Chapter 8 — Inspection and Maintenance
8-14 Part No. 750-184
1. With the IFGR damper exposed, inspect the internal linkages for secure
connections, and check for free movement of the linkage arms and the
IFGR damper assembly. To check for free movement of the linkage
separate the external linkage from the jackshaft drive arm(s) and cycle
the exterior linkage through its range of movement.
2. The clearance between the impeller and backplate should be checked,
and adjusted, if required. Impeller clearances must be as shown in Table
8-1.
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, make adjustments as
follows:
A. Loosen the retaining nuts on both sides of the impeller housing.
B. Adjust the retainers for the correct impeller clearance at two housing
attachment points 180× apart.
C. Adjust the retainers for correct clearance at the housing attachment
points 90× 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. If it needs to be replaced, refer to
Section O for installation instructions.
O. CB-LE 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 gasket should be replaced.
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 can result in equipment damage
1. Attach the airbox gasket to the inlet box with high-temperature silicone
adhesive/sealant, using two beads of silicone about 1/4” in from each
side of the gasket (gasket surface is 2" wide).
Table 1: Impeller Clearances
STANDARD
60 PPM
30 PPM
25 PPM
20 PPM
.040 ±.010 0.050 +.010/–
.005
.060 +.005/–.000
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