Bosch TW Series - Unit Troubleshooting

22 | Troubleshooting TW Series Water to Water
TW Series Water to Water6720220047 (2016/02) Subject to change without prior notice
TROUBLESHOOTING
Troubleshooting Information Solution
column may reflect a possible fault that may
be one of, or a combination of causes and
solutions. Check each cause and adopt
“process of elimination” and or verification
of each before making any conclusion.
Unit Troubleshooting
Problem Possible Cause Checks and Correction
ENTIRE UNIT
DOES NOT RUN
Power Supply Off Apply power, close disconnect
Blown Fuse
Replace fuse or reset circuit breaker. Check for correct fuses
Voltage Supply
Low
If voltage is below minimum voltage specified on unit data plate,
contact local power company.
UNIT OFF ON
HIGH PRESSURE
CONTROL
Discharge
pressure too high
In “COOLING” mode: Lack of or inadequate water flow. Entering water
temperature is too warm. Scaled or plugged condenser. In “HEATING”
mode: Lack of or inadequate load side fluid flow.
Refrigerant
charge
The unit is overcharged with refrigerant. Reclaim refrigerant, evacuate
and recharge with factor recommended charge.
High pressure
Check for defective or improperly calibrated high pressure switch.
UNIT OFF ON LOW
PRESSURE
CONTROL
Suction pressure
too low
In “COOLING” mode: Lack of or inadequate Source side fluid. flow.
Entering water temperature is too cold. In “HEATING” mode: Lack of or
inadequate water flow. Entering water temperature is too cold. Scaled
or plugged condenser.
Refrigerant
charge
The unit is low on refrigerant. Check for refrigerant leak, repair,
evacuate and recharge with factory recommended charge.
Low pressure
switch
Check for defective or improperly calibrated low pressure switch.
UNIT SHORT
CYCLES
Unit oversized Recalculate heating and or cooling loads.
Thermostat
Thermostat installed near a supply air grill; relocate thermostat.
Readjust heat anticipator.
Wiring and
controls
Check for defective or improperly calibrated low pressure switch.