Johnson Controls York Stack Fan Operating Manual page 10

Installation (Continued)
RADIAL GAP, OVERLAP AND IMPELLER ALIGNMENT
Efficient fan performance can be maintained by having the correct gap and overlap between the impeller and inlet funnel.
These items should be checked at installation, after the fan has been in operation for 24 hours, and after the unit has been
serviced.
Gap– distance between the OD of the funnel and the ID of the impeller concentricity.
Overlap– distance the funnel and impeller overlap one another.
Gap/Overlap Dimensions
Minimum
Maximum
Model Overlap
Overlap
(Inches)
(Inches)
105 0.12 0.29
122 0.12 0.32
135 0.12 0.35
150 0.19 0.41
165 0.25 0.47
182 0.31 0.5
200 0.38 0.57
222 0.44 0.63
245 0.5 0.69
165 0.25 0.47
182 0.31 0.5
200 0.38 0.57
222 0.44 0.63
245 0.5 0.69
Minimum
Gap
(Inches)
Overlap is adjusted by loosening the impeller hub from the shaft
and moving the impeller to the desired position along the shaft.
0.06
The transition between the inlet funnel and impeller should be as
0.07
shown; there is a smooth feel to the profile when moving from one
0.07
component to the other.
0.09
This sketch shows both the gap and overlap dimensions for all sizes.
0.11
0.11
0.12
0.14
0.17
0.11
0.11
0.12
0.14
0.17
Gap is adjusted by loosening the inlet funnel
bolts and centering the funnel on the impeller.
Caution: Never loosen the motor attachment
bolts to make adjustments to the impeller-to-
funnel gap.
Overlap
Inlet Cone
YORK ® STACK FAN
Gap
Impeller
9