Watts AERCO Benchmark 2.0LN, Operating & Maintenance Instructions

Page: 33 / 101

INITIAL START-UP
4-4
11. If the required oxygen level from Table 1 is
achieved, proceed to step 18. If the oxygen
level is lower than the required value and
cannot be sufficiently raised using the
differential regulator, proceed to step 12.
12. Close the 1/4” ball valve in the staged
ignition assembly downstream of the SSOV.
13. If the oxygen level rises, it is an indication
that the staged ignition solenoid is stuck, or
is adding gas and preventing the proper
oxygen level from being achieved. The
solenoid will require replacement. Proceed
to step 14.
14. Set the green ON/OFF switch to the OFF
position. Turn off AC power to the unit.
15. Replace the staged ignition solenoid. See
Figure 8.2 for location of the solenoid.
16. Re-open the 1/4” ball valve downstream of
the SSOV.
17. Repeat combustion calibration starting from
step 1 of paragraph 4.3.
18. Once the oxygen level is within the specified
range at 40%, lower the firing rate to 16%.
19. Oxygen levels at the 16% firing rate should
be as shown in Table 2. No adjustment
should be necessary. Contact the Factory if
the oxygen or carbon monoxide levels are
not within the specified range.
NOTE:
If the port being used to sample combustion
products at 16% is too far from the unit, the
readings may be shifted.
Table 2 - Combustion Oxygen Levels for a
16% Firing Rate
20. Raise the firing rate to 100%. Gas pressure
should still be 4.8” W.C. If it is not, readjust
as necessary. For Benchmark 2.0 Low NOx
boilers configured for De-Rated capacity
(see para. 2.4.1), gas pressure should still
be 3.7” W.C. If not, readjust as necessary.
21. Allow the combustion analyzer to settle.
Compare the measured oxygen level with
the levels in Table 3.
22. If the measured oxygen reading is within the
specified level in Table 3, no further
adjustment is necessary.
23. If the measured oxygen level is not within
specified range in Table 3, adjust the iris
damper as necessary until the measured
oxygen reading is within specification. (See
Figure 4.5).
Temp (ºF)
O2 CO
NOx (corrected
to 3% O
2
)
130 <20ppm <20ppm
120 <20ppm <20ppm
110 <20ppm <20ppm
100
<20ppm <20ppm
90 <20ppm <20ppm
80 <20ppm <20ppm
70 <20ppm <20ppm
60
<20ppm <20ppm
50 <20ppm <20ppm
40 <20ppm <20ppm
30 <20ppm <20ppm
20 <20ppm <20ppm
10 <20ppm <20ppm
0 <20ppm <20ppm
-10 <20ppm <20ppm
-20 <20ppm <20ppm
-30
<20ppm <20ppm
-40 <20ppm <20ppm
16% Fire Rate
4.5-8.0
5.5-8.5
6.0-9.0