269326-UIM-A-1106
12 Unitary Products Group
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 17.
IMPORTANT: An accessible manual shutoff valve must be installed
upstream of the furnace gas controls and within 6 feet (1.8 m) of the fur-
nace. Refer to Figures 14, 15, and 16.
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 1/2 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
Figure 5 dimensions.
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. Refer to Table 7 or the instructions in the propane (LP) con-
version kit for the proper gas orifice size.
HIGH ALTITUDE GAS ORIFICE CONVERSION
This furnace is constructed at the factory for natural gas-fired operation
at 0 – 2,000 ft. (0 m – 610 m) above sea level.
The gas orifices on this furnace 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 2,000 ft. (610 m) above sea level on
natural gas or the altitude is greater than 4,000 ft. (1219 m) above sea
level on propane (LP) gas. Refer to Table 7 for the proper gas orifice
size.
The unit may also be converted for altitudes up to 10,000 ft. (3048 m)
on natural and propane (LP) gas with additional derate as shown in
Table 7 or refer to ANSI Z223.1 NFPA 54 National Fuel Gas Code or in
Canada CAN/CGA-B149.1-00 Natural Gas and Propane Installation
Code.
FIGURE 15: Downflow Configuration (50-125 MBH Model Only)
FIGURE 16: Upflow/Horizontal Configuration (150 MBH Model Only)
BLOWER
DOOR
SWITCH
ROLL-OUT
SWITCHES
BURNERS
HOT
SURFACE
IGNITOR
GAS
VALVE
PRESSURE
SWITCH
VENT
VENT PIPE
TRANSITION
GAS
PIPE
3” DIAMETER
VENT PIPE
GAS
SHUT-OFF
VALVE
ROLL-OUT
SWITCH
DIRT LEG
VENT
BLOWER
FURNACE
CONTROL
BLOWER
DOOR
SWITCH
ROLL-OUT
SWITCHES
BURNERS
HOT
SURFACE
IGNITOR
GAS
VALVE
PRESSURE
SWITCH
GAS
PIPE
GAS
SHUT-OFF
VALVE
ROLL-OUT
SWITCH
DIRT
LEG
VENT
BLOWER
FURNACE
CONTROL
FIGURE 17: Gas Piping
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 oper-
ation and/or the valve to leak.
EXTERNAL MANUAL
SHUTOFF VALVE
TO GAS
SUPPLY
TO GAS
SUPPLY
GROUNDED JOINT UNION
MAY BE INSTALLED
INSIDE OR OUTSIDE UNIT.
DRIP
LEG
PROPANE AND HIGH ALTITUDE CONVERSION KITS
It is very important to choose the correct kit and/or gas orifices for the altitude and the type of gas for which the furnace is being installed.
Only use natural gas in furnaces designed for natural gas. Only use propane (LP) gas for furnaces that have been properly converted to use pro-
pane (LP) gas. Do not use this furnace with butane gas.
Incorrect gas orifices or a furnace that has been improperly converted will create an extremely dangerous condition resulting in premature heat
exchanger failure, excessive sooting, high levels of carbon monoxide, personal injury, property damage, a fire hazard and/or death.
High altitude and propane (LP) conversions are required in order for the appliance to satisfactory meet the application.
An authorized distributor or dealer must make all gas conversions.
In Canada, a certified conversion station or other qualified agency, using factory specified and/or approved parts, must perform the conversion.
The installer must take every precaution to insure that the furnace has been converted to the proper gas orifice size when the furnace is installed.
Do not attempt to drill out any orifices to obtain the proper orifice size. Drilling out a gas orifice will cause misalignment of the burner flames,
causing premature heat exchanger burnout, high levels of carbon monoxide, excessive sooting, a fire hazard, personal injury, property damage
and/or death.
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