Lochinvar Shield SNR150-100 - Manual (Page 70)

70
13
Troubleshooting
Table 13E (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Water Heater
Interface
FAULT DESCRIPTION CORRECTIVE ACTION
Automatic Reset
High Limit / HEX
Temp Sw
(cont’d)
(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.
O-TEMP HEX SWITCH
(Applies to the 285-125 --500-125 Models Only):
• Inspect the back of the inner combustion chamber
at burner level for refractory breakdown / missing.
Replace refractory if no damage to the heat
exchanger as a result of the burner, otherwise,
replace the heat exchanger.
• Faulty O-Temp HEX Switch. Replace switch.
Temp O/Shoot
The flue temperature has exceeded the set
parameters for the water heater.
• Inspect the heat exchanger. Reference page 61 of
this manual for the procedure on how to clean the
flue side of the heat exchanger.
• Inspect the flue sensor and associated wiring.
Measure the resistance of the flue sensor and
compare to Table 13C on page 64 of this manual.
Replace the sensor if necessary.
• Verify that the vent/air intake pipes are properly
installed and that there are no obstructions.
• Replace the main control board.
Scaling has reduced water flow. • Deliming may be required.
The temperature rise across the heat
exchanger has exceeded the set parameters
for 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 for 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 pump is the proper size.
Reference Section 6 - System Piping for water heater
pump
specifications.
Heat exchanger outlet water temperature
has exceeded the maximum outlet water
temperature.
• 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 for 120 VAC to the 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.
• Replace the main control board.
Installation & Service Manual TM