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Figure 40. Condensate Trap with Optional Overflow
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.
Do not exceed 600 in.-lbs. (50 ft.-lbs.) torque when
attaching the gas piping to the gas valve.
1.
Gas piping may be routed into the unit through either
the left or right hand side in upflow applications, and
either the top or bottom in horizontal applications.
Supply piping enters into the gas valve from the side
of the valve as shown in Figure 42 and Figure 43.
2.
When connecting gas supply, factors such as length
of run, number of fittings and furnace rating must be
considered to avoid excessive pressure drop. Table 8
lists recommended pipe sizes for typical applications.
NOTE: Use two wrenches when connecting gas piping
to avoid transferring torque to the manifold.
3.
Gas piping must not run in or through air ducts,
clothes chutes, chimneys or gas vents, dumb waiters
or elevator shafts. Center gas line through piping hole.
Gas line should not touch side of unit. See Figure 42
and Figure 43.
507028-03
Switch
CAUTION
WARNING
4.
Piping should be sloped 1/4 " per 15 feet (6 mm per 5.6
m) upward toward the gas meter from the furnace. The
piping must be supported at proper intervals, every 8
to 10 feet (2.44 to 3.05 m), using suitable hangers or
straps. Install a drip leg in vertical pipe runs to serve as
a trap for sediment or condensate.
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 41.
6.
In some localities, codes may require installation of a
manual main shut off valve and union (furnished by
installer) external to the unit. Union must be of the
ground joint type.
Compounds used on threaded joints of gas piping must
be resistant to the actions of liquified petroleum gases.
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. Do not
test with open flame.
The furnace must be isolated from the gas supply system
by closing its individual manual shut-off valve during any
pressure testing of the gas supply system at pressures
more than or equal to 1/2 psig (3.48 kPa, 14 inches w.c.).
When testing gas lines using pressures in excess of 1/2
psig (3.48kPa), gas valve must be disconnected and
isolated. See Figure 35. Gas valves can be damaged if
subjected to pressures greater than 1/2 psig (3.48 kPa).
Issue 1809
WARNING
Figure 41.
IMPORTANT
Page 27 of 66
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