General • Maintenance

Precedent® Rooftop Units: Periodic Maintenance

This procedure is for the periodic maintenance of your equipment. It focuses on Fan Belt Adjustments.

MaintainX

10/24/2021

Precedent® Rooftop Units: Periodic Maintenance

This procedure is for the periodic maintenance of your equipment. It focuses on Fan Belt Adjustments.

Maintenance

! WARNING

Hazardous Service Procedures!

Failure to follow all precautions in this manual and on the tags, stickers, and labels could result in death or serious injury.

Technicians, in order to protect themselves from potential electrical, mechanical, and chemical hazards, MUST follow precautions in this manual and on the tags, stickers, and labels, as well as the following instructions: Unless specified otherwise, disconnect all electrical power including remote disconnect and discharge all energy storing devices such as capacitors before servicing.

Follow proper lockout/tagout procedures to ensure the power can not be inadvertently energized. When necessary to work with live electrical components, have a qualified licensed electrician or other individual who has been trained in handling live electrical components perform these tasks.

Fan Belt Adjustment - Belt Drive Units

! WARNING

Live Electrical Components!

Failure to follow all electrical safety precautions when exposed to live electrical components could result in death or serious injury. When necessary to work with live electrical components, have a qualified licensed electrician or other individual who has been properly trained in handling live electrical components perform these tasks.

! WARNING

Rotating Components!

Failure to follow all safety precautions below could result in rotating components cutting and slashing technician which could result in death or serious injury.

During installation, testing, servicing and troubleshooting of this product it may be necessary to work with live and exposed rotating components. Have a qualified or licensed service individual who has been properly trained in handling exposed rotating components, perform these tasks.

The fan belts must be inspected periodically to assure proper unit operation.

Replacement is necessary if the belts appear frayed or worn. Units with dual belts require a matched set of belts to ensure equal belt length.

When removing or installing the new belts, do not stretch them over the sheaves. Loosen the belts using the belt tension adjustment bolts on the motor mounting base.

Once the new belts are installed, using a Browning or Gates tension gauge (or equivalent) illustrated in Figure 75, p. 69, adjust the belt tension as follows:

To determine the appropriate belt deflection: a. Measure the center-to-center shaft distance (in inches) between the fan and motor sheaves. b. Divide the distance measured in Step 1a by 64; the resulting value represents the amount of belt deflection that corresponds to the proper belt tension.
Set the large O-ring on the belt tension gauge at the deflection value determined in Step 1b.
Set the small O-ring at zero on the force scale of the gauge plunger.
Place the large end of the gauge at the center of the belt span, then depress the gauge plunger until the large Oring is even with the top of the next belt or even with a straightedge placed across the fan and motor sheaves. Refer to Figure 75, p. 69.
Remove the belt tension gauge. The small O-ring now indicates a number other than zero on the plunger’s force scale. This number represents the force (in pounds) required to give the needed deflection.
Compare the “force” scale reading (Step 5) with the appropriate “force” value listed in Table 24, p. 70. If the “force” reading is outside the range, readjust the belt tension.
Note: Actual belt deflection “force” must not exceed the maximum “force” value shown in Figure 75, p. 69.
Recheck the belt tension at least twice during the first 2 to 3 days of operation. Belt tension may decrease until the new belts are “run in”.

TABLE 24. Belt tension measurement and deflection

Source: Trane (www.trane.com)

Maintenance

! WARNING

Hazardous Service Procedures!

Failure to follow all precautions in this manual and on the tags, stickers, and labels could result in death or serious injury.

Follow proper lockout/tagout procedures to ensure the power can not be inadvertently energized. When necessary to work with live electrical components, have a qualified licensed electrician or other individual who has been trained in handling live electrical components perform these tasks.

Fan Belt Adjustment - Belt Drive Units

! WARNING

Live Electrical Components!

! WARNING

Rotating Components!

Failure to follow all safety precautions below could result in rotating components cutting and slashing technician which could result in death or serious injury.

During installation, testing, servicing and troubleshooting of this product it may be necessary to work with live and exposed rotating components. Have a qualified or licensed service individual who has been properly trained in handling exposed rotating components, perform these tasks.

The fan belts must be inspected periodically to assure proper unit operation.

Replacement is necessary if the belts appear frayed or worn. Units with dual belts require a matched set of belts to ensure equal belt length.

When removing or installing the new belts, do not stretch them over the sheaves. Loosen the belts using the belt tension adjustment bolts on the motor mounting base.

Once the new belts are installed, using a Browning or Gates tension gauge (or equivalent) illustrated in Figure 75, p. 69, adjust the belt tension as follows:

To determine the appropriate belt deflection: a. Measure the center-to-center shaft distance (in inches) between the fan and motor sheaves. b. Divide the distance measured in Step 1a by 64; the resulting value represents the amount of belt deflection that corresponds to the proper belt tension.

Set the large O-ring on the belt tension gauge at the deflection value determined in Step 1b.

Set the small O-ring at zero on the force scale of the gauge plunger.

Place the large end of the gauge at the center of the belt span, then depress the gauge plunger until the large Oring is even with the top of the next belt or even with a straightedge placed across the fan and motor sheaves. Refer to Figure 75, p. 69.

Remove the belt tension gauge. The small O-ring now indicates a number other than zero on the plunger’s force scale. This number represents the force (in pounds) required to give the needed deflection.

Compare the “force” scale reading (Step 5) with the appropriate “force” value listed in Table 24, p. 70. If the “force” reading is outside the range, readjust the belt tension.

Note: Actual belt deflection “force” must not exceed the maximum “force” value shown in Figure 75, p. 69.

Recheck the belt tension at least twice during the first 2 to 3 days of operation. Belt tension may decrease until the new belts are “run in”.

TABLE 24. Belt tension measurement and deflection