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Regulate flow to condenser with a supply line valve. If pump is a
non overloading type, the valve may be fully closed while pump is
running.
For average scale deposit, allow solution to remain in condenser
overnight. For heavy scale deposit, allow 24 hours. Drain con-
denser and flush with clean water. Follow acid manufacturer's
instructions.
Checking System Charge
Units are shipped with full operating charge. If recharging is
necessary:
1.
Insert thermometer bulb in insulating rubber sleeve on liquid
line near filter drier. Use a digital thermometer for all tem-
perature measurements. DO NOT use a mercury or dial-type
thermometer.
2.
Connect pressure gage to discharge line near compressor.
3.
After unit conditions have stabilized, read head pressure on
discharge line gage.
4.
NOTE: Operate unit a minimum of 15 minutes before
checking charge.
5.
From standard field-supplied Pressure-Temperature chart for
R-410A, find equivalent saturated condensing temperature.
6.
Read liquid line temperature on thermometer; then subtract
from saturated condensing temperature. The difference
equals subcooling temperature.
7.
Compare the subcooling temperature with the normal tem-
perature. If the measured liquid line temperature does not
agree with the required liquid line temperature, ADD refrig-
erant to raise the temperature or REMOVE refrigerant
(using standard practices) to lower the temperature (allow a
tolerance of ± 3°F).
Refrigerant Charging
WARNING
To prevent personal injury, wear safety glasses and gloves
when handling refrigerant. Do not overcharge system — this
can cause compressor flooding.
NOTE: Do not vent or depressurize unit refrigerant to atmosphere.
Remove and recover refrigerant following accepted practices.
Air Coil Fan Motor Removal
CAUTION
Before attempting to remove fan motors or motor mounts,
place a piece of plywood over evaporator coils to prevent coil
damage.
Disconnect motor power wires from motor terminals before motor
is removed from unit.
1.
Shut off unit main power supply.
2.
Loosen bolts on mounting bracket and remove inlet ring.
3.
Remove motor.
Slide motor/bracket assembly to extreme right and lift out through
space between fan scroll and side frame. Rest motor on a high
platform such as a step ladder. Do not allow motor to hang by its
power wires.
TROUBLESHOOTING
When troubleshooting problems with a WSHP, consider the
following.
UNIT PROTECTION MODULE (UPM)
Each unit is factory provided with a UPM board that controls the
compressor operation and monitors the safeties. The UPM board
should be one of the first areas to start with troubleshooting an
equipment issue. See Fig. 43.
1
2
3
4
5
17
1
Board Power Indicator
2
UPM Status LED Indicator
Water Coil Freeze Protection Temperature Selection
3
[R30]
4
Air Coil Freeze Protection Temperature Selection
5
UPM Settings
6
Water Coil Freeze Connection
7
Air Coil Freeze Connection
8
LED Status-Diagnostic Connection
9
24VAC Power Input
10
Compressor Contact Output
11
High Pressure Switch Connection
12
Call for Compressor Y1
13
Low Pressure Switch Connection
14
24VAC Power Common
15
Condensate Overflow Sensor
16
Dry Contact
17
UPM Ground Standoff
Fig. 43 — Unit Protection Module (UPM)
Safety controls include the following:
•
High-pressure switch located in the refrigerant discharge
line and wired across the HPC terminals on the UPM.
•
Low-pressure switch located in the unit refrigerant suction
line and wired across terminals LPC1 and LPC2 on the
UPM board.
•
UPM board dry contacts are normally open (NO).
•
Water-side freeze protection sensor, mounted close to con-
densing water coil, monitors refrigerant temperature be-
tween condensing water coil and thermal expansion valve.
If temperature drops below or remains at freeze limit trip
for 30 seconds, the controller will shut down the compres-
sor and enter a soft lockout condition. The default freeze
limit trip is 26°F, however this can be changed to 15°F by
cutting the R30 or Freeze1 resistor located on top of DIP
switch SW1. Refer to Fig. 43, Item 3 for resistor location.
If unit is employing a fresh water system (no anti-freeze
protection), it is extremely important to have the Freeze1
R30 resistor set to 26°F in order to shut down the unit at
the appropriate leaving water temperature and protect heat
pump from freezing if a freeze sensor is included.
55
13
12
15
7
9
11
10
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