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13 Troubleshooting (continued)
Table 13E (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Water Heater
Interface
FAULT DESCRIPTION CORRECTIVE ACTION
Service Blk
While the unit is in Service Mode, the outlet
temperature has exceeded 185°F.
• Establish a draw to remove HW heat from the
water heater.
• Verify that the system is full of water and that all air
has been properly purged from the system.
• Verify that the water heater is piped properly into the
heating system. Refer to Section 6 - System Piping
for the proper piping methods for the Shield water
heater.
• Check 120 VAC to the water heater pump motor on
a call for heat. If voltage is not present, check the
wiring back to the main control board. Replace the
main control board if necessary.
• If 120 VAC is present on a call for heat and the water
heater pump is not operating, replace the pump.
• Verify that the water heater pump is set to the proper
speed or that the water heater pump is the proper
size. Reference Section 6 - System Piping for water
heater pump specifications.
Low 24 VAC
120 VAC input to the main control board has
dropped below 80 VAC.
• Check 120 VAC supply to the transformer.
• Check wiring connections at the low voltage terminal
strip.
• Check the wire size/length to remote devices.
• Replace the transformer.
Watch Dog Error
The main control board has detected an
internal fault.
• Replace the main control board.
Write EEProm
The main control board has detected an
internal fault.
• Replace the main control board.
CRC Parameters
The main control board has detected an
internal fault.
• Replace the main control board.
Installation & Service Manual
TM