Bosch TW Series - Unit Lockouts

24 | Troubleshooting TW Series Water to Water
TW Series Water to Water6720220047 (2016/02) Subject to change without prior notice
Unit Lockouts
Periodic lockouts almost always are caused by water
flow problems. The lockout (shutdown) of the unit is a
normal protective measure in the design of the
equipment. If continual lockouts occur call a mechanic
immediately and have them check for: water flow
problems, water temperature problems. Use of the
pressure and temperature charts for the unit may be
required to properly determine the cause
YELLOW "ALERT”
FLASH CODE 6
Open Start Circuit
Current only in run
circuit
1. Run capacitor has failed (may not be bad, verify)
2. Open circuit in compressor start wiring or connections
• Check wiring and connectors between supply and the
compressor "S'" terminal
3. Compressor start winding is damaged
• Check compressor motor winding resistance
YELLOW "ALERT”
FLASH CODE 7
Open Run Circuit
Current only in start
circuit
1. Open circuit in compressor run wiring or connections
• Check wiring and connectors between supply and the
compressor "R” terminal
2. Compressor run winding is damaged
• Check compressor motor winding resistance
YELLOW "ALERT"
FLASH CODE 8
Welded Contactor
Compressor always
runs
1. Compressor contactor has failed closed
2. Thermostat demand signal not connected to module
YELLOW "ALERT"
FLASH CODE 9
Low Voltage Control
circuit < 17VAC
1. Control circuit transformer is overloaded
2. Low line voltage (contact utility if voltage at disconnect is low)
• Check wiring connections Flash Code number
corresponds to a number of LED flashes, followed by a
pause and then repeated. TRIP and ALERT LEDs flashing
at same time means control circuit voltage is too low for
operation
Comfort Alert Module - Flash Codes
Status LED
Status LED
Description
Status LED Troubleshooting Information Solution
HRP Troubleshooting
Problem Possible Cause Checks and Corrections
NO FLOW
LOW FLOW
No Power Check power supply
On/Off Switch Position
Set switch to “ON” position
Compressor Contactor
Engage heat pump contactor
Broken or loose wires
Repair or tighten wires
Air Lock
Purge air from piping system
Stuck pump shaft/impeller
Remove pump cartridge and clean
Defective pump
Replace pump
Kinked or under sized water piping
Repair kink and check for proper line size
HIGH WATER
TEMPERATURE
Water temp limit closed Stuck limit switch
Sensor not attached securely to line
LOW HEAT OUTPUT Scaled or fouled heat exchanger Clean heat exchanger