TROUBLESHOOTING
(Fig. 16 and 17, and Table 14)
When troubleshooting problems with a WSHP, consider the
following:
Thermistor —
A thermistor may be required for single-
phase units where starting the unit is a problem due to low
voltage. See Fig. 16 for thermistor nominal resistance.
Control Sensors —
The control system employs 2 nom-
inal 10,000 ohm thermistors (FP1 and FP2) that are used for
freeze protection. Be sure FP1 is located in the discharge fluid
and FP2 is located in the air discharge. See Fig. 17.
AIR
COIL
AIRFLOW
(°F)
THERMISTOR
CONDENSATE
OVERFLOW
(CO)
LEGEND
COAX — Coaxial Heat Exchanger
Airflow
Refrigerant Liquid Line Flow
AIRFLOW
(°F)
EXPANSION
VALVE
FP2
FP1
LIQUID
LINE
WATER IN
AIR COIL
WATER
FREEZE
COIL
PROTECTION
PROTECTION
Fig. 17 — FP1 and FP2 Thermistor Location
90.0
80.0
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
0.0
20.0
40.0
Fig. 16 — Thermistor Nominal Resistance
COAX
WATER OUT
36
60.0
80.0
100.0
120.0
Temperature (F)
SUCTION
COMPRESSOR
DISCHARGE
140.0