Daikin DAR09, Инструкция по эксплуатации

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SERVICING
S-106 OVERFEEDING
Overfeeding by the expansion valve results in high suction
pressure, cold suction line, and possible liquid slugging of the
compressor.
If these symptoms are observed:
1. Check for an overcharged unit by referring to the cooling
performance charts in the servicing section.
2. Check the operation of the power element in the valve as
explained in S-110 Checking Expansion Valve Operation.
3. Check for restricted or plugged equalizer tube.
S-107 UNDERFEEDING
Underfeeding by the expansion valve results in low system ca -
pacity and low suction pressures.
If these symptoms are observed:
1. Check for a restricted liquid line or drier. A restriction will be
indicated by a temperature drop across the drier.
2. Check the operation of the power element of the valve as
described in S-110 Checking Expansion Valve Operation.
S-108 SUPERHEAT
The expansion valves are factory adjusted to maintain 8 to
12 degrees superheat of the suction gas. Before checking the
superheat or replacing the valve, perform all the procedures
outlined under Air Flow, Refrigerant Charge, Expansion Valve -
Overfeeding, Underfeeding. These are the most common causes
for evaporator malfunction.
CHECKING SUPERHEAT
Refrigerant gas is considered superheated when its temperature
is higher than the saturation temperature corresponding to its
pressure. The degree of superheat equals the degrees of tem -
perature increase above the saturation temperature at existing
pressure. See Temperature - Pressure Chart on following pages.
CAUTION
To prevent personal injury, carefully connect and
disconnect manifold gauge hoses. Escaping liquid
refrigerant can cause burns. Do not vent refrigerant
to atmosphere. Recover during system repair
or final unit disposal.
1. Run system at least 10 minutes to allow pressure to stabilize.
2. For best results, temporarily install a thermometer on the
liquid line at the liquid line service valve and 4-6” from the
compressor on the suction line. Ensure the thermometer
makes adequate contact and is insulated for best possible
readings. Use liquid line temperature to determine sub-cool -
ing and vapor temperature to determine superheat.
NOTE: An optional method is to locate the thermometer at the
suction line service valve. Ensure the thermometer makes ade -
quate contact and is insulated for best possible readings.
3. Refer to the superheat table provided for proper system
superheat. Add charge to lower superheat or recover charge
to raise superheat.
Superheat Formula = Suct. Line Temp. - Sat. Suct. Temp.
EXAMPLE:
a. Suction Pressure = 143
b. Corresponding Temp. °F. = 50
c. Thermometer on Suction Line = 61°F.
To obtain the degrees temperature of superheat, subtract 50.0
from 61.0°F.
The difference is 11° Superheat. The 11° Superheat would fall in
the ± range of allowable superheat.
SUPERHEAT AND SUBCOOLING ADJUSTMENT ON TXV APPLICA-
TIONS
NOTE: Units mached with indoor coils equipped with nonadjust -
able TXV should be charged by subcooling only.
1. Run system at least 10 minutes to allow pressure to stabilize.
2. For best results, temporarily install a thermometer on the
liquid line at the liquid line service valve and 4-6” from the
compressor on the suction line. Ensure the thermometer
makes adequate contact and is insulated for best possible
readings. Use liquid line temperature to determine sub-cool -
ing and vapor temperature to determine superheat.
NOTE : An optional method is to locate the thermometer
at the suction line service valve. Ensure the thermometer
makes adequate contact and is insulated for best possible
readings.
3. Check subcooling and superheat. Systems with TXV applica -
tion should have a subcooling of 7 to 9 ºF and superheat of 7
to 9 ºF.
a. If subcooling and superheat are low, adjust TXV to 7 to
9 ºF superheat, then check subcooling.
NOTE
: To adjust superheat, turn the valve stem clockwise to
increase and counter clockwise to decrease.
b. If subcooling is low and superheat is high, add charge
to raise subcooling to 7 to 9 ºF then check superheat.
c. If subcooling and superheat are high,
adjust
TXV valve
to 7 to 9 ºF superheat, then check subcooling.
d. If subcooling is high and superheat is low, adjust TXV
valve to 7 to 9 ºF superheat and remove charge to lower the
subcooling to 7 to 9 ºF.
The TXV should
NOT
be adjusted at light load conditions 55º
to 60ºF, under such conditions only the subcooling can be
evaluated. This is because suction pressure is dependent on
the indoor coil match, indoor airflow, and wet bulb tempera -
ture.
NOTE
: Do
NOT
adjust charge based on suction pressure
unless there is a gross undercharge.