Yukon LWO-112, Owner'S Manual

Page: 49 / 68

FURNACE BLOWER ADJUSTMENT
Set adjustable motor pulley so blower will give
approximately 80-90º F temperature rise through furnace.
After pulley has been adjusted check bolt as follows:
The belt is drawn tight during shipment. Therefore both
belt tension and sheave alignment must be rechecked by
the installer. This is done when the furnace is placed in
service.
Improper belt tension and pulley misalignment are the
major causes of furnace fan noise. It also causes failure of
belts and bearings.
Sheave alignment is determined with a straight edge held
across outer face of fan sheave. The face of motor
sheave should be parallel to the straight edge at all points.
See Figs. 37-39
Proper belt tension is more difficult to determine
accurately. Too little tension will permit slippage causing
belt wear. It may cause noise or squealing when the motor
starts. Excessive tension increases motor load. It may
cause the oil film between shaft and bearing to fail. This,
in turn, causes the bearing to seize or burn out.
The proper belt tension is the minimum which will drive
the blower without slippage. This varies with sheave
diameter, fan size, and motor starting torque
characteristics. The practical belt tension can best be
determined by actual experience. When in doubt it is
better to have the belt too loose rather than too tight. Belt
tension can be judged by grasping the belt as shown. The
belt should be deflected approximately one inch, without
the motor moving, when moderate pressure is applied.
See Fig. 40
Questions? Visit www.yukon-eagle.com or call 1-800-358-0060
FIG. 40
FIG. 39
FIG. 38
FIG. 37
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Maintenance