Foundation™(RT-SVX069A-EN) Rooftop Units: Periodical Maintenance

Once the new belts are installed, using a Browning or Gates tension gauge (or equivalent) illustrated in Figure 12; 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 O-ring is even with the top of the next belt or even with a straightedge placed across the fan and motor sheaves.

• 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 5, p. 22. 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 Table 5, p. 21.

• 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 11. Belt tension measurement and deflection ranges (in/lb)

Table 12. Belt tension measurement and deflection ranges (mm/kg)