Gas Piping; Gas Valve; Left Side Supply Gas Pipe Arrangement - Johnson Controls TM9V C Series Installation Manual

Horizontal filters
Any branch duct (rectangular or round duct) attached to the plenum
must attach to the vertical plenum before the filter. The use of straps or
supports is required to support the weight of the external filter box.
Downflow filters
Downflow furnaces are typically installed with the filters located above
the furnace, extending into the return air plenum or duct. Any branch
duct (rectangular or round duct) attached to the plenum must attach to
the vertical plenum above the filter height.
Filters may be located in the duct system external to the furnace using
an external duct filter box attached to the furnace plenum or at the end
of the duct in a return filter grille. The use of straps or supports is
required to support the weight of the external filter box.
Section IV: Gas piping
Gas safety
DANGER
!
An overpressure protection device, such as a pressure regulator,
must be installed in the gas piping system upstream of the furnace
and must act to limit the downstream pressure to the gas valve so it
does not exceed 0.5 psig [14 in. W.C. (3.48 kPa)]. Pressures exceed-
ing 0.5 psig [14 in. W.C. (3.48 kPa)] at the gas valve causes damage
to the gas valve, resulting in a fire or explosion, or causes damage to
the furnace or some of its components, resulting in property damage
and loss of life.
Important: Plan the gas supply routing before determining the cor-
rect gas pipe entry. Use 90° conventional elbows and short pipe nip-
ples to enter through the cabinet access holes.
Figure 10: Gas valve
Gas piping installation
Important: Ensure that the gas connections have a 1/2 in. National
Pipe Thread (NPT).
Correctly sized wrought iron, approved flexible, or steel pipe must be
used when making gas connections to the unit. Some utility companies
or local codes require pipe sizes larger than the minimum sizes listed in
these instructions and in the codes. The furnace rating plate and the
instructions in this section specify the type of gas approved for this fur-
nace.
Johnson Controls Ducted Systems
For left side supply gas pipe arrangement, two 1/2 in. elbows and two
1/2 in. x 1 1/2 in. pipe nipples must be used. The arrangement shown in
Figure 11 aligns the entrance hole in the furnace casing with the supply
gas pipe. The furnace casing does not support installations completed
using street-elbows.
Figure 11: Left side supply gas pipe arrangement
If local codes allow the use of a flexible gas appliance connection,
always use a new listed connector. Do not use a connector that has
previously serviced another gas appliance. Use only approved gases.
Use a drip leg and ground union as required. See Figure 12.
Important: An accessible manual shutoff valve must be installed
upstream of the furnace gas controls and within 6 ft (1.8 m) of the fur-
nace.
The furnace must be isolated from the gas supply piping system by
closing its individual external manual shutoff valve during any pressure
testing of the gas supply piping system at pressures equal to or less
than 0.5 psig (3.5 kPa).
CAUTION
!
The gas valve body is a very thin casting that cannot take any exter-
nal pressure. Never apply a pipe wrench to the body of the gas valve
when installing piping. A wrench must be placed on the octagon hub
located on the gas inlet side of the valve. Placing a wrench to the
body of the gas valve will damage the valve, causing incorrect opera-
tion or the valve to leak.
Gas piping may be connected from either side of the furnace using any
of the gas pipe entry knockouts on both sides of the furnace. See Fig-
ure 8 and Figure 12.
Gas orifice conversion for propane (LP)
This furnace is constructed at the factory for natural gas-fired operation,
but may be converted to operate on propane (LP) gas by using a
factory-supplied LP conversion kit. Follow the instructions supplied with
the LP kit.
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