Start-Up
RT-SVX23F-EN 39
• Change indoor fan speed tap to a lower value.
Note: Minimum setting for units with Electric Heat is 320
CFM perTon.
To stop the SERVICETEST, turn the main power disconnect
switch to the "Off" position or proceed to the next
component start-up procedure.
Units with Belt Drive Indoor Fan
Much of the systems performance and reliability is closely
associated with, and dependent upon having the proper
airflow 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 SERVICETEST, set the minimum
position setpoint for the economizer to 0 percent using the
setpoint potentiometer located on the Economizer Control
(ECA), if applicable.
ReliaTel™ Control
Using the ServiceTest Guide in Table 8, p. 38, momentarily
jump across theTest 1 &Test 2 terminals on LTB1 one time
to start the Minimum VentilationTest.
Once the supply fan has started, check for proper rotation.
The direction of rotation is indicated by an arrow on the fan
housing.
With the fan operating properly, determine the total
system airflow (CFM) by;
1. Measuring the actual RPM,
2. Measure the amperage at the supply fan contactor and
compare it with the full load amp (FLA) rating stamped
on the motor nameplate.
a. Calculate the theoretical BHP using (Actual Motor
Amps/Motor Nameplate Amps) X Motor HP.
b. Using the fan performance table in the unit Service
Fact, plot the actual RPM (Step 1) and the BHP (step
2a) to obtain the operating CFM.
3. If the required CFM is too low, (external static pressure
is high causing motor HP output to be below table
value),
a. Relieve supply and/or return duct static.
b. Change indoor fan speed and repeat Step 1 and
Step 2.
• To Increase Fan RPM; Loosen the pulley adjustment set
screw and turn sheave clockwise.
• To Decrease Fan RPM; Loosen the pulley adjustment
set screw and turn sheave counterclockwise.
• If the required CFM is too high, (external static
pressure is low causing motor HP output to be above
table value), change indoor fan speed and repeat Step
1 and Step 2.
• To stop the SERVICE TEST, turn the main power
disconnect switch to the "Off" position or proceed to
the next component start-up procedure.
ReliaTel™ Units with Direct Drive Indoor
Fan (7.5 - 10 Ton Units)
Much of the systems performance and reliability is closely
associated with, and dependent upon having the proper
airflow supplied both to the space that is being
conditioned and across the evaporator coil.The indoor fan
speed is changed by adjusting the voltage from the RTOM
Indoor Fan Speed output to the direct drive plenum fan. If
installed, before starting the SERVICETEST disable the
Economizer by disconnecting the 4 pin power connector
located at the base of the Economizer Control (ECA).
Using the ServiceTest Guide in Table 8, p. 38, momentarily
jump across theTest 1 &Test 2 terminals on LTB1. Repeat
process until ServiceTest Mode is at Cool 2 (2-Steps of
Cooling Applications Only) or Cool 3 (3-Steps of Cooling
applications).The indoor motor shall be operating @
100%, to verify turn DA COOL_FAN SPD potentiometer full
clockwise, voltage should read ~7.5 Vdc across harness
test terminals.The unit schematic illustrates location for
measuring the indoor motor speed voltage.
Once the supply fan has started, determine the total
system airflow (CFM)
1. Measure the DC voltage across harness test terminals.
Using the fan rpm table shown above, determine RPM
correlated to measured voltage.
2. If the required CFM is too low, (external static pressure
is high causing motor HP output to be below table
value),
a. Relieve supply and/or return duct static.
b. Change indoor fan speed and repeat Step 1 and
Step 2.
Table 9. RPM table
Potentiometer
Voltage Motor RPM
Potentiometer
Voltage Motor RPM
1.25 217 4.50 1061
1.50 312 4.75 1126
1.75 362 5.00 1191
2.00 427 5.25 1253
2.25 479 5.50 1315
2.50 543 5.75 1374
2.75 605 6.00 1432
3.00 668 6.25 1487
3.25 732 6.50 1539
3.50 797 6.75 1588
3.75 863 7.00 1633
4.00 929 7.25 1675
4.25 995 7.50 1700
Note: Factory setting is 5V
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