79
UNIT OPERATION
WARNING: Gloves and safety glasses must be worn when servicing refrigeration
equipment.
Before starting or operating the unit, verify all fasteners are secure and tight. In particular, check the set
screw in the wheel hub. Verify power and gas are
OFF
to the unit. Before connecting the unit to power, turn
the fan wheel by hand to verify it is not striking the inlet, or there are any obstructions. Re-center, if
necessary.
Special Tools Required for start-up: AC Voltage Meter, Standard Hand Tools, Differential Pressure Gauge,
Thermometer, Tachometer, Amperage Meter, Refrigeration Gauge Set
Start-Up Procedure
1. Check all electrical connections are secure and tight.
2. Inspect the condition of the intake damper and damper linkage, if applicable.
3. Inspect the air-stream for obstructions. Install necessary filters.
4. Verify all drains are connected and routed in the proper positions. For high-efficiency furnaces, verify
the condensate drain is connected. Refer to
“Furnace Condensation Drain” on page 15
.
5. Compare the supplied
motor
voltage
with the fan’s nameplate voltage. If this does not match, correct
the problem.
6. Check the rotation of the wheel motor. Verify the wheel is moving in the direction of the directional
arrow (
). Incorrect rotation will result in poor air performance, motor overloading, and
possible damage to the motor. If the motor rotation is incorrect, adjust using the HMI panel. Go to:
Factory Settings > Unit Options > Blower Config > Supply VFD Direction > Forward
.
7. When the fan is started, observe the operation and check for any unusual noises.
8. Connect a refrigerant gauge set to the system. Refer to
“Monitoring the A/C System” on page 103
Verify the high side and low side pressure readings are equal at the initial connection.
9. Monitor the surface temperature with a thermometer.
10. Start and run the unit for approximately 20 minutes.
11. Monitor the manifold gauge, surface temperature, subcool, and superheat readings:
- Refer to
to convert the pressure gauge readings to temperature.
- The subcool reading should be approximately
10-20°F
.
- The superheat reading should be approximately
20°F
.
Figure 35 - Direction of Rotation
