Lochinvar Shield SNR150-100 Installation & Service Manual page 70

12
Troubleshooting
Table 12E (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Water Heater
Interface
FAULT
Automatic Reset
High Limit / HEX
Temp Sw
(cont'd)
Either the automatic reset high limit
(optional), or the O-Temp heat exchanger
(will require a manual
switch has opened.
reset once the condition
has been corrected. Press
the RESET button on the
display to reset.)
The flue temperature has exceeded the set
parameters for the water heater.
Scaling has reduced water flow.
The temperature rise across the heat
exchanger has exceeded the set parameters
for the water heater.
Temp O/Shoot
Heat exchanger outlet water temperature
has exceeded the maximum outlet water
temperature.
70
DESCRIPTION
Installation & Service Manual
TM
CORRECTIVE ACTION
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.
• 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 12C 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.
• Deliming may be required.
• 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 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 5 - System Piping for water heater
pump specifications.
• 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 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.