Reznor R6GF Unit Installation Manual - Manual (Page 18)

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supply air side must be shielded against direct radiation
from the heat exchanger to avoid false readings.
2. Adjust all registers and duct dampers to the desired
position. Run the unit for 10 to 15 minutes before
taking any temperature readings. The temperature
rise is the difference between the supply and return air
temperatures.
NOTE: For typical duct systems, the temperature rise will
fall within the range specified on the data label (with the
blower speed at the factory recommended setting) shown
in Table 9 (page 25). If the measured temperature rise falls
outside the specified range, it may be necessary to change
the blower speed. Lowering the blower speed increases
the temperature rise and a higher speed decreases the
temperature rise.
The unit is equipped with a variable speed motor. Heating
and cooling speed selection is made by changing the tap
settings on the ignition control board located in the unit
control box. Refer to Configuring the Variable Speed Blower
Section (page 12) for additional information.
The Variable Speed Blower (VSB) is designed with built
in delay profiles for start up and shut down of the system.
Refer to the Operating Sequence section (page 19) for
more details.
Verifying & Adjusting Firing Rate
CAUTION:
Do not re-drill the burner orifices. If the orifice
size must be changed, use only new orifices.
The firing rate must be verified for each installation to
prevent over-firing of the furnace. The firing rate must
not exceed the rate shown on the unit data label.
To
determine the firing rate, follow the steps below:
1. Obtain the gas heating value (HHV) from the gas supplier.
2. Shut off all other gas fired appliances.
3. Start the unit in heating mode and allow it to run for at
least 3 minutes.
4. Measure the time (in seconds) required for the gas
meter to complete one revolution.
5. Convert the time per revolution to cubic feet of gas per
hour using Table 13 (page 26).
6. 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. See Example.
7. Adjust the manifold pressure if necessary. See Manifold
Pressure Adjustment instructions. For additional
information about elevations above 2,000 feet, see
page 16.
Verifying Over-Temperature Limit Control
Operation
1. Verify the louvered control access panel is in place and
that there is power to the unit.
2. Block the return airflow to the unit by installing a close-
off plate in place of or upstream of the filter.
3. Set the thermostat above room temperature and verify
the units operating sequence (page 19).
NOTE: The over-temperature limit control should turn
off the gas valve within approximately four minutes
(exact time depends on the efficiency of the close-off
when blocking the return air). The circulating air and
combustion blowers should continue to run when the
over-temperature limit control switch opens.
4. Remove the close-off plate immediately after the over-
temperature limit control opens. If the unit operates
for more than four minutes with no return air, set the
thermostat below room temperature, shut off power to
the unit, and replace the over-temperature limit control.
Verifying Burner Operation
WARNING:
Uninsulated live components are exposed when
louvered control access panel is removed.
1. Remove the louvered control access panel and verify
there is power to the unit.
2. Set thermostat above room temperature and observe
the ignition sequence. NOTE: The burner flame should
carry over immediately between all burners without
lifting off, curling, or floating. The flames should be blue,
without yellow tips. Make sure the flame is drawn into
the center of the heat exchanger tube. In a properly
adjusted burner assembly, the flame bends down and
to the right at the end of the heat exchanger tube. The
end of the flame will be out of sight around the bend.
3. After validating flame characteristics, set the thermostat
below room temperature and verify the burner flame
extinguishes completely.
Manifold Pressure Adjustment
The manifold pressure must be set to the appropriate
value for your installation. To adjust the manifold pressure:
1. Obtain the required manifold pressure setting. Use
Table 5 for natural gas or Table 6 for LP/propane gas.
NOTE: The values listed in the tables are based on
sea level values. At higher altitudes, the heating value
of gas is lower than the sea level heating value.
2. Remove the regulator cap. Turn the high fire
adjusting screw clockwise to increase the pressure or
counterclockwise to reduce the pressure. See Figure
8 (page 23) for adjusting screw locations.
3. Replace the regulator cap after adjustments are
complete.
Example:
• Time for 1 revolution of a gas meter with a 1 cubic
foot dial = 40 seconds.
• From Table 13, read 90 cubic feet gas per hour.
• Local heating value of the gas (obtained from gas
supplier) = 1,040 Btu per cubic foot.
• Input rate = 1,040 x 90 = 93,600 Btuh.