Centurion Water Heater- Edge [ii]: Install-Operation-Service
SECTION 5: INITIAL START-UP
OMM-0153_A
• 8/25/2022 Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST Page 48 of 131
NATURAL GAS Final Valve Positions
Valve Position
Standard NOx
CO
O
2
%
NOx
80%
5.6% ± 0.2%
≤20 ppm
<100 ppm
70%
5.6% ± 0.2%
≤20 ppm
<100 ppm
60%
5.6% ± 0.2%
≤20 ppm
<100 ppm
50%
5.6% ± 0.2%
≤20 ppm
<100 ppm
40%
5.8% ± 0.2%
≤20 ppm
<50 ppm
30%
5.6% ± 0.2%
≤20 ppm
<50 ppm
18%
5.6% ± 0.2%
≤20 ppm
<50 ppm
NOTE:
If NOx readings exceed the target values above, increase the O
2
level up to 1% higher
than the listed calibration range shown in the table. Record the increased O
2
value on the
Combustion Calibration sheet.
23. If the oxygen level at the lowest valve position is too high and the Blower voltage is at
minimum, you can adjust the TAC screw, recessed in the top of the Air/Fuel Valve (see
Figure 5-4, above). Rotate the screw 1/2 turn
clockwise
(CW)
to add fuel and reduce
the O
2
to the specified level. After adjusting the TAC screw, recalibration must be
performed again from 60% or 50% down to the lowest valve position.
5.3.2 Reassembly
Once the combustion calibration adjustments are properly set, the unit can be reassembled for
service operation.
1.
Set the Controller’s Enable/Disable switch to the
Disable
position.
2. Disconnect AC power to the unit.
3. Shut off the gas supply to the unit.
4. Remove the manometer and barbed fittings and reinstall the NPT plug using a suitable
pipe thread compound.
5.
Remove the combustion analyzer probe from the 1/4” vent hole in the exhaust manifold
and then replace the 1/4” NPT plug in the vent hole. Replace all previously removed
sheet metal enclosures on the unit.
5.4 OVER-TEMPERATURE LIMIT SWITCHES
The unit contains two configurable over-temperature limit controls, positioned
behind the unit’s
front panel, under the Edge Controller:
•
Automatic Reset
: If
the unit’s operating temperature exceeds the limit set on the
switch, it goes into alarm mode and shuts the unit down. When the temperature falls
10 degrees below the limit, the unit automatically resumes operation without operator
intervention. The limit range is manually adjustable from 32°F to 190°F (0°C to
87.8°C). The default value is 160°F (71.1°C).
•
Manual Reset
: If
the unit’s operating temperature exceeds the limit set on the
switch, the switch goes into alarm mode and shuts the unit down. The unit
cannot
be restarted until the switch is reset
manually
. The limit is preset to 200°F
(93.3°C) and
should not be changed
.
