Verfiying Proper Airflow - Trane YSC060 Installation Operation & Maintenance

Verifying Proper Air Flow
(Units with Belt Drive Indoor Fan)
Much of the systems performance and reliability is closely
associated with, and dependent upon having the proper air-
flow supplied both to the space that is being conditioned
and across the evaporator coil.
The indoor fan speed is changed by opening or closing the
adjustable motor sheave.
Before starting the SERVICE TEST, set the minimum posi-
tion setpoint for the economizer to 0 percent using the
setpoint potentiometer located on the Economizer Control
(ECA), if applicable.
ReliaTel Control
Using the Service Test Guide in Table 6, momentarily jump
across the Test 1 & Test 2 terminals on LTB1 one time to
start the Minimum Ventilation Test.
Once the supply fan has started, check for proper rotation.
The direction of rotation is indicated by an arrow on the fan
housing.
Use the following procedure to determine the proper adjust-
ment of the evaporator fan for a specific application.
1. With the fan operating properly, determine the total sys-
tem airflow CFM (m 3 /h) by;
a. Measuring the actual RPM,
b. Measure the amperage at the supply fan contactor
and compare it with the full load amp (FLA) rating
stamped on the motor nameplate.
c. Calculate the theoretical BHP (KW)
Actual Motor Amps X Motor HP (KW)
Motor Nameplate Amps
d. Using the fan performance tables in the unit Service
Facts, plot the actual RPM (step 1) and the theoretical
BHP (KW) (step 2c) to obtain the operating Air Flow.
2. If the required Air Flow is too low, (external static pressure
is high causing motor HP (KW) output to be below table
value), perform one or both of the following.
a. Relieve supply and/or return duct static.
b. Change indoor fan speed and repeat step 1.
RT-SVX31A-EN
Pre - Start
3. If the required CFM is too high, (external static pressure
is low causing motor HP output to be above table value),
perform one or both of the following:
a. Relieve supply and/or return duct static.
b. Change indoor fan speed and repeat step 1.
To Increase Fan RPM; Loosen the pulley adjustment set
screw and close the sheave by moving the two halves
closer together.
To Decrease Fan RPM; Loosen the pulley adjustment set
screw and open the sheave by moving the two halves far-
ther apart..
4. To stop the SERVICE TEST, turn the main power discon-
nect switch to the "Off" position or proceed to the next
component start-up procedure.
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