Start-Up & Adjustments; Pre-Start Checklist; Start-Up Procedures; Verifying & Adjusting Input Rate - Heat Controller 80+ AFUE Installation Instructions Manual

NOTE: One furnace can be used for one stage of heating
and the other furnace can be used for the second stage of
heating. The installer also has the choice of running one
furnace only or both furnaces. In both cases the blowers
will run at the same time and at the same speeds:
• Single stage heating: The w connection on each furnace
must be connected together and then connected to the
w connection of the thermostat. This will allow both
furnaces to ignite at the same time for one stage heating.
• Two stage heating: The w connection on one furnace
must be connected to the w1 connection of the
thermostat. The w connection of the second furnace
must be connected to the w2 connection of the
thermostat. This will allow one furnace to ignite for one
stage of heating and the second furnace to ignite for
the second stage of heating.
3. Refer to Figure 16 (page 21) for the remaining thermostat
connections. The C connection must be made between
the twinned furnaces to ensure proper performance.
START-UP & 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, & 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 23).
5. After 5 minutes of operation, set the thermostat below
room temperature and verify steps 9 - 10 of the Operating
Sequence.
22
Verifying & Adjusting Input Rate
The input rate must be verified for each installation to
prevent over-firing of the furnace. 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. To determine
the exact input rate, perform the following procedures:
1. Shut off all other gas fired 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 5 (page 31).
5. Multiply the gas flow 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.
Example:
• Time for 1 revolution of a gas meter with a 1 cubic
ft dial = 40 seconds.
• From Table 5 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.
wARNING:
Do not attempt to drill the gas orifices. Use only
factory supplied orifices. Improperly drilled
orifices may cause fire, explosion, carbon
monoxide poisoning, personal injury or death.
6. Obtain the manifold pressure setting required for this
installation by referring to Table 7 (page 32) for Propane
or Tables 9 or 10 for Natural Gas (page 33).
The manifold pressure must be set to the appropriate
value for each installation by a qualified installer,
service agency or the gas supplier.
7. Remove the regulator capscrew (Figure 17, page 23)
from the INLET side of the regulator.
8. Slowly turn the adjustment screw inside the regulator
to obtain the appropriate manifold pressure.
NOTE: Turning the screw clockwise increases the
pressure and turning the screw counter-clockwise
decreases the pressure. To prevent backing the screw
all the way out from the valve, turn the screw slowly.
9. Replace and tighten the regulator capscrew over the
adjustment screw.
Verifying & Adjusting Temperature Rise
After installation of the furnace, confirm the temperature
rise of the furnace is within the limits specified on the rating
plate. Any temperature rise outside the specified limits
could result in premature failure of the heat exchanger.