Nortek R6GF Series, Руководство по установке

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18
IN
ON
OFF
Inlet
Pressure
Tap
Inlet
Pressure
Tap
Manifold
pressure
Tap
Manifold
pressure
Tap
2-STAGE GAS VALVES
Model VR8205Q2381
Model VR9205Q1028
ON / OFF
Knob
ON / OFF
Switch
HI Input
Adjusting
Screw
Lo Input
Adjusting
Screw
HI Input
Adjusting
Screw
Lo Input
Adjusting
Screw
Figure 8. HI & LO Input Adjusting Screws
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 25)
.
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.
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.
7. Adjust the manifold pressure if necessary. See page 18 .
For additional information about elevations above 2,000 feet,
see
page 15 .
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 (page 16)
for natural gas or
Table 6 (page 16)
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 for adjusting screw
locations.
3. Replace the regulator cap after adjustments are complete.