Daikin DBG Series Service Instructions Manual page 19

SYSTEM OPERATION
6. Replace the heat exchanger door on the unit.
7. If cooling and/or air circulation will be desired, turn ON
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 Reset 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 opening should be deter-
mined 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.
T
O AVOID PROPERTY DAMAGE
,
FIRE OR EXPLOSION A QUALIFIED SERVICER MUST INVESTIGATE THE
REASON FOR THE ROLLOUT PROTECTION DEVICE TO OPEN BEFORE
MANUALLY RESETTING THE ROLLOUT PROTECTION DEVICE
NORMAL SEQUENCE OF OPERATION
Cooling
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 65 second delay.
WARNING
,
PERSONAL INJURY OR DEATH DUE TO
.
6. Slowly lower the cooling temperature until first stage COOL
(LOW COOL) starts. The blower, both fans, and first stage
compressor should now be operating. Allow the unit to
run 10 minutes, make sure cool air is being supplied by
the unit.
7. Lower the cooling temperature further until second stage
COOL (HIGH COOL) starts. The blower, both fans, and
both compressors should now be operating. Allow the
unit to run 10 minutes, make sure cool air is being supplied
by the unit.
8. Turn the temperature setting to the highest position,
stopping the unit. The indoor blower will continue to run
for 65 seconds.
9. Turn the thermostat system switch to "OFF" and
disconnect all power when servicing the unit.
HIGH VOLTAGE!
D
ISCONNECT ALL POWER BEFORE SERVICING OR
. M
INSTALLING THIS UNIT ULTIPLE POWER SOURCES MAY
. F
BE PRESENT AILURE TO DO SO MAY CAUSE PROPERTY
,
DAMAGE PERSONAL INJURY OR DEATH
Refrigeration Check
The unit is equipped with a thermal expansion valve as a
metering device.
Ensure the hold-down bolts on the compressor are secure
and have not vibrated loose during shipment. Check that
vibration grommets have been installed. Visually check all
piping for damage and leaks; repair if necessary. The entire
system has been factory charged and tested, making it un-
necessary to field charge. Factory charges are 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 recom-
mended to evacuate the system and recharge refrigerate to
unit nameplate specifications. This unit has been rated in the
cooling mode at the AHRI rated conditions of: Indoor (80° db /
67° wb) and outdoor (95° db). While operating at this condi-
tion, the subcooling should range from 12° to 15° F for each
refrigeration circuit, for 15 and 20 ton models. Sucooling for
25 ton models should be from 16° to 19° F for circuit 1, and
from 12° to 15° F for circuit 2.
Final System Checks
1. Check to see if all supply and return air grilles are adjusted
and the air distribution system is balanced for the best
compromise between heating and cooling.
2. Check for air leaks in the ductwork. See Sections on Air
Flow Adjustments.
3. Make sure the unit is free of "rattles", and the tubing in
the unit is free from excessive vibration. Also make sure
tubes or lines are not rubbing against each other or sheet
metal surfaces or edges. If so, correct the trouble.
4. Set the thermostat at the appropriate setting for cooling
and heating or automatic change over for normal use.
WARNING
.
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