AERCO KC Standard to Low NOx Convertion Instructions - Manual (Page 10)

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3. EQUIPMENT MODIFICATION/REWORK
The equipment items to be modified are the Air/Fuel Valve and Differential Gas Pressure Regulator.
The Air/Fuel Valve was removed from the unit in Section 2 of this Service Bulletin. The Differential
Gas Pressure Regulator can be modified in place without removal. The modification procedures for
these items are presented in paragraphs 3.1 and 3.2 which follow.
3.1 Air/Fuel Valve Modification
The modifications to be made to the Air/Fuel Valve consist of replacing the lower gas plate and the air
valve butterfly with the replacement items contained in the Conversion Kit. Place the Air/Fuel Valve
on a workbench and proceed as follows:
1. Rotate the Air/Fuel Valve butterfly so that the valve is in the fully closed position.
2. Using a 7/16 inch socket or wrench, remove the four 1/4-20 hex head machine screws
securing the lower portion of the Air/Fuel Valve body to upper valve body as shown in
Figure 8.
CAUTION
DO NOT ROTATE THE VALVE BUTTERFLY FROM THE FULLY CLOSED
POSITION AFTER SEPARATING THE UPPER AND LOWER VALVE BODY.
3. Separate the upper and lower portions of the valve body to access the gas plate as shown in
Figure 9.
4. Remove the existing gas plate with upper/lower O-rings from the Air/Fuel Valve.
5. Obtain the replacement low NOx gas plate and O-rings from the Conversion Kit. Apply O-ring
lube (Dow-Corning Compound #111, or equiv.) to the replacement O-rings and install them in
the grooves on the gas plate.(Figure 10).
6. Refer to the cut-away view in Figure 9. Ensure that the valve components are positioned as
shown in the upper valve body.
7. Position the low NOx gas plate so that the plate slot engages the locating pin in the upper
valve body (Figure 9). Also, ensure that the shutter stop pin (Figures 9 and 10) is facing the
upper portion of the valve body.
8. Apply LocTite No. 242 (Blue), or equivalent, to the threads of the four 1/4-20 hex head
machine screws removed in step 2. Reassemble and secure the lower and upper portions of
the valve body by alternately tightening the four 1/4-20 machine screws.