Installing Your Furnace
20
Start-Up Procedure
WARNING:
Danger of property damage, bodily
injury or loss of life. Liquefied Petroleum (L.P.) Gas
is heavier than air and may settle in any low area,
including open depressions and may remain there
unless area is ventilated. Never attempt start-up of
unit before thoroughly ventilating the area.
Check the furnace operation as outlined in the following
instructions. If any sparking, odors or unusual noises are
encountered, shut off electric power immediately. Recheck for
wiring errors or obstructions in or near fan motor (if equipped).
WARNING:
Natural gas heating value (Btu per
cubic foot) can vary significantly. Therefore, it is
the installer's responsibility to see that Btu/hr. input
to the furnace is adjusted properly. Failure to do so
could
cause
combustion
chamber
failure,
asphyxiation, fire or explosion resulting in damage,
bodily injury or death. Refer to the National Fuel
Gas Code (NFPA 54) to be sure the furnace is
burning fuel at the proper rate.
CHECK GAS INPUT AND PRESSURES
For furnaces located at elevations between sea level and 2,000
feet, the measured input must not be greater than the input shown
on the nameplate of the furnace. For elevations above 2,000 feet,
the measured input must not exceed the input on the nameplate
reduced by 4
percent for each 1,000 feet that the furnace is above
sea level.
Gas supply pressure and manifold pressure with the burner(s)
operating must also be as specified on the nameplate.
Rated input will be obtained on a heating value of 2,500 Btu/hr. for
propane at 10-inches manifold pressure with factory-sized
orifices. If L.P. gas having a different heating value is supplied,
orifices must be changed by a qualified service technician before
the furnace is operated.
CHECK THE MANIFOLD GAS PRESSURE
A tapped opening is provided in the gas valve to facilitate
measuring manifold gas pressure. A water column manometer
having a scale range from 0 to 12-inches of water column should
be used for this measurement. The manifold pressure must be
measured with the burner and pilot operating. Any major changes
in the flow must be made by changing the size of the burner
orifice.
CHECK THE GAS INPUT (NATURAL GAS ONLY)
Under firing could cause inadequate heat, excessive
condensation or ignition problems. Over firing could cause
shooting flame impingement or overheating of the combustion
chamber. Before starting natural gas input check, obtain the
heating value of gas (Btu per cubic foot) at standard conditions
from your local gas supplier.
To measure the input, using the gas meter, proceed as follows:
1.
Turn off gas supply to all other appliances except the
furnace.
2.
With the furnace operating, time the smallest dial on the
meter for one complete revolution. If this is a 2-cubic-foot
dial, divide the seconds by 2. If it is a 1-cubic-foot dial, use
the time in seconds as is. This gives the seconds per cubic
foot of gas being delivered to the furnace.
3.
Assuming natural gas with a heating value of 1,000 Btu per
cubic foot and 34-seconds per cubic foot used as
determined by step (2), then:
Seconds per hour = 3,600
Input = 1,000 x 3,600 / 34 = 106,000 Btu/hr.
This measured input must not be greater than the input
indicated on the nameplate of the furnace.
4.
Relight all other appliances turned off in Step 1 above. Be
sure all pilots are operating.
CHECK THERMOSTAT
Check thermostat operation. When set above room temperature
shown on the thermostat, the main burner should light. Make
certain the thermostat turns off the furnace when the room
temperature reaches the selected setting and starts the furnace
when room temperature falls a few degrees below the thermostat
setting.
Type of Gas
Manifold Pressure, In. W.C.
Natural
4.0
L.P.
10.0
CHECK GAS CONTROL VALVE WIRE CONNECTIONS
