Units With Constant Cfm Direct Drive Indoor; Fan; Plus Units With The Constant Cfm Direct Drive Indoor Fan - Trane TSC037E Installation, Operation And Maintenance Manual

Unit Start-Up
Electro Mechanical Control:
Guide perform the proper test mode connections.
Once the supply fan has started, determine the total
system airflow (CFM) by (ReliaTel™/Electromechanical):
1. Measure the DC voltage across pins Vt and com on the
MMC board or note the DC voltage shown on the ECM
board display. Using the fan rpm table shown above,
determine RPM correlated to measured voltage.
2. Measure the amperage at the supply fan contactor and
compare it with the full load amp (FLA) rating for the
evaporator motor stamped on the unit nameplate.
a. Calculate the theoretical BHP using (Actual Motor
Amps/Motor Nameplate Amps) X Motor HP
b. Using the fan performance tables in the unit Service
Facts, 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 steps 1 and 2.
• For MMC board:To increase or decrease fan RPM push
and turn knob counter-clockwise or clockwise
respectively. Measure the DC voltage across pins Vt
and com on the MMC. Using the fan rpm table above,
determine RPM correlated to measured voltage.
• For ECM board:To Increase/Decrease Fan RPM:
a. Push and hold the SET button for 3 sec. Board will
display Motor 1 parameter name: Hi 1.
b. Slow push SET again to display the parameter's
current value =7.50 volts.
c. Push on + or – button to adjust parameter to desired
value = XXX volts.
d. Push and hold SET button for 3 sec to "save" the
value. After save is complete, Hi 1 will show again.
e. After the voltage Hi 1 is successfully changed, the
display sequence will be:
MTR 1---> XXX -----> MTR2 -----> 0.00----->FST1---->ON/
OFF----->FST2------>ON/OFF------->EhEn--
The motor will ramp up or down to adjust to the input
signal. Using the fan rpm table above, determine RPM
correlated to displayed voltage.
• 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 steps
1 and 2.
• To stop the SERVICETEST, turn the main power
disconnect switch to the "Off" position or proceed to
the next component start-up procedure.
46
Using the ServiceTest
--->ON/OFF
Units with Constant CFM Direct 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
provides a constant CFM base on voltage output for the
potentiometer on the RTOM board. 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 9, p. 43, momentarily jump across theTest 1 &Test
2 terminals on LTB1 one time to start the Minimum
VentilationTest.
Once the supply fan has started, determine the total
system airflow (CFM) by:
1. Measure the DC voltage across pinsTP1 and ground
(screw on corner of RTOM board). Lookup desired CFM
using the voltage CFM table shown on the access panel
label or in the unit Service Facts; record corresponding
voltage. Adjust potentiometer until output voltage
acrossTP1 and ground achieves desired CFM setpoint.
2. To increase voltage/CFM, turn potentiometer
clockwise.
3. To decrease voltage/CFM, turn potentiometer counter-
clockwise.
Note: With ID fan access panel removed, fan will operate
at lower RPM due to the decrease in pressure. Once
panel is installed, RPM will increase.
17 Plus units with the constant CFM direct
drive indoor fan
Proper airflow is critical to unit operation. All 17 Plus
Precedent units (037, 047, and 067 units) use an indoor fan
that provides a constant CFM.There are two different
types of 17 Plus Precedent units: Single Zone VAV units
and Multi Speed units. Both types of units use the same
type of indoor motor and the same airflow adjustment
procedure.
To adjust airflow on a 17 Plus unit the ServiceTest mode
must be used for accurate results. Additionally, airflow
adjustments should be made in either "Cool Stage 2" or
any stage of heat because the fan is driven to its maximum
setting during these stages. Only the maximum fan setting
requires adjustment, all other fan speeds follow the
maximum adjustment and do not require any adjustment.
Using the ServiceTest Guide in
unit into either "Cool Stage 2" or any stage of heat by using
either the "StepTest Mode" or "ResistanceTest Mode" .
Once the unit is in either "Cool Stage 2" or any stage of
heat, system airflow (CFM) is determined by:
Table 9, p. 43, enter the
RT-SVX22M-EN