189
Clearance Requirements for Outdoor Installations
Observe the following additional requirements for outdoor
installations:
• Provide at least 6 feet clearance to side of the unit, where
the combustion air inlet or vent (flue) gas discharge is lo
-
cated, from walls, parapets or adjacent buildings or equip
-
ment.
• Unit must be installed with combustion air openings locat
-
ed at least one (1) ft above the average snow depth for the
location.
• Do not locate unit near building ventilators or exhausts, or
areas where corrosive chemical vapors can be drawn into
combustion air supply.
• Do not install units in locations where flue products can be
drawn in the adjacent building openings such as windows,
fresh air intakes, etc.
• Be sure that vent discharge for flue gases is directed away
from combustion air inlet and located to prevent flue prod
-
ucts from being drawn into combustion air supply. Burner
performance can be adversely affected by recirculation of
flue products.
• Combustion air inlet and flue gas outlet must be located in
the same pressure zone to minimize effects of wind on
burner and heater performance.
Clearance Requirements for Indoor Installations
Observe the following additional requirements for indoor
installations:
• Locate unit to ensure an adequate supply of fresh air to re
-
place air used in the combustion and ventilation process.
• When locating units, it is important to consider that ex
-
haust vent piping must connected to the outside atmo
-
sphere. Location should minimize the number of elbows or
turns in vent piping.
GAS SUPPLY, PIPING, AND CONNECTIONS
Installation of piping must conform with local building codes and
ordinances, or in the absence of local codes with ANSI Z223.1,
the National Fuel Gas Code. In Canada, installation must be in
accordance with CAN/CGA-B149.1 for natural gas and B149.2
for propane units.
Use a pipe sealant resistant to LP gases on gas supply connections
to heater. Gas piping must be sized for the total Btu input of all
furnaces or units serviced by a single supply.
Properly support gas valve with back-up wrench during supply
pipe installation to prevent loosening valve or damage to burner
assembly or manifold.
Gas piping must be sized for the total Btu input of all units
(heaters) serviced by a single supply. A 2-in. NPT main gas header
is provided as standard.
A service regulator must be provided to provide gas to the heater
assembly at the proper pressure. Verify that the regulator installed
is sized and properly orificed for total input of all heaters.
A drip leg (sediment trap) and a manual shut-off valve must be
provided immediately upstream of the gas control on the heating
unit. To facilitate servicing of unit, installation of a union is
recommended. See Fig. 149.
Individual furnaces require a minimum inlet gas pressure as
shown in Table 41.
Pressure Testing
A
1
/
8
in. NPT tap is provided on the inlet side of the gas valve to
the heater. See Fig. 150-152. A fitting suitable for connection to a
pressure gage capable of measuring gas pressure should be
connected to each heater serviced by a single regulator so that gas
pressure at each heater can be measured with all heaters in
operation.
Pressure/leak test all connections prior to putting unit in service.
The furnace gas piping was leak-tested prior to shipping.
However, during shipping and installation connections may have
loosened. Check for leaks using a soap solution and correct any
leaks before placing furnace in operation.
VENTING
Gas furnaces must be connected to a properly designed venting
system to convey flue gases away from the heating system or out
-
side of the heated space. See the section Installation Requirements
on page 187 for reference to applicable codes and standards. The
rack assembly requires a special venting system.
Venting for Outdoor Installations
For outdoor applications, a vent riser kit is available. See Fig. 155.
In outdoor installations where the flue riser kit is not used, the
venting system must be properly designed for the specific applica
-
tion by a manufacturer/provider of the listed type of venting sys
-
tems. The connection from furnace-induced draft fans to round
vent pipe requires custom adapters to ensure leak-free joints. Con
-
tact a venting system manufacturer for availability, if the venting
system was not included with the heating system.
Fig. 155 —
Outdoor Venting with Flue Riser Kit
Venting for Indoor Installations
For all indoor installations, a listed venting system must be proper
-
ly designed for the specific application. A factory vent riser kit is
available. See Fig. 156 for an example.
For indoor installations where the factory flue riser kit is not used,
the venting system must be properly designed for the specific ap
-
plication by a manufacturer/provider of the listed type of venting
systems. Connection from furnace-induced draft fans to round
IMPORTANT: Gas pressure to appliance controls must never
exceed 13.5 in. wg (
1
/
2
psig).
IMPORTANT: When pressure testing at
1
/
2
psig or less, close
the manual shut-off valve on the appliance before testing. When
pressure testing the gas supply line at
1
/
2
psig or greater, close
the manual shut-off valve and disconnect the heater from supply
line to be tested. Cap or plug the supply line.
WARNING
All field gas piping must be pressure and leak-tested prior
to operation. Never use an open flame to check for leaks.
Personal injury may result. Use a soap solution or other
leak detecting solution.
COMBUSTION
AIR INTAKE
LOUVERS
OPTIONAL
FLUE
RISER
18" MIN ABOVE
TOP OF AHU
CABINET
