SUPPLY FAN (BLOWER) SECTION
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| ! | WARNING |
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| ELECTRICAL SHOCK HAZARD | |
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| Failure to follow this warning could cause personal | |
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| injury or death. |
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| Before performing service or maintenance operations | |
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| on the fan system, shut off all unit power and | |
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| the unit disconnect switch. Do not reach into the fan | |
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| section with power still applied to unit. | |
580J |
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| Supply Fan | ||
| The supply fan system consists of a | ||
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| centrifugal blower wheel on a solid shaft with two | |
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| concentric type bearings, one on each side of the blower | |
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| housing. A | |
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| shaft and an | |
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| motor. The pulleys are connected using a “V” type belt. | |
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| (See Fig. 5.) |
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C07087
Fig. 5 - Belt Drive Motor Mounting
Belt
Check the belt condition and tension quarterly. Inspect the belt for signs of cracking, fraying or glazing along the inside surfaces. Check belt tension by using a
NOTE: Without the
Adjust belt tension by loosening the motor mounting plate front bolts and rear bolt and sliding the plate toward the fan (to reduce tension) or away from fan (to increase tension). Ensure the blower shaft and the motor shaft are parallel to each other (pulleys aligned). Tighten all bolts when finished.
To replace the belt:
1.Use a belt with same section type or similar size. Do not substitute a “FHP” type belt. When installing the
new belt, do not use a tool (screwdriver or
2.Loosen the motor mounting plate front bolts and rear bolts.
3.Push the motor and its mounting plate towards the blower housing as close as possible to reduce the cen- ter distance between fan shaft and motor shaft.
4.Remove the belt by gently lifting the old belt over one of the pulleys.
5.Install the new belt by gently sliding the belt over both pulleys and then sliding the motor and plate away from the fan housing until proper tension is achieved.
6.Check the alignment of the pulleys, adjust if neces- sary.
7.Tighten all bolts.
8.Check the tension after a few hours of runtime and
Adjustable-Pitch Pulley on Motor
The motor pulley is an
As the pitch diameter is changed by adjusting the position of the movable flange, the centerline on this pulley shifts laterally (along the motor shaft). This creates a requirement for a realignment of the pulleys after any adjustment of the movable flange. Also reset the belt tension after each realignment.
Check the condition of the motor pulley for signs of wear. Glazing of the belt contact surfaces and erosion on these surfaces are signs of improper belt tension and/or belt slippage. Pulley replacement may be necessary.
To change fan speed:
1.Shut off unit power supply.
2.Loosen belt by loosening fan motor mounting nuts. (See Fig. 5.)
3.Loosen movable pulley flange setscrew. (See Fig. 6.)
4.Screw movable flange toward fixed flange to increase speed and away from fixed flange to decrease speed. Increasing fan speed increases load on motor. Do not exceed maximum speed specified.
5.Set movable flange at nearest keyway of pulley hub and tighten setscrew to torque specifications.
To align fan and motor pulleys:
1.Loosen fan pulley setscrews.
2.Slide fan pulley along fan shaft. Make angular align- ment by loosening motor from mounting.
3.Tighten fan pulley setscrews and motor mounting bolts to torque specifications.
4.Recheck belt tension.
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