Lennox LS25 Series, Руководство по установке

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Page 23
Limit Control Switch
The limit control switch(es) is factory-set and is not
field-adjustable.
Louver Vane Adjustment
Rotate louver vanes to direct airflow upward, downward,
straight, or any combination of these directions.
Flame Rollout Switch
This normally closed switch opens on a temperature rise.
See the parts arrangement for location. These switches
are not adjustable.
Service
CAUTION
Turn off gas and electrical power to unit before performing
any maintenance or service operations on this unit.
Remember to follow lighting instructions when putting
unit back into operation after service or maintenance.
The unit heater and vent system shall be inspected once
a year by a licensed professional service technician, or
equivalent.
BURNERS
1 - Periodically examine burner flames for proper
appearance during the heating season.
2 - Before each heating season examine the burners for
any deposits or blockage that may have occurred.
3 - Clean burners as follows:
a. Turn off both electrical and gas supplies to unit.
b. Disconnect gas supply piping, high tension and
sensor leads. Remove gas manifold. Remove
burner box top. Remove burner cluster assembly.
c. Clean burners as necessary. Make sure that
burner heads line up properly to ensure flame
crossover. Check spark gap on electrode and
adjust if required. The gap should be between
0.110” and 0.140” (3mm to 4mm). The gap may
be checked with appropriately sized twist drills or
feeler gauges.
d. Reinstall burner cluster assembly, burner box
top, gas manifold, high tension and sensor leads.
Reconnect gas supply piping.
e. Restore electrical power and gas supply. Follow
lighting instructions to light unit. Check burner
flame.
Combustion Air Pressure Switch
This pressure switch checks for proper combustion air
inducer operation before allowing an ignition trial. The
switch is factory-set. No field adjustment is necessary. For
high altitude applications, see the Engineering Handbook.
For White Rodgers 36H valve (Figure 12), supply pressure is
accessed by removing 1/8” hex screw. Remove the 1/8” hex
screw and install a 1/8” fitting with hose barb. Connect tubing
from the barbed fitting and route to measuring device to measure
supply pressure.
3 – Open manual main supply valve.
4 - Ignite unit and let run for 5 minutes to allow for steady state
conditions.
5 - After allowing unit to stabilize for 5 minutes, record supply
pressure.
NOTE - On multiple unit installations, each unit should be
checked separately, with and without other units operating. Sup -
ply pressures on both single and multiple unit installations must
fall within range listed on the rating plate.
6 – Shut unit off and remove measuring device, tubing,
or fittings, as soon as, an accurate reading has been
obtained.
For White Rodgers 36G valves (Figure 13), turn the manifold
3/32” hex screw one revolution back into the gas valve.
For White Rodgers 36H valves (Figure 12), remove manifold
barbed fitting and reinstall the 1/8” hex screw.
Manifold Pressure Measurement
NOTE - Pressure test adapter kit (21U27) is available from Len -
nox to facilitate manifold pressure measurement.
To correctly measure total manifold pressure, the pressure be-
tween the positive gas manifold and the negative burner box
must be considered.
NOTE- Total manifold pressure is the sum of the positive “+” and
negative “-” sides of the manifold pressure.
1 - Connect the test gauge positive side “+“ to manifold pressure
tap on gas valve as noted below for the specific gas valve.
For White Rodgers 36G valves (Figure 13) manifold pressure,
back out the 3/32” hex screw one turn, connect a piece of 5/16”
tubing and connect to the “+” side of the measuring device.
For White Rodgers 36H valves (Figure 12) manifold pressure,
remove the 1/8” hex screw, install 1/8” fitting with hose barb,
connect hose from barb to “+” side of measuring device.
2 - Tee into the gas valve regulator vent hose and connect to
test gauge negative “-”.
3 - Ignite unit and let run for 5 minutes to allow for steady state
conditions. If unit has 2 heating inputs, start on higher input.
4 - After allowing unit to stabilize for 5 minutes, record manifold
pressure. For natural gas, compare to value given in tables
7 or 8.
5 - If necessary, make adjustments. Figure 12 and 13 show
adjustment screw(s) locations.
6 - Repeat steps 3, 4 and 5 on lower input.
7 - Shut unit off and remove measuring device as soon as an
accurate reading has been obtained.
For White Rodgers 36G valves (Figure 13), turn the manifold
3/32” hex screw one revolution back into the gas valve.
For White Rodgers 36H valves (Figure 12), remove 1/8” fitting
with hose barb and reinstall 1/8” hex screw.
8 - Start unit and perform leak check. Seal leaks if found.