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Troubleshooting (cont'd)
Operational Conditions (cont'd)
THERMOSTATDIAGNOSTICS 4. Upper Element Failure -Tests after 90 minutes of contin-
uous upper element heating without an increase in upper
The programmable thermostat will use the upper and lower water temperature. The thermostat turns off the upper ele-
temperature sensors (thermistors) to determine when either ment and tries for 30 minutes to raise the temperature of
the upper or lower heating element is not functioning. It can the upper sensor using the lower dement. If the upper tem-
also detect a faulty temperature sensor. The thermostat will use perature sensor rises using the lower element, the upper ele-
the service icon and its associated codes to indicate the specific ment will again be tried. After 30 minutes, if the upper ele-
failure condition and will also save the last failure condition, ment does not raise the upper water temperature on the
second attempt, then an upper element failure will be indi-
To display the last failure, depress and hold the up (A) arrow cated by displaying the "SERVICE" icon and the letters
"U" an " "
or the down (• ) arrow button for 4 seconds while in the nor- d E . The lower element will only be used to heat
mal run mode. Be Careful; depressing the "ERASE" button the water until the upper element has been replaced.
while the last failure is displayed will erase the stored failure.
5. Lower Element Failure- After 120 minutes of continuous
1. No Water/Dry Fire Warning - If the sensors indicate a lower element heating without an increase in lower water
rise in temperature greater than 50°F in the first minute temperature, lower element failure will be indicated by dis-
after power-up, the control will display a "NO WATER" playing the "SERVICE" icon and the letters "L" and "E'.
icon indicating that there is no water in the tank. This will Replace the lower heating element.
immediately shut offpower to both dements.
6. High Limit Device Failure - Ira lower element failure
occurs when the upper element has also failed, the thermo-
[ ] stat will determine that the high limit device has failed.
_, CAUTION High limit device failure will be indicated by displaying the
[
]
This will not discontinue power from the water
[ heater. "SERVICE" icon and the letter "C". Replace the high
limit device.
2. Upper Temperature Sensor Failure - If the upper sensor is 7. Re-Check - The system will run a failure event sequence
either open or shorted, the "SERVICE" icon and the let- three (3) times before it assumes a final service code.
ters "U" and "S" will be displayed. The thermostat will
then use only the lower heating element and lower temper-
ature sensor to control the water temperature until the
upper sensor has been replaced.
3. Lower Temperature Sensor Failure - If the lower sensor is
either open or shorted, the "SERVICE" icon and the let-
ters "L" and "S" will be displayed. The thermostat will then
use only the upper heating element and upper temperature
sensor to control the water temperature until the lower sen-
sor has been replaced.
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