516 01 3604 04
Specifications subject to change without notice.
41
Fig. 52 — EconoMi$er IV Wiring
Step 12 — Install Accessories
Available accessories include:
• Roof curb
• Thru-base connection kit (must be installed before
unit is set on curb)
• Electric heaters and single-point connection kits
• Manual outside air damper
• Two-position motorized outside air damper
• EconoMi$er
®
IV (with control)
• Power Exhaust
• Differential dry-bulb sensor (EconoMi$er IV)
• Outdoor enthalpy sensor
• Differential enthalpy sensor
• CO
2
sensor
• Smoke Detector (Return Air and/or Supply Air)
• Louvered hail guard
• Motormaster
®
head pressure controls
• Phase monitor control
Refer to separate installation instructions for information on
installing these accessories.
Step 13 — Check Belt Tension
Measure the belt span length as shown in Fig. 53. Calculate
the required deflection by multiplying the belt span length by
1
/
64
. For example, if the belt span length is 32 inches:
32 x
1
/
64
=
1
/
2
inch deflection.
BELT FORCE — DEFLECTION METHOD
Check the belt tension with a spring-force belt force deflec
-
tion gage (available from drive belt manufacturer).
1. Place a straightedge along the belt between the two
pulleys. Measure the distance between the motor
shaft and the blower shaft.
2. Set the tension gage to the desired tension (see
Table 1 in Fig. 53). Place the large O-ring at that
point.
3. Press the tension checker downward on the belt until
the large O-ring is at the bottom of the straightedge.
4. Adjust the belt tension as needed.
Adjust belt tension by loosing the motor mounting plate front
bolts and rear bolt (see Fig. 54) and slide the plate towards
the fan (to reduce tension) or away from the fan (to increase
tension). Ensure the blower shaft and motor shaft are paral
-
lel to each other (pulleys aligned). Tighten all bolts securely
when finished.
BELT TENSION METHOD
Requires belt tension gage that measures tension in belt in
units of lbs force.
