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Limit Control Switch
The limit control switch(es) is factory-set and is not
eld-adjustable.
Louver Vane Adjustment
Rotate louver vanes to direct airow upward, downward,
straight, or any combination of these directions. When
30/105 units are is installed in an inverted position, lou-
vers must be removed and rotated 180 degrees as shown
in the installation section.
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 o 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 ames 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 o 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 ame
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
ame.
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 eld adjustment is necessary. For
high altitude applications, see the Engineering Handbook.
For White Rodgers 36H valve (Figure 13), supply pressure is
accessed by removing 1/8” hex screw. Remove the 1/8” hex
screw and install a 1/8” tting with hose barb. Connect tubing
from the barbed tting 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 o and remove measuring device, tubing,
or ttings, as soon as, an accurate reading has been
obtained.
For White Rodgers 36G valves (Figure 14), turn the supply pres-
sure 3/32” hex screw one revolution back into the gas valve.
For White Rodgers 36H valves (Figure 13), remove supply pres-
sure barbed tting and reinstall the 1/8” hex screw.
Manifold Pressure Measurement
1 - Connect the measuring device based upon the type of gas
valve.
For White Rodgers 36G valves (Figure 14) 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 13) manifold pressure,
remove the 1/8” hex screw, install 1/8” tting with hose barb,
connect hose from barb to “+” side of measuring device.
2 - Ignite unit and let run for 5 minutes to allow for steady state
conditions. If unit has 2 heating inputs, start on higher input.
3 - After allowing unit to stabilize for 5 minutes, record manifold
pressure. For natural gas, compare to value given in tables
6 or 7.
4 - If necessary, make adjustments. Figure 13 and 14 show
adjustment screw(s) locations.
5 - Repeat steps 3, 4 and 5 on lower input.
6 - Shut unit o and remove measuring device as soon as an
accurate reading has been obtained.
For White Rodgers 36G valves (Figure 14), turn the manifold
3/32” hex screw one revolution back into the gas valve.
For White Rodgers 36H valves (Figure 13), remove 1/8” tting
with hose barb and reinstall 1/8” hex screw.
7 - Start unit and perform leak check. Seal leaks if found.
Supply Pressure Measurement
1 - Shut o the manual main supply valve (eld
furnished) when installing or removing the measuring
device (Steps 2 and 6).
2 – Connect the measuring device based upon type of
gas valve.
For White Rodgers 36G valve (Figure 14), an inlet post lo-
cated on the gas valve provides access to the supply pres-
sure. Open the inlet port by backing out the 3/32” hex screw
one turn. Connect a piece of tubing over the inlet post and
route to a measuring device to measure supply pressure.
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