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11. The furnace has three high temperature limit controls,
which can shut down the burner. They do not shut
down the venter motor.
Unit Shutdown
1. Set the room heating setpoint to lowest setting.
2. Turn off the electrical power supply to the unit.
3. Remove the heat exchanger door on the side of the
unit by removing screws.
4. Move the gas control valve switch to the OFF position.
5. Close manual gas shut off valve external to the unit.
6. Replace the heat exchanger door on the unit.
7. If cooling and/or air circulation will be desired, turn
ON gas control valve switch and the electrical power.
Automatic Reset High Limit Control (LS)
Located in the burner compartment on the heat exchanger,
its sensing element projects through the blower section
bulkhead and senses the temperature at the rear of the
furnace. It will cycle the furnace off if the temperature
exceeds 100°F plus maximum rise.
Auxiliary High Limit Control (ALS)
Located in the blower compartment on the blower housing,
it senses air temperature within the blower compartment
and protects the filters from excessive temperature. It will
shut down the furnace if it senses excessive temperatures.
Elevated temperatures at the control are normally caused
by blower failure. The reason for the shut down should be
determined and repaired prior to resetting.
Manual Reset Flame Rollout Control (RS)
Located in the burner compartment at the top of the burner
assembly, it senses high temperature that could occur if
the heat exchanger tubes were plugged and the flame was
rolling out instead of entering the tubes. It has a manual
push-button reset that cannot be actuated until the limit
control has cooled.
The reason for elevated temperatures at the control should
be determined and repaired prior to resetting this manual
reset control.
WARNING
To avoid property damage, personal injury
or death due to fire or explosion, a qualified
servicer must investigate the reason for the
rollout protection device to open before
manually resetting the rollout protection
device.
Refrigeration System Checks
This unit is equipped with thermal expansion valves.
Ensure the hold-down bolts on the compressor are secure
and have not vibrated loose during shipment. Check
that the vibration grommets have been installed and
visually check all piping for damage and leaks and repair
if necessary. The entire system has been factory charged
and tested, making it unnecessary to field charge. Factory
refrigerant charge is shown on the unit’s nameplate.
To confirm charge levels or, if a leak occurs and charge
needs to be added to the system, it is recommended to
evacuate the system and recharge refrigerant to the unit’s
nameplate specifications. This unit has been rated in the
cooling mode at the AHRI rated conditions of: indoor (80°F
db/67°F wb) and outdoor (95°F db). While operating at this
condition, the superheat should range from 9°F to 11°F for
each refrigeration circuit measured at the suction service
port located near the compressor.
Start-Up Procedure and Checklist
Begin with power turned off at all disconnects.
1. Turn thermostat system switch to “Cool,” and fan
switch to “Auto” and turn temperature setting as high
as it will go.
2.
Inspect all registers and set them to the normal open
position.
3. Turn on the electrical supply at the disconnect.
4. Turn the fan switch to the “ON” position. The blower
should operate after a 7 second delay.
5. Turn the fan switch to “Auto” position. The blower
should stop after a 60 second delay.
6. Slowly lower the cooling temperature until the unit
starts. The compressor, blower and fan should now be
operating. Allow the unit to run 10 minutes, make sure
cool air is being supplied by the unit.
7. Turn the temperature setting to the highest position,
stopping the unit. The indoor blower will continue to
run for 60 seconds.
8. Turn the thermostat system switch to “OFF” and
disconnect all power when servicing the unit.
Refrigeration Sequence Check
1. 24VAC control voltage is provided by the control
transformer to terminal XS. The control voltage is
passed through any installed safety shutdown devices
such as the smoke detector before providing 24VAC
to terminals ES and R.
2. To simulate a mechanical call for cooling lower the
room cooling setpoint to a value below the current
room temperature. The cooling is energized when the
room temperature is above the setpoint for cooling.
3. UNIT WITH ECONOMIZER OPTION:
The
compressor circuit is interlocked through of the
economizer module. If the outdoor air enthalpy
(temperature and humidity) is not suitable for cooling,
the economizer will permit the compressor to be
energized.
4. The blower motor is operated to provide cool supply
air to the space.
5.
Compressor contactor closes its contacts to provide
power to the compressor motor. In addition, the
condenser fan motor is energized through the
compressor contactor.
WARNING
BURN HAZARD!
DO NOT TOUCH! DISCHARGE LINE MAY BE HOT!
Summary of Contents for AHRI 210
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