Sterling RT - Manual (Page 17)

17
Method to Check Manifold Pressure
1. Close the manual valve of unit gas valve.
2. Install a 1⁄8 inch pipe connection in the tapped hole
provided in the gas valve body near outlet of the valve.
3. Attach manometer to 1⁄8 inch pipe connection by
means of a rubber hose.
4. Fire unit according to instructions and observe the
pressure and confi rm it matches the unit manifold
pressure from the unit rating plate.
5. Small variations in the manifold pressure can be
made by means of the gas valve pressure regulator.
Remove pressure regulator cap and turn regulator
clockwise to increase pressure or counter-clockwise
to decrease pressure.
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 inch (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
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.
Draftor End Switch: This switch is located at the end of
the draftor motor and is integral to the motor. The switch,
which is normally open, will close when draftor motor
attains the minimum speed for proper combustion allowing
main burner operation. The pilot burner will light without
a proven draftor end switch. See unit wiring diagram for
electrical location.
Clogged Filter Switch: (Optional) The clogged fi lter
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
Outdoor 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.
Installer’s responsibility! All
safety controls must be checked! 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.