116
RT-SVX36G-EN
Unit Start Up
8. With the system in the SERVICE MODE and the supply fan rotating in the proper direction,
measure the amperage at the supply fan contactor 1K16 & 1K15 (additional contactor for 90 thru
75 Ton units). If the amperage exceeds the motor nameplate value, the static pressure is less
than design and the airflow is too high. If the amperage is below the motor nameplate value,
static pressure may be too high and CFM may be too low. To determine the actual CFM (± 5%);
a. Measure the actual fan RPM
b. Calculate the Theoretical BHP
c. Plot this data onto the appropriate Fan Performance Curve in
. Where the two
points intersect, read straight down to the CFM line.
Use this data to assist in calculating a new fan drive if the CFM is not at design specifications.
An alternate method with less accuracy is to measure the static pressure drop across the
evaporator coil. This can be accomplished by;
i. drilling a small hole through the unit casing on each side of the coil.
Note:
Coil damage can occur if care is not taken when drilling holes in this area.
ii. Measure the difference between the pressures at both locations.
iii. Plot this value onto the appropriate pressure drop curve in
Figure 54
. Use the data in
(Component Static Pressure Drops) to assist in calculating a new fan drive if the
CFM is not at design specifications.
iv. Plug the holes after the proper CFM has been established.
9. Press the STOP key at the Human Interface Module in the unit control panel to stop the fan
operation.
Exhaust Airflow Measurement (Optional with all Units)
1.
Close the disconnect switch or circuit protector switch that provides the supply power to the
unit's terminal block 1TB1 or the unit mounted disconnect switch 1S14.
HIGH VOLTAGE IS PRESENT AT TERMINAL BLOCK 1TB1 OR UNIT DISCONNECT
SWITCH 1S14.
2. Turn the 115 volt control circuit switch 1S1 and the 24 volt control circuit switch 1S70 to the “On”
position.
WARNING
Live Electrical Components!
During installation, testing, servicing and troubleshooting of this product, it may be necessary
to work with live electrical components. Have a qualified licensed electrician or other
individual who has been properly trained in handling live electrical components perform these
tasks. Failure to follow all electrical safety precautions when exposed to live electrical
components could result in death or serious injury.
Actual Motor Amps
X Motor HP
Motor Nameplate Amps
WARNING
Hazardous Voltage!
Disconnect all electric power, including remote disconnects before servicing. Follow proper
lockout/tagout procedures to ensure the power can not be inadvertently energized. Failure to
disconnect power before servicing could result in death or serious injury.
