Start-Up - McQuay SWP Series Installation And Maintenance Manual

Start-Up

General
All units are factory tested for proper field operation.
Verify that the disconnect switch is closed, the S1 switch is
1
off, and that the crankcase heaters have been on for 24
hours.
Turn the S1 switch on to supply power to the MicroTech III
2
controller.
Set the internal MicroTech III time clock or the external
3
time clock, if used.
Set the cooling set point to a value that provides a full call
4
for cooling.
Start the auxiliary equipment for the installation such as
5
water pumps, cooling towers, etc.
Fan Start-Up
Place the unit into the FAN ONLY mode, using the
1
following keypad sequence.
System:
Control Mode =
Off
Auto
Heat/Cool
Heat only
Cool only
Fan only
Turn switch S7 to ON. The supply air fan should start and
2
run.
Observe the fan rotation. If the fan rotates backward,
3
reverse the two legs of the main unit supply power. Unit
compressors are factory "phased" to match the supply fan.
Do not reverse internal fan motor power leads since this
results in the compressor being out of phase.
If the fan does not run:
4
Check the control circuit fuse F1.
a
Verify that the fan motor protector is not tripped.
b
Check the fan motor circuit breaker is not tripped.
c
Trace the circuits.
d
Verify that the optional phase voltage monitor has not
e
tripped.
Compressor Start-Up
With the supply air fan operational, prepare for compressor
operation.
The unit ships with the refrigeration service valves
Note:
open. Check the service caps for tightness.
McQuay IM 937
System Check, Test, and Start
Connect service gauges and crack valves off the backseat
position (one turn forward). Verify that the unit has not lost its
refrigerant charge due to shipping damage or leaks. Verify that
the crankcase heaters are operating. These should operate at
least 24 hours before starting compressors.
Set Cooling Control Setpoint, to a value that provides a call
1
for full cooling.
Place the unit into the COOL ONLY mode through the
2
keypad/display.
A user may override timers for a period of up to 240
3
minutes by setting the service timer to a non-zero number.
When the service timer is not zero, the times listed below
are set to the Service Time (Default = 20 seconds) instead
of the normal values. This allows the unit to be run through
its operating states without having to wait for the normal
time delays to expire. These times revert to the standard
values when the Service Time countdown is set to zero or is
set to zero by the user. The affected times are:
• Cooling Stage Time
• Heating Stage Time
• Start Initial Time
• Recirculation
• ZeroOATime
The compressors start one at a time, beginning with
4
compressor number 1. Facing the unit, from left to right,
compressors are numbered as follows:
Independent circuit: 1, 3, 5, 6, 4, 2 or 1, 3, 4, 2
Dual circuit: 1, 3, 2, 4
If the compressor motor hums but does not run, verify that
5
the unit is getting three-phase power.
The compressors should run continuously. If a compressor
cycles on the low pressure switch:
Verify that the circuit is not low on charge.
1
Check for low airflow.
2
Check for clogged filters.
3
Check for restricted ductwork.
4
Check for very low mixed air temperatures to the unit.
5
Verify that all the distributor tubes, the expansion valve and
6
the liquid line components are feeding the evaporator coil.
Verify that all fan section access panels are in place.
7
Verify that the suction service valves and the liquid line
8
service valves are completely open.
Verify that all sensor inputs are connected.
9
Economizer Start-Up
The economizer modulates to maintain the cooling discharge
set point whenever the entering water temperature is below the
mixed air temperature to the unit by an adjustable differential
(0–10 degrees) and the unit is calling for cooling.
41