Centurion Water Heater- Edge [ii]: Install-Operation-Service
SECTION 9: O2 TRIM OPERATION
OMM-0153_A
• 8/25/2022 Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST Page 99 of 131
9.5
TRIM MAINTENANCE AND TROUBLESHOOTING
The O
2
Trim system depends on the O
2
sensor. It is recommended that you
inspect the
oxygen sensor
for accuracy
every 12 months
by comparing it to a sensor reading from a
properly calibrated flue analyzer. This is because contaminated air or gas supplies may cause
buildup and shift the calibration point. An offset value of ±3.0% can be entered in the
O
2
Offset
parameter in the
O
2
Trim Settings
screen (see Figure 9-4) to correct the reading during manual
calibration. If the sensor has a large amount of offset, a replacement may be required.
Occasional software updates to the device may be required.
O
2
Trim General Warnings
Warning
Cause
Possible Solutions
O
2
Percentage
Low
O
2
Levels less than 2% for more than 30
seconds (auto-reset when valve comes
back in range}
Dirty filter or poor combustion
calibration
–
recalibrate unit
O
2
Offset too low
–
Increase Offset value
Bad Sensor-Replace
O
2
Sensor
Malfunction
O
2
Levels less than -4% or more than
24% for more than 10 seconds {manual
clearing of this fault is required}
Bad Sensor-Replace
Communication Issue
–
check wires and
connections
Warning O
2
Level
High
O
2
Levels > 9% and < 24% for more
than 30 seconds {auto-reset when
value comes back in range}
Gas Pressure Regulator or Air Blower
Problem, or bad Combustion Calibration
O
2
Offset too high
Bad Sensor-Replace
O
2
Sensor Out of
Range
Sensor auto calibration offset required
is more than ±3%
Reset Unit-Recalibrate Sensor
Bad Sensor-Replace
Bad ECU-Replace (Rare)
O
2
Warning
Service Required
If the O
2
level is outside of its limits for
more than 5 minutes.
For example:
1)
Reading < Lower Limit &
Blower Voltage = BV Limit
-OR-
2)
Reading > Upper Limit &
Blower Voltage = BV Limit
Gas Supply, Air Filter, or Air Blower issue
Bad Sensor-Replace
