Inspection and Maintenance
8-16
750-91 (revised 2009)
Model CB-LE Packaged Boiler Manual
2. Check the clearance between the impeller and backplate (see Figure 8-6). Adjust, if necessary.
FIGURE 8-5. Impeller Clearances
3. The impeller clearance is checked by inserting a long feeler gauge of the proper thickness between the impeller
and the impeller housing. Impeller clearances should be checked at the highest fin on the impeller (that fin
which is closest to the impeller housing), and must be checked at each point where the housing is attached to
the motor backplate.
4. If the impeller clearance is not correct at all points, adjust as necessary:
A. Loosen retaining nuts on both sides of the impeller housing.
B. Adjust retainers for the correct impeller clearance at two housing attachment points 180º apart.
C. Adjust retainers for correct clearance at the housing attachment points 90º from those initially adjusted.
D. Adjust for correct impeller clearance at the remaining attachment points.
5. Check and replace any gaskets that have been damaged. Gaskets that have been in use for one year or more
should be replaced. In particular, inspect the airbox gasket for damage and replace if necessary.
8.15 — Airbox Gasket Installation
If the fan/motor cassette is opened for any reason after the unit has been in operation for one year, the airbox gas-
ket should be replaced.
Attach the airbox gasket to the inlet box with high-temperature silicone adhesive/sealant, using two beads of sili-
cone about 1/4” in from each side of the gasket (gasket surface is 2” wide).
1. Secure the gasket in position with clamps, using strips of wood on top of the gasket for a bearing surface.
2. After the silicone has dried (approximately 24 hours), remove the clamps and strips of wood.
Standard 60 PPM
30 PPM
25 PPM 20 PPM
.040 +
.010 .050 + .010/-.005 .060 + .005/-.000
When replacing the airbox gasket, use only Cleaver-Brooks components. Failure to use components designed for this
application can result in improper combustion. Failure to follow these instructions could result in equipment damage.
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