NOTE: Inlet gas pressure must not exceed the maximum value
shown in the Inlet Gas Pressure chart.
Inlet Gas Pressure
The minimum supply pressure should not vary from that shown in
the Inlet Gas Pressure chart, because this could prevent the unit
from having dependable ignition. In addition, gas input to the
burners must not exceed the rated input shown on the rating
plate. Overfiring of the unit could result in premature heat
IMPORTANT: To avoid possible unsatisfactory operation or
equipment damage due to underfiring of equipment, do not
undersize the Natural/propane gas piping from the meter/tank to
the unit. When sizing a trunk line, include all appliances on that
line that could be operated simultaneously.
Natural Gas Connection
Natural Gas Capacity of Pipe in Cu Ft (m
Nominal Black Pipe Size
Length of Pipe—ft
Pressure = 0.50 psig or less and pressure drop of 0.3" W.C. (Based on 0.60 specific gravity gas)
Heating Value of Gas (Btu/Cu Ft)
Refer to the "Proper Piping Practice" illustration for the general
layout at the unit. The following rules apply:
1. Use black iron pipe and fittings for the supply piping. The use
of a flex connector and/or copper piping is permitted as long
as it is in agreement with local codes.
2. Use pipe joint compound on male threads only. Pipe joint
compound must be resistant to the action of the fuel used.
3. Use ground joint unions.
4. Install a drip leg to trap dirt and moisture before it can enter
the gas control valve. The drip leg must be a minimum of 3"
(7.6 cm) long.
5. Use 2 pipe wrenches when making the connection to the gas
control valve to keep the valve from turning.
Minimum: 5.0" W.C.
Maximum: 10.0" W.C.
Minimum: 11.0" W.C.
Maximum: 13.0" W.C.
) of Gas Per Hour (CFH)
Btu/h Unit Input
High Altitude Derate—U.S. Installations Only
IMPORTANT: The gas/electric units naturally derate with
altitude. Do not attempt to increase the firing rate by changing
orifices or increasing the manifold pressure. This can cause poor
combustion and equipment failure. At all altitudes, the manifold
pressure must be within 0.3" W.C. of that listed on the nameplate
for the fuel used. At all altitudes and with either fuel, the air
temperature rise must be within the range listed on the unit
Refer to the installation manual provided with the LP kit for
conversion from Natural gas to propane gas and for altitude
Use HA02 for installations above 2,000 ft (609.6 m).
The rating plate is stamped with the model number, type of gas
and gas input rating. Make sure the unit is equipped to operate
on the type of gas available. The gas line installation must comply
with local codes, or in the absence of local codes, with the latest
edition of the National Fuel Gas Code NFPA 54/ANSI Z223.1.
6. Install a manual shut off valve in a convenient location (within
6 ft [1.8 m] of the unit) between the meter and the unit.
7. Tighten all joints securely.
8. The unit must be connected to the building piping by one of
the following methods:
Rigid metallic pipe and fittings
Semirigid metallic tubing and metallic fittings (aluminum
alloy tubing must not be used in exterior locations)
Listed gas appliance connectors used in accordance with
the terms of their listing that are completely in the same
room as the equipment
The connector or tubing must be protected against
physical and thermal damage. Aluminum alloy tubing and
connectors must be coated to avoid external corrosion
when in contact with masonry, plaster or insulation or are
subject to repeated wettings by liquids (water—not
rainwater, detergents or sewage).