31
Example
:
• Time for 1 revolution of a gas meter with a 1
cubic ft dial = 40 seconds.
• From Table 9 read 90 cubic ft gas per hr.
• Local heating value of the gas (obtained from
gas supplier) = 1,040 Btu per cubic ft.
• Input rate = 1,040 x 90 = 93,600 Btuh.
5. Multiply the gas fl ow rate in cubic ft per hr by the
heating value of the gas in Btu per cubic ft to obtain
the input rate in Btuh. See example.
6. The manifold pressure must be set to the appropriate
value for each installation by a qualifi ed installer, service
agency or the gas supplier. See step 3 on page 27.
Verifying and Adjusting Temperature Rise
Confi rm the temperature rise through the furnace is
within the limits specifi ed on the furnace rating plate. Any
temperature rise outside the specifi ed limits could result
in premature failure of the heat exchanger.
1. Place thermometers in the return and supply air stream
as close to the furnace as possible. The thermometer
on the supply air side must be shielded from direct
radiation from the heat exchanger to avoid false
readings.
2. Adjust all registers and duct dampers to the desired
position and run the furnace for 10 to 15 minutes before
taking any temperature readings. The temperature
rise is the difference between the supply and return
air temperatures.
For typical duct systems, the temperature rise will fall
within the limits specifi ed on the rating plate with the
blower speed at the factory recommended setting. If the
measured temperature rise is outside the specifi ed limits,
it may be necessary to change the speed of the blower.
NOTE:
Lowering the blower speed will increase the
temperature rise and a higher blower speed will decrease
the temperature rise.
The furnace is equipped with a multi-speed motor. Heating
and cooling speed selection is made by moving the switch
on the integrated control inside of the furnace.
Verifying Burner Operation
CAUTION:
The door over the burners may only be opened
for inspection purposes only. The door must be
installed during unattended operation.
1. Remove the burner compartment door.
2. Set the thermostat 5 degrees above room temperature
and observe the ignition sequence.
START-UP AND ADJUSTMENTS
Pre-Start Check List
Verify the polarity of the connections are correct, the
line voltage power leads are securely connected and
the furnace is properly grounded.
Verify the thermostat wires (
R
,
W
,
Y
, and
G
) are
securely connected to the correct leads on the
terminal strip of the circuit board.
Verify the gas line service pressure does not exceed
10.0 inches of W.C., and is not less than 4.5 inches
W.C. for natural gas. For LP gas the line service
pressure must not exceed 14 in. W.C., and must not
be less than 11.0 in. W.C.
Verify the roll-out and manual reset switch is closed. If
necessary, press the red button to reset a switch.
DO
NOT install a jumper wire across a switch to defeat
its function.
If a switch reopens on startup, DO NOT
reset the switch without identifying and correcting the
fault condition.
Verify the blower door is in place, closing the door
switch in the line voltage circuit.
Verify the gas line has been purged and all connections
are leak free.
Start-up Procedures
Do not perform these steps until all of the checks in the
previous steps have been completed:
1. Set the thermostat to the lowest setting.
2. Turn off all electrical power to the furnace.
3. Follow the Operating Instructions on the label attached
to the furnace.
4. Set the thermostat above room temperature and verify
the Operating Sequence (page 32).
5. After 5 minutes of operation, set the thermostat below
room temperature and verify steps 9 & 10 of the
Operating Sequence.
Verifying and Adjusting Input Rate
IMPORTANT NOTE:
The input rate must not exceed
the rate shown on the furnace rating plate. At altitudes
above 2,000 feet, it must not exceed that on the rating
plate less 4% for each 1,000 feet.
The input rate must be verifi ed for each installation to
prevent over-fi ring of the furnace. To determine the exact
input rate, perform the following procedures:
1. Shut off all other gas fi red appliances.
2. Start the furnace and run it for at least 3 minutes.
3. Measure the time (in seconds) required for the gas
meter to complete one revolution.
4. Convert the time per revolution to cubic feet of gas
per hour using Table 9 (page 40).
