Amana GUIS Installation Instructions Manual page 23

Two-stage gas-fired warm air furnace
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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.
5. Repeat #1 through #3 on high stage (2nd stage).
6. Turn ON gas and relight appliances turned off in step 1.
Ensure all the appliances are functioning properly and
that all pilot burners are operating.
TEMPERATURE RISE
Air temperature rise is the temperature difference between
supply and return air. The proper amount of temperature
rise is usually obtained when the unit is operated at the rated
input with the “as shipped” blower speed. If the correct
amount of temperature rise is not obtained, it may be
necessary to change the blower speed.
An incorrect temperature rise can cause condensing in or
overheating of the heat exchanger. Determine and adjust
the temperature rise as follows. The temperature rise must
be within the range specified on the rating plate or Specifi-
cation sheet.
1. Operate furnace with burners firing approximately 15
minutes. Ensure all registers are open and all duct
dampers are in their final (fully or partially open) posi-
tion.
2. Place thermometers in the return and supply ducts as
close to the furnace as possible. Thermometers must
not be influenced by radiant heat by being able to “see”
the heat exchanger.
3. Subtract the return air temperature from the supply air
temperature to determine the air temperature rise.
Allow adequate time for thermometer readings to sta-
bilize.
4. Adjust temperature rise by adjusting the circulator
blower speed. Increase blower speed to reduce tem-
perature rise. Decrease blower speed to increase tem-
perature rise. Refer to the following section for speed
CIRCULATOR BLOWER SPEEDS
WARNING
To avoid death or personal injury due to
electrical shock, turn off power to the
furnace before changing speed taps.
All furnaces ship at high speed for cooling and the speeds
listed in Specification Sheet for heating. These speeds
should be adjusted by the installer to match the job require-
ments. See Specification Sheet for details.
Connect the correct motor leads to the COOL, HEAT LO,
HEAT HI, and PARK terminals. If high heating speed will
equal cooling speed, use the jumper wire provided. All
unused motor leads that are not connected to “PARK”
terminals on the control must be taped to prevent shorts.
Page 23

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