Unit Lockouts - Bosch SM024 Installation, Operation And Maintenance Manual

SM CS Series Heat
Status LED
YELLOW "ALERT" Welded Contactor
FLASH CODE 8 Compressor always
runs
YELLOW "ALERT" Low Voltage
FLASH CODE 9 Control circuit <
17VAC
Problem
NO FLOW
LOW FLOW
HIGH WATER
TEMPERATURE
LOW HEAT OUTPUT

Unit Lockouts

Periodic lockouts almost always are caused by air
or 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, air flow problems or air
temperature problems. Use of the pressure and
temperature charts for the unit may be required to
properly determine the cause.
Revised 11-13
Comfort Alert Module -Flash Codes
Status LED
Description
1. Compressor contactor has failed closed
2. Thermostat demand signal not connected to module
1. Control circuit transformer is overloaded
2. Low line voltage (contact utility if voltage at disconnect
HRP Troubleshooting
Possible Cause
No Power
On/Off Switch Position
Compressor Contactor
Broken or loose wires
Air Lock
Stuck pump shaft/impeller
Defective pump
Kinked or under sized water piping
Water temp limit closed
Scaled or fouled heat exchanger
Status LED Troubleshooting Information Solution
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
Check power supply
Set switch to "ON" position
Engage heat pump contactor
Repair or tighten wires
Purge air from piping system
Remove pump cartridge and clean
Replace pump
Repair kink and check for proper line size
Stuck limit switch
Sensor not attached securely to line
Clean heat exchanger
Troubleshooting | 25
Checks and Corrections
8 733 920 846 (2013/11)