69
12
Troubleshooting
(continued)
Table 12E (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Water Heater
Interface
FAULT
DESCRIPTION
CORRECTIVE ACTION
Fan High
OR
Fan Speed High
(will require a manual
reset once the condition
has been corrected. Press
the RESET button on the
display to reset.)
The actual fan RPM is 30% higher than
what is being called for.
• Vent/air intake lengths exceed the maximum allowed
lengths. Refer to Section 2 - General Venting for
proper
lengths.
• Check for obstruction or blockage in the vent/air
intake pipes or at terminations.
• Check the wiring connections at the fan and at the
main control board.
• Replace the fan.
• Replace the main control board.
Sensor Open
(will require a manual
reset once the condition
has been corrected. Press
the RESET button on the
display to reset.)
Either the heat exchanger inlet water, heat
exchanger outlet water or tank temperature
sensor has been disconnected.
S1 = Outlet Sensor
S2 = Inlet Sensor
• Check the sensors and their associated wiring.
Repair or replace the sensor or wiring if damaged.
• Measure the resistance of the sensors and compare
the resistance to the tables on page 64 of this
manual.
• Replace the sensor if necessary.
Sensor Shorted
(will require a manual
reset once the condition
has been corrected. Press
the RESET button on the
display to reset.)
Either the heat exchanger inlet water heat
exchanger outlet water or tank temperature
sensor has been shorted.
S1 = Outlet Sensor
S2 = Inlet Sensor
• Check the sensors and their associated wiring.
Repair or replace the sensor or wiring if damaged.
• Measure the resistance of the sensors and compare
the resistance to the tables on page 64 of this
manual.
• Replace the sensor if necessary.
External Limit
Switch
(will retry after 5
minutes. RESET may be
pressed after condition is
corrected.)
An optional remote limit switch is not making.
• Check function of remote devices.
• Check for loose or misplaced jumper if external
limit switch is not installed.
Automatic Reset
High Limit / HEX
Temp Sw
(will require a manual
reset once the condition
has been corrected. Press
the RESET button on the
display to reset.)
Either the automatic reset high limit
(optional), or the O-Temp heat exchanger
switch has opened.
Automatic Reset High Limit:
• 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 5 - System Piping
for the proper piping methods for the Shield water
heater.
• Check 120 VAC to water heater pump motor on a call
for heat. If voltage is not present, check 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.
• Check resistance of water sensors and compare to
Table 12B on page 64 of this manual. Replace
sensor if necessary.
O-TEMP HEX SWITCH
(Applies to the 285-125 --500-125 Models Only):
• Check continuity across two contacts. Wires should
be connected at both poles of the normally closed
switch.
Installation & Service Manual
TM
