4.All pulleys are factory aligned.
5.All supply air motor pulleys are factory set at two “turns open.”
After the supply air blower motor is operating, adjust the resis- tances in both the supply and the return duct systems to bal- ance the air distribution throughout the conditioned space. The job specifications may require that this balancing be done by
FIG 4 - TYPICAL MOTOR MOUNTING ASSEMBLY
someone other than the equipment installer.
To check the supply air airflow after the the initial balancing has been completed:
1.Drill two holes 516
" (8mm) dia. in the side panel as shown in Figure 5.
2.Insert at least 8" (200mm) of 
14" (6.3mm) O.D. tubing into each of these holes for sufficient penetration into the air flow on both sides of the evaporator coil.
NOTE: The tubes must be inserted and held in a position per- pendicular to the air flow so that velocity pressure will not affect the static pressure reading.
3.Using an inclined manometer, determine the pressure drop across a dry evaporator coil. Since the moisture on an evaporator coil may vary greatly, measuring the pressure drop across a wet coil under field conditions would be inac- curate. To assure a dry coil, the refrigerant system should be
4.Knowing the pressure drop across a dry coil, the actual air- flow through the unit can be determined from the curve in Figure 6.
If the airflow is above or below the specified valve, the supply air motor pulley may have to be readjusted. After one hour of
operation, check the belt and pulleys for tightness and align- ment.
WARNING: Failure to properly adjust the total system air quan- tity can result in extensive blower damage.
After readings have been obtained, remove the tubes and seal up the drilled holes in the side panel with 516
" (8mm) dia. dot
(559)
(8)
( 4 5 7
(254)(8)
FIG 5 - HOLE LOCATIONS
TO DETERMINE PRESSURE DROP READINGS ACROSS THE DRY EVAPORATOR
plugs (P/N
NOTE; SHUT DOWN THE REFRIGERANT SYSTEM BEF- ORE TAKING ANY TEST MEASUREMENTS TO AS- SURE A DRY EVAPORATOR COIL
FIG 6 - PRESSURE DROP VS SUPPLY AIRFLOW
TABLE 4 - ELECTRICAL DATA
Blower Motor | Power Supply | FLA | LRA | Maximum | Maximum | |
HP/kW | Fuse Size* Amps | Wire Length* * Ft.(m) | ||||
|
|
| ||||
|
|
|
|
|
| |
3 / 2.2 |
| 5.2 | 37.0 | 10 | 400 (122) | |
|
|
|
|
|
|
* Dual element, time delay fuses.
** Based on three 60° C, 14 AWG, insulated copper conductors in steel conduit and a 3% voltage drop.
Unitary Products Group | 5 |