Heat Pump Operation - Daikin DCC Series Installation Instructions Manual

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
H P S -U P
EAT UMP TART P ROCEDURE
9. Check the cooling mode for the heat pump in the same
manner as above. The reversing valve is energized when
the thermostat is placed in the cooling position. A clicking
sound should be noticeable from the reversing valve. By
lowering the temperature setting to call for cooling, the
contractor is energized. The compressor, blower and fan
should then be running. After the cooling mode is checked
out, turn the thermostat system switch to "OFF".
10. Turn the thermostat system switch to "HEAT" and fan
switch to "AUTO".
11. Slowly raise the heating temperature setting. When the
heating first stage makes contact, stop raising the
temperature setting.. The compressor, blower and fan
should now be running with the reversing valve in the de-
energized (heating) position. After giving the unit time to
settle out, make sure the unit is supplying heated air.
12. If the outdoor ambient is above 80°F, the unit may trip on
its high pressure cut out when on heating. The compressor
should stop. The heating cycle must be thoroughly
checked, so postpone the test to another day when
conditions are more suitable but-DO NOT FAIL TO TEST.
If the outdoor ambient is low and the unit operates
properly on the heating cycle, you may check the pressure
cutout operation by blocking off the indoor return air until
the unit trips.
13. If unit operates properly in the heating cycle, raise the
temperature setting until the heating second stage makes
contact. Supplemental resistance heat, if installed should
now come on. Make sure it operates properly.
NOTE: If outdoor thermostats are installed the outdoor
ambient must be below the set point of these thermostats
for the heaters to operate. It may be necessary to jumper
these thermostats to check heater operation if outdoor
ambient is mild.
14. For thermostats with emergency heat switch, return to
step 11. The emergency heat switch is located at the
bottom of the thermostat. Move the switch to emergency
heat. The heat pump will stop, the blower will continue to
run, all heaters will come on and the thermostat
emergency heat light will come on.
15. If checking the unit in the wintertime, when the outdoor
coil is cold enough to actuate the defrost control, observe
at least one defrost cycle to make sure the unit defrosts
completely.
WARNING
.
F S C
INAL YSTEM HECKS
16. 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.
17. Check for air leaks in the ductwork. See Sections on Air
Flow Adjustments.
18. 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.
19. Set the thermostat at the appropriate setting for cooling
and heating or automatic changeover for normal use.
20. Be sure the Owner is instructed on the unit operation, filter,
servicing, correct thermostat operation, etc.
R P
EFRIGERATION ERFORMANCE
Check that compressor RLA corresponds to values shown in Ap-
pendix B. RLA draw can be much lower than values listed at low
load conditions and low ambient condensing temperatures. Val-
ues in Appendix B can slightly exceed at high load conditions and
high ambient condensing temperatures.

HEAT PUMP OPERATION

C C
OOLING YCLE
When the heat pump is in the cooling cycle, it operates exactly as
a Summer Air Conditioner unit. In this mode, all the charts and
data for service that apply to summer air conditioning apply to
the heat pump. Most apply on the heating cycle except that "con-
denser" becomes "evaporator", "evaporator" becomes "con-
denser", "cooling" becomes "heating".
H C
EATING YCLE
The heat pump operates in the heating cycle by redirecting refrig-
erant flow through the refrigerant circuit external to the compres-
sor. This is accomplished with through the reversing valve. Hot dis-
charge vapor from the compressor is directed to the indoor coil
(evaporator on the cooling cycle) where the heat is removed, and
the vapor condenses to liquid. It then goes through the expansion
device to the outdoor coil (condenser on the cooling cycle) where
the liquid is evaporated, and the vapor goes to the compressor.
When the solenoid valve coil is operated either from heating to
cooling or vice versa, the piston in the reversing valve to the low
pressure (high pressure) reverse positions in the reversing valve.
The following figures show a schematic of a heat pump on the
cooling cycle and the heating cycle. In addition to a reversing valve,
a heat pump is equipped with an expansion device and check valve
for the indoor coil, and similar equipment for the outdoor coil. It is
also provided with a defrost control system.
The expansion devices are flowrator distributors and perform the
same function on the heating cycle as on the cooling cycle. The
flowrator distributors also act as check valves to allow for the re-
verse of refrigerant flow.
12
C
HECK