Gas Adjustments
Natural Gas
1. Adjust the high stage regulator to required manifold
pressure setting.
2. Reinstall high stage cap screw.
3. Recheck manifold pressure setting with cap on.
4. Adjust low stage regulator to required manifold pres-
sure setting.
5. Reinstall low stage cap screw.
6. Make sure furnace operates at the proper manifold
pressure at both high and low stage outputs.
Propane Gas
1. Adjust the low stage regulator to increase low stage
output so furnace will light and carryover.
2. Adjust the high stage regulator to required manifold
pressure setting.
3. Reinstall high stage cap screw.
4. Recheck manifold pressure setting with cap on.
5. Adjust low stage regulator to required manifold pres-
sure setting.
6. Reinstall low stage cap screw.
7. Make sure furnace operates at the proper manifold
pressure at both high and low stage outputs.
Gas Input Rate measurement (Natural Gas Only)
The gas input rate to the furnace must never be greater than
that specified on the unit rating plate. To measure natural
gas input using the gas meter, use the following procedure.
1. Turn OFF the gas supply to all other gas-burning
appliances except the furnace.
2. While the furnace is operating in low stage, time and
record one complete revolution of the smallest gas
meter dial.
3. Calculate the number of seconds per cubic foot (sec/
ft
) of gas being delivered to the furnace. If using a one
3
cubic foot dial, divide the number of seconds recorded
in step 2 by one. If the dial is a two cubic foot dial, divide
the number of seconds recorded in step 2 by two.
4. Calculate the furnace input in BTUs per hour (BTU/hr).
Input equals the sum of the installation’s gas heating
value and a conversion factor (hours to seconds)
divided by the number of seconds per cubic foot. The
measured input must not be greater than the input
indicated on the unit rating plate.
EXAMPLE:
Installation’s gas heating (HTG) value: 1,000 BTU/ft
3
(Obtained from gas supplier)
Installation’s seconds per cubic foot: 34 sec/ ft
3
Conversion Factor (hours to seconds): 3600 sec/hr
Input = (Htg. value x 3600) ÷ seconds per cubic foot
Input = (1,000 BTU/ft
x 3600 sec/hr) ÷ 34 sec/ ft
3
3
Input = 106,000 BTU/hr
This measured input must not be greater than the input
indicated in Specification Sheet.