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Gas Piping
If a flexible gas connector is required or allowed by
the authority that has jurisdiction, black iron pipe shall
be installed at the gas valve and extend outside the
furnace cabinet. The flexible connector can then be
added between the black iron pipe and the gas supply
line.
Gas Supply
1.
This unit is shipped standard for left or right side
installation of gas piping (or top entry in horizontal
applications). Connect the gas supply to the piping
assembly.
2.
When connecting the gas supply piping, consider
factors such as length of run, number of fittings, and
furnace rating to avoid excessive pressure drop.
Table 10 lists recommended pipe sizes for typical
applications.
3.
The gas piping must not run in or through air ducts,
clothes chutes, gas vents or chimneys, dumb waiters,
or elevator shafts.
4.
The piping should be sloped 1/4 inch (6.4 mm) per
15 feet (4.57 m) upward toward the meter from the
furnace. The piping must be supported at proper
intervals [every 8 to 10 feet (2.44 to 3.01 m)] with
suitable hangers or straps. Install a drip leg in vertical
pipe runs to the unit.
5.
A 1/8" N.P.T. plugged tap or pressure post is located
on the gas valve to facilitate test gauge connection.
See Figure 19.
6.
In some localities, codes may require the installation
of a manual main shut off valve and union (furnished
by the installer) external to the unit. The union must be
of the ground joint type.
IMPORTANT
Compounds used on threaded joints of gas piping must
be resistant to the actions of liquified petroleum gases.
NOTE: If emergency shutoff is necessary, shut off the
main manual gas valve and disconnect main power to the
furnace. The installer should properly label these devices.
Page 20 of 34
CAUTION
Leak Check
After gas piping is completed, carefully check all piping
connections (factory and field installed) for gas leaks. Use
a leak detecting solution or other preferred means.
NOTE: If emergency shutoff is necessary, shut off the main
manual gas valve and disconnect the main power to the
furnace. The installer should properly label these devices.
Some soaps used for leak detection are corrosive to
certain metals. Carefully rinse piping thoroughly after
leak test has been completed. Do not use matches,
candles, flame or other sources of ignition to check for
gas leaks.
The furnace must be isolated by closing its individual
manual shut-off valve and disconnecting it from the gas
supply system during any pressure testing of the gas
supply system at pressures less than or equal to 1/2 psig
(3.48 kPa, 14 inches w.c.).
When testing pressure of gas lines, gas valve must be
disconnected and isolated. See Figure 19. Gas valves
can be damaged if subjected to pressures greater than
1/2 psig (3.48 kPa, 14 inches w.c.).
Issue 1809
CAUTION
IMPORTANT
Figure 19
507327-01
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