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505309-UIM-D-0511
HORIZONTAL APPLICATION
Horizontal Filters
All filters and mounting provision must be field supplied. All installa-
tions must have a filter installed.
Any branch duct (rectangular or round duct) attached to the plenum
must attach to the vertical plenum before the filter. The use of straps
and/or supports is required to support the weight of the external filter
box.
Downflow Filters
Downflow furnaces typically are 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.
Filter(s) 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(s). The use of straps and/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" w.c. (3.48 kPa)]. Pressures exceeding
0.5 psig [14" w.c. (3.48 kPa)] at the gas valve will cause damage to
the gas valve, resulting in a fire or explosion or cause damage to the
furnace or some of its components that will result in property damage
and loss of life.
To Gas
Supply
External
Manual
Shut-off
Valve
Ground
Union
Drip
Leg
Upflow
FIGURE 16: Gas Piping
An accessible manual shutoff valve must be installed upstream of the
furnace gas controls and within 6 feet (1.8 m) of the furnace.
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).
10
To Gas
NOTE: Ground Union maybe installed inside or outside unit.
Supply
Ground
Union
To Gas
Supply
Gas
Valve
Gas
Pipe
Drip
Leg
Ground
Union
Gas
Drip
Pipe
Leg
Downflow
OUTLET
PRESSURE
PORT
INLET
WRENCH
BOSS
INLET
PRESSURE
PORT
ON OFF
SWITCH
FIGURE 15: Gas Valve
Plan your gas supply before determining the correct gas pipe entry.
Use 90-degree service elbow(s), or short nipples and conventional
90-degree elbow(s) to enter through the cabinet access holes.
GAS PIPING INSTALLATION
Properly sized wrought iron, approved flexible or steel pipe must be
used when making gas connections to the unit. If local codes allow the
use of a flexible gas appliance connection, always use a new listed con-
nector. Do not use a connector that has previously serviced another gas
appliance.
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 furnace - only use those approved gases. The instal-
lation of a drip leg and ground union is required. Refer to Figure 16.
External
Manual
Shut-off
To Gas
Valve
Supply
Ground
Union
Gas
Valve
Drip
Leg
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 improper opera-
tion and/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. Refer to
Figure 13.
HIGH STAGE REGULATOR
ADJUSTMENT
LOW STAGE REGULATOR
ADJUSTMENT
Ground
Union
External Manual
Shut-off Valve
Gas
Valve
Gas
Pipe
Ground
Union
Horizontal
Drip
Johnson Controls Unitary Products
VENT
PORT
OUTLET
To Gas
Supply
Drip Leg
To Gas
Supply
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