entering outside the unit. Figure 9 shows bottom gas entry
piping through the curb. Figure 10 shows bottom gas
entry piping through the unit.
Compounds used on threaded joints of gas piping shall be
resistant to the action of liquified petroleum gases.
FIGURE 8
TO GAS
SUPPLY
MANUAL MAIN
SHUT-OFF VALVE
GAS PIPING
SUPPORT
GROUND
JOINT UNION
(REFER TO
LOCAL CODES)
DRIP LEG
OUTSIDE OF UNIT GAS PIPE CONNECTION
TO GAS
VALVE
DRIP LEG
MANUAL MAIN
SHUT-OFF VALVE
GROUND
JOINT UNION
FIGURE 9
BOTTOM ENTRY GAS PIPING
THROUGH THE CURB
4” NIPPLE
TO GAS
SUPPLY
TO GAS
VALVE
ALL ELBOWS ARE 3/4”
5” NIPPLE
ROOF
MOUNTING
FRAME
4” NIPPLE
MULLION BETWEEN
HEAT AND COMPRES
SOR SECTIONS
3” NIPPLE
3-1/2” NIPPLE
4” NIPPLE
7-1/2” NIPPLE
10” NIPPLE
GROMMET
GROMMET
FIGURE 10
BOTTOM GAS ENTRY
THROUGH THE UNIT
DRIP LEG
MANUAL MAIN
SHUT-OFF VALVE
GROUND
JOINT UNION
4” NIPPLE
TO GAS
SUPPLY
TO GAS
VALVE
ALL ELBOWS ARE 3/4”
5” NIPPLE
ROOF MOUNTING
FRAME
4” NIPPLE
MULLION BETWEEN
HEAT AND COMPRES
SOR SECTIONS
3” NIPPLE
3-1/2” NIPPLE
7-1/2” NIPPLE
GROMMET
4” NIPPLE
10” NIPPLE
7”
NIPPLE
ALTERNATE
KNOCKOUTS
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