1083288-UIM-A-0114
Johnson Controls Unitary Products
11
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).
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
Figures 13 and 16.
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 fac-
tory-supplied LP conversion kit. Follow the instructions supplied with
the LP kit.
HIGH ALTITUDE GAS ORIFICE CONVERSION
This furnace is constructed at the factory for natural gas-fired operation
at 0 – 7,999 feet (0 – 2,438 m) above sea level.
The manifold pressure must be changed in order to maintain proper
and safe operation when the furnace is installed in a location where the
altitude is greater than 7,999 feet (2,438 m) above sea level. Refer to
Table 5 for proper manifold pressure settings.
HIGH ALTITUDE PRESSURE SWITCH CONVERSION
For installation where the altitude is less than 5,000 feet (1,524m), it is
not required that the pressure switch be changed unless you are in an
area subject to low pressure inversions.
FIGURE 16:
Gas Piping
Upflow
Configuration
Downflow
Configuration
Horizontal
Configuration
External
Manual
Shut-off
Valve
External
Manual
Shut-off
Valve
External Manual
Shut-off Valve
To Gas
Supply
To Gas
Supply
To Gas
Supply
To Gas
Supply
To Gas
Supply
To Gas
Supply
Drip
Leg
Drip
Leg
Drip
Leg
Drip
Leg
Drip Leg
Drip
Leg
Gas
Pipe
Gas
Valve
Gas
Pipe
Gas
Valve
Gas
Pipe
Gas
Valve
Ground
Union
Ground
Union
Ground
Union
Ground
Union
Ground
Union
Ground
Union
NOTE: Ground Union maybe installed inside or outside unit.
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 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.
Table 5:
Nominal Manifold Pressure - High Fire
Gas Heating
Value
(BTU/cu ft.)
Manifold Pressures
Gas Heating
Value
(MJ/cu m)
Manifold Pressures
Altitude (feet)
Altitude (m)
0-7999
8000-8999
9000-9999
0-2437
2438-2742
2743-3048
in. w.c.
in. w.c.
in. w.c.
kPa
kPa
kPa
800
3.5
3.5
3.5
29.8
0.87
0.87
0.87
850
3.5
3.5
3.5
31.7
0.87
0.87
0.87
900
3.5
3.5
3.5
33.5
0.87
0.87
0.87
950
3.5
3.5
3.3
35.4
0.87
0.87
0.81
1000
3.5
3.2
2.9
37.3
0.87
0.80
0.73
1050
3.5
2.9
2.7
39.1
0.87
0.73
0.67
1100
3.2
2.7
2.4
41.0
0.80
0.66
0.61
2500 (LP)
9.8
8.2
7.5
93.2 (LP)
2.44
2.03
1.86
