Check Retention Head Alignment And Cad Cell Sighting; Check/Adjust "Zero" Calibration; Blower Wheel Replacement; Shutting The Burner Off - Weil-McLain UO-3 CV Instruction Manual

Section: Trained Service Technician's Regular Maintenance
Check Retention Head Alignment and Cad
Cell Sighting
(Refer to Figure 13.)
The cad cell sighting holes in the throttle cup and the
retention head must be aligned to allow the cad cell
to detect the fl ame. Make sure the stamped key in the
retention head collar lines up with the keyway in the
nozzle adapter when mounting the retention head. Note
that in specifi c applications, the retention head may not
have a sighting hole.

Check/Adjust "Zero" Calibration

On burners with factory-installed air tubes, the zero
calibration has been factory set. Make sure the retention
head (Figure 10) is securely against the stops in the
retention ring when the adjustment plate pointer is at "0"
(Figure 9).
If the zero calibration has not been set, perform the
following procedure:
1. Install the nozzle line, with the adjustment plate
assembly attached, into the burner.
2. Install and tighten the rear door to hold the air
adjustment plate assembly in position.
3. Slightly loosen the upper acorn nut, the splined nut,
and the lower acorn nut.
20
4. Turn the air adjustment screw clockwise to adjust
the plate with the pointer to the zero position.
5. Referring to Figure 10, slide the nozzle line
assembly forward until the retention head engages
the fi xed stops in the retention ring at the end of the
air tube.
6. Tighten the upper acorn nut securely.
7. The rear door must be kept tightly closed. The
adjustment screw may now be turned to adjust the
head/air setting.
8. Turn the adjusting screw to a setting ½ number
lower than the proper set point as indicated in Table
1. Then turn the adjusting screw counterclockwise
to the proper setting.
9. Tighten the splined nut and lower acorn nut after
the head/air setting has been adjusted.

Blower Wheel Replacement

For installation or replacement of a blower wheel, insure
that there is a space between the blower wheel and the
motor face of 0.115". Refer to Figure 14.

Shutting the Burner Off

Turn off all electric power to the burner.
Note: There could be more than one disconnect switch.
If the burner is shut down
for an extended period of
time, always keep the valve shut off.