Start-Up Procedure; Scroll Compressor Rotation; Cooling Mode Start-Up; Heating Mode Start-Up - Carrier Aquazone 50PTH024 Installation, Start-Up And Service Instructions Manual

Table 13 — Operating Limits
AIR LIMITS
COOLING
Minimum cooling entering air
db/wb °F
Maximum cooling entering air
db/wb °F
Minimum cooling entering
fluid temp. °F
Water loop typical coil
entering fluid range
temperature °F
Maximum cooling entering
fluid temperature °F
HEATING
Minimum heating entering air
db °F
Maximum heating entering air
db °F
Normal water coil entering
fluid range °F
Minimum water coil entering
fluid °F
*Antifreeze solution is required at these fluid temperatures
LEGEND
DB — Dry Bulb
WB — Wet Bulb

Start-Up Procedure

WARNING
When the disconnect switch is closed, high voltage is present
in some areas of the electrical panel. Exercise caution when
working with the energized equipment. Failure to heed this
warning could lead to personal injury.
1. Restore power to system.
2. Turn thermostat blower position to ON or use the DDC
(direct digital control) interface to enable the unit blower. The
blower should start.
3. Balance airflow at diffusers/dampers.
4. Adjust all water valves to the full open position.
5. Use the thermostat or DDC control to enable the compressor
by placing the unit in cooling mode.
6. Verify compressor operation. If scroll compressor, verify
compressor rotation direction.

SCROLL COMPRESSOR ROTATION

It is important to be certain compressor is rotating in the proper di-
rection. To determine whether or not compressor is rotating in the
proper direction:
1. Connect service gauges to suction and discharge pressure fit-
tings.
2. Energize the compressor by using the thermostat or DDC
control to put the unit in cooling mode.
3. The suction pressure should drop and the discharge pressure
should rise, as is normal on any start-up.
EXTENDED
STANDARD
RANGE
UNIT
OPTION
68/57 68/57
95/85 95/85
70 50
70/90 70/90
110 110
50 50
80 80
50-80 25-80*
50 25*
If the suction pressure does not drop and the discharge pressure
does not rise to normal levels:
1. Turn off power to the unit. Install disconnect tag.
2. Reverse any two of the unit power leads.
3. Reapply power to the unit and verify pressures are correct.
The suction and discharge pressure levels should now move
to their normal start-up levels.
When the compressor is rotating in the wrong direction, the unit
makes more noise and does not provide cooling.
After a few minutes of reverse operation, the scroll compressor in-
ternal overload protection will open, thus activating the unit lock-
out. This requires a manual reset. To reset the lockout, turn the
thermostat on and then off or power cycle the unit power feed.
NOTE: There is a 5-minute time delay before the compressor will
re-start.

COOLING MODE START-UP

1. Using the thermostat or DDC control, operate the unit in the
cooling cycle. Refer to Table 13 for operating limits. Allow
the unit to run for a minimum of five minutes and record the
operating data.
2. Check for water leaks and vibration.
3. Check for cool air delivery at unit grille a few minutes after
the unit has begun to operate.
4. Verify that the compressor is on and that the water flow rate is
correct by measuring pressure drop through the heat
exchanger using P/T plugs. Check the elevation and cleanli-
ness of the condensate lines; any dripping could be a sign of a
blocked line. Be sure the condensate trap includes a water
seal.
5. Check the temperature of both supply and discharge water. If
temperature is within range, proceed. If temperature is out-
side the range, check the cooling refrigerant pressures in
Tables 14-23.
6. Check air temperature drop across the coil when compressor
is operating. Air temperature drop should be between 15°F
and 25°F.
7. Disable cooling mode and wait a period of 5 minutes to allow
system pressures to equalize.

HEATING MODE START-UP

1. After waiting for a period of 5 minutes after the cooling cycle,
use the thermostat or DDC control to operate the unit in the
heating cycle. Refer to Table 13 for operating limits. Allow
the unit to run for a minimum of five minutes and record the
operating data.
2. Check for water leaks and vibration.
3. Check for warm air delivery at unit grille a few minutes after
the unit has begun to operate.
4. Verify that the compressor is on and that the water flow rate is
correct by measuring pressure drop through the heat
exchanger using P/T plugs.
5. Check the temperature of both supply and discharge water.
Compare to Tables 14-23. If temperature is within range, pro-
ceed. If temperature is outside the range, check the cooling
refrigerant pressures in Tables 14-23.
6. Check air temperature rise across the coil when compressor is
operating. Air temperature rise should be between 20°F and
30°F.
7. Disable heating mode.
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