Sterling MS - Manual (Page 20)

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PILOT ADJUSTMENT
1. Disconnect wire from terminal marked MV at gas valve.
2. Provide call for heat.
3. Pilot adjustment is found on the gas valve. Remove
pilot adjustment cap.
4. Adjust the pilot screw to provide properly sized fl ame.
5. A proper pilot burner fl ame is a soft steady fl ame that
envelopes 3/8 to 1/2" (9.5 to 12.7mm) of the fl ame
sense probe tip.
6. Replace the pilot adjustment cap.
7. Reconnect wire to terminal MV.
PRIMARY AIR SHUTTER ADJUSTMENT
After the unit has been in operation for at least 15
minutes, adjust the primary air fl ow to the burners. Turn
the friction-locked manually rotated air shutters clockwise
to close, counter clockwise to open. For correct air
adjustment, close the air shutter until yellow tips in the
fl ame appear. Then open the air shutter to the point just
beyond the position where yellow tipping disappears.
CONTROLS
(also see the Indoor Duct Furnace Manual):
Primary Limit Control: The primary limit control is a
factory installed component surface mounted in the inlet
airstream at the end of the heat exchanger. When the
temperature reaches the limit setpoint, normally caused
by insuffi cient air throughput, all gas is shutoff. The limit
control has an automatic reset and once the unit has
cooled, it will reset itself. This is a safety control and if
cycling on the primary limit is noted, corrective action must
be taken. See unit wiring diagram for electrical location.
This control must never be bypassed. Upon completion
of unit installation, the primary limit must be checked for
proper operation. This can be accomplished by removing
power to the indoor air blower and a call for heat.
Clogged Filter Switch: (Optional) The clogged filter
switch monitors the pressure differential across the air
fi lters. If this pressure differential becomes too great, the
switch will alert of this condition. At this point the air fi lters
must either be cleaned or replaced. The switch will reset
itself.
Firestat: (Optional) Located in either the return
airstream, the supply airstream, or both, this control
monitors temperatures with setpoints which are fi eld
adjustable. If the temperature exceeds the setpoint,
the control will cease unit operation. To resume unit
operation, a manual reset of this control is required.
Freezestat: (Optional) Located in either the return
airstream, the supply airstream, or both, this control
monitors temperatures with setpoints which are fi eld
adjustable. If the temperature does not exceed the
setpoint, the control will cease unit operation.
V. START UP
Before starting the unit, use the “Installation Check
Sheet” (located at the end of this manual) and read the
Separated Combustion Indoor Duct Furnace Manual
entirely in conjunction with the procedures outlined
below to ensure that the unit is completely and properly
installed and ready for start up.
It is the installer’s responsibility
to check all safety controls! Check and test
the operational functions of all safety devices
supplied with this unit. Failure to do so could
result in unsafe conditions and may result in
death, serious injury or property damage.
1. Inspect all wiring connections; connections should
be clean and tight. Trace circuits to insure that
actual wiring agrees with the “as wired” diagrams
provided with the unit. Information in the wiring
diagram title block should match the data appearing
on the unit nameplate.
2. Lubricate all electrical motors according to the
manufacturer’s recommendations.
3. Verify that the system switch is in the OFF position.
4. Check unit supply voltage to ensure that it is within
the utilization range.
5. Inspect the interior of the unit; remove any debris or
tools which may be present.
Starting Unit in Heating Mode
1. Close the unit disconnect switch which provides
power to the unit.
High voltage is present in some
areas of the unit (primarily the main electrical
cabinet) with the unit disconnect switch closed.
Failure to exercise caution when working in the
presence of energized electrical components
may result in injury or death from electrical
shock.
2. Set the thermostat/switching subbase as indicated
below: a. position the heating system switch at either
HEAT or AUTO; b. set the fan switch to AUTO.
3. Place the system switch in the ON position. With the
thermostat calling for heat, unit operation is automatic.