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2.
The thermostat wires (R, W, Y, and G) are
securely connected to the correct leads on
the terminal strip of the circuit board.
3.
The gas line service pressure does not
exceed 10.0 in. water column (0.36 psig),
and is not less than 4.5 in. water column
(0.16 psig) for natural gas. For LP gas the
line service pressure must not exceed 14
in. water column (0.51 psig), and must not
be less than 11.0 in. W.C. (0.40 psig).
4.
The roll-out and vent safety manual reset
switches are closed. If necessary, press
the red button to reset a switch. See Figure
30 for location. DO NOT install a jumper
wire across a switch to defeat its function.
If a switch reopens on start-up, DO NOT
reset the switch without identifying and
correcting the fault condition which caused
the switch to trip.
5.
The blower door is in place, closing the door
switch in the line voltage circuit.
6.
The gas line has been purged and all
connections are leak tight.
Start-up Procedures
After all of the above checks have been made:
1.
Set the thermostat to the lowest setting.
2.
Close the disconnect(s) to provide line
voltage to the furnace.
3.
Follow the procedures given on the operat-
ing instruction label attached to the furnace.
4.
Set the thermostat above room tempera-
ture and verify the operating sequence.
(See the Sequence of Operation).
5.
After the furnace has run for approximately
five minutes, set the thermostat below room
temperature and verify steps (9) through
(11) of the Sequence of Operation.
Verifying and Adjusting Firing Rate
The firing rate must be verified for each instal-
lation to prevent over-firing the furnace.
IMPORTANT NOTE:
The firing rate must not exceed the rate
shown on the furnace rating plate. At alti-
tudes above 2000 feet it must not exceed
that on the rating plate less 4% for each 1000
feet.
34
Follow the procedure below to determine the
firing rate.
1.
Shut off all other gas fired appliances.
2.
Start the furnace and allow it to run for at
least three 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 12.
5.
Multiply the gas flow rate in cubic feet per
hour by the heating value of the gas in Btu
per cubic foot to obtain the firing rate in Btu
per hour. Example:
• Time for 1 revolution of a gas meter with
a 1 cubic foot dial = 40 seconds.
• From Table 11 read 90 cubic feet per
hour of gas.
• Heating value of the gas (obtained from
gas supplier) = 1040 Btu per cubic foot.
• Firing rate = 1040 x 90 = 93,600 Btuh.
6.
Adjustments to the firing rate can be made
by adjusting the gas manifold pressure.
See the High Altitude Application section for
additional information of firing rate at eleva-
tions above 2000 ft.
The manifold pressure must be set to the
appropriate value for your installation. Refer to
either Table 7 for natural gas or Table 8 for LP/
propane gas to verify the manifold pressure
setting required for your particular installation.
To adjust the manifold pressure, remove the
regulator cap and turn the adjusting screw
clockwise to increase pressure or counter-
clockwise to reduce pressure.
regulator cap after adjustments are complete.
CAUTION:
!
Do not re-drill the burner orifices. If the
orifice size must be changed, use only
new orifices.
Replace the
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