24
GAS SUPPLY AND PIPING
WARNING:
All gas piping must conform with local building
codes, or in the absence of local codes, with
the most recent edition of the National Fuel Gas
Code ANSI Z223.1 or (CAN/CGA B149.1 or .2).
Failure to follow all safety warnings could result
in serious injury, death or property damage.
This furnace may be installed for either left or right side gas
entry. When connecting the gas supply, provide clearance
between the gas supply line and the entry hole in the
furnace casing to avoid unwanted noise and/or damage
to the furnace. Typical gas service hookup for upfl ow and
downfl ow furnaces is shown in Figure 36 (page 28). Table
10 (page 40) lists gas fl ow capacities for standard pipe
sizes as a function of length in typical applications based
on nominal pressure drop in the line.
IMPORTANT NOTES:
• Some local regulations require the installation
of a manual main shut-off valve and ground joint
union external to the furnace (Figure 36). The shut-
off valve should be readily accessible for service
and/or emergency use. Consult the local utility or
gas supplier for additional requirements regarding
placement of the manual main gas shut-off.
• Gas piping must never run in or through air ducts,
chimneys, gas vents, or elevator shafts.
• Compounds used on threaded joints of gas piping
must be resistant to the actions of liquefied
petroleum gases.
• The main gas valve and main power disconnect to
the furnace must be properly labeled by the installer
in case emergency shutdown is required.
• Flexible gas connectors are not recommended for
this furnace but may be used if allowed by local
jurisdiction. Only new fl exible connectors may be
used. DO NOT reuse old fl exible gas connectors.
• A drip leg should be installed in the vertical pipe
run to the unit (Figure 36).
Leak Check
WARNING:
FIRE OR EXPLOSION HAZARD
Never test for gas leaks with an open fl ame.
Check all connections using a commercially
available soap solution. A fi re or explosion
may result causing property damage, personal
injury or loss of life. Failure to follow the safety
warnings exactly could result in serious injury,
death or property damage.
All gas pipe connections must be tested for gas leaks
after they’ve been connected to the furnace. This includes
connections at the main gas valve, emergency shutoff
valve and fl exible gas connectors (if applicable). The soap
and water solution can be applied on each joint or union
using a small paintbrush. If any bubbling is observed,
the connection is not sealed adequately and must be
retightened. Repeat the tightening and soap check process
until bubbling ceases.
IMPORTANT NOTE: When pressure testing gas supply
lines at pressures greater than 1/2 psig (14 inch W.C.),
the gas supply piping system must be disconnected
from the furnace to prevent damage to the gas control
valve. If the test pressure is less than or equal to 1/2
psig (14 inch W.C.), close the manual shut-off valve.
High Altitude Application
High altitude conversion with this furnace depends on the
installation altitude and the heating value of the gas. The
installation of this furnace at altitudes above 2,000 feet
must meet the requirements of the National Fuel Gas
Code or local jurisdiction. In Canada, the requirements for
high altitude are different and governed by CGA B149.1.
Please consult your local code authority.
WARNING:
The reduction of input rating necessary for high
altitude installation may only be accomplished
with factory supplied orifi ces. Do not attempt to
drill out orifi ces in the fi eld. Improperly drilled
orifi ces may cause fi re, explosion, carbon
monoxide poisoning, personal injury or death.
This furnace is shipped from the factory with orifi ces and
gas regulator settings for natural gas operation at sea
level altitudes. At 2000 feet, the NFGC requires that this
appliance be derated 4% for each 1000 feet of altitude. For
example, the input needs to be reduced 8% at 2,000 feet,
12% at 3,000 feet and etc. This deration is in reference to
the input rate and gas heating value at sea level.
To derate the furnace requires knowing the heating value of
the gas at the installation site. Heating values at particular
job sites vary for two reasons:
1. The chemical mixture of the gas varies from region
to region and is expressed as the “sea level heating
value”.
2. The heating value varies by altitude. For this reason,
especially in high altitude areas, the local gas utility
specifi es the heating value at the residence’s gas
meter as the “local value”.
For added fl exibility, two tables have been provided for
natural gas installations with high or low heating values at
sea level. Tables 13 and 14 (page 42) contain the manifold
