Minimum Output Calibration; Final Check And Ignition Failure Adjustment Procedure - Watts AERCO EXT Installation, Operation & Maintenance Manual

Modulex EXT Commercial Series
CHAPTER 4: Installation Instructions

4.33.3 Minimum Output Calibration

After setting the maximum gas output for each valve (section 4.33.2), refer to Figure 4-24,
above, to locate the Minimum Gas Adjustment screw (B) on each valve. Follow the instructions
below to set the minimum gas output level for each valve.
Adjusting the Minimum (B) Gas Output Setting:
1. Operate the burner to a minimum power following the procedure described in section 4.34
"Service Mode" function (MANUAL BOILER FIRING RATE REQUEST: 10%).
2. Check that the CO
If necessary, correct the value by turning the adjustment screw "B" in a CLOCKWISE direction
3.
to increase the value or ANTICLOCKWISE to decrease it the value.
4. Repeat the adjustment for all gas valves in the boiler.
NOTE: If the CO percentage is too low, check if the air and exhaust flue are obstructed. If they are
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not obstructed, check if the burner and/or the exchanger (aluminum sections) are properly cleaned.
After confirmation, check the maximum gas settings again (in section 4.33.2).

4.33.4 Final Check and Ignition Failure Adjustment Procedure

After completing the Minimum and Maximum output adjustments, check the CO
maximum values at the flue outlet and, if necessary, make any required adjustments.
If the boiler fails to ignite, perform the following procedure:
Ignition Failure Adjustment Procedure:
Figure 4-24: Maximum Output Adjustment Screw
1. Tighten the maximum adjustment screw "A" (see Figure 4-24) in a clockwise direction until it is
fully abutted into the gas valve body, then slacken back out for nine (9) turns.
2. Verify boiler ignition.
3. If the boiler goes into lockout, slacken the screw "A" again for one turn, then retry ignition.
4. If the boiler goes into lockout again, repeat step 3 and retry ignition.
5. Once ignition succeeds, carry out the minimum and maximum gas output burner adjustments,
described in section 4.33.2 and 4.33.3, above.
OMM-0160_A • DRAFT
values are within the values indicated in Table 4-6, below.
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minimum and
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