Safety Control Reset; Checking System Charge; Refrigerant Charging; Troubleshooting - Carrier AQUAZONE 50KQE Series Installation, Operation And Maintenance Instructions

9.10 - Safety control reset

The 50KQE heat pumps are furnished with high pressure, low
pressure and low temperature cutouts to prevent the machine from
operating at abnormal conditions of temperature or water flow.
The contacts of the high pressure control used on 50KQE units
is designed to open at 2600 kPa and automatically re-close at
2100 kPa. The Complete C or Deluxe D control monitors this and
other functions such as refrigerant temperatures and pressures
and condensate overflow and will interrupt unit heating or
cooling operation.
The machine must be reset manually. Reset is accomplished by
pressing the STOP button and then pushing either HI HEAT,
LOW HEAT, HI COOL or LO COOL to restart the unit in the
desired mode of operation. (The 50KQE unit can also be reset
by opening and closing the supply power disconnect switch.)
NOTE: If the unit must be reset more than twice, check the
unit for a dirty filter, abnormal entering water temperature,
inadequate or excessive water flow, and internal malfunctions.
If the unit continues to cut out, contact a trained service
technician.
WARNING: When replacing the compressor contactor or
lockout relay in a unit with electromechanical controls, use
only Carrier factory authorized parts. Substitution of other
components may result in an inoperative safety circuit and
may cause a hazardous condition.

9.11 - Checking system charge

Units are shipped with full operating charge. If recharging is
necessary:
1. Insert thermometer bulb in insulating rubber sleeve on
liquid line near filter drier. Use a digital thermometer for
all temperature measurements. DO NOT use a mercury or
dial-type thermometer.
2. Connect pressure gauge to discharge line near compressor.
3. After unit conditions have stabilised, read head pressure
on discharge line gauge.
NOTE: Operate unit a minimum of 15 minutes before checking
charge.
4. From standard field-supplied pressure-temperature chart
for R-407C, find equivalent bubble point temperature.
5. Read liquid line temperature on thermometer; then
subtract from bubble point temperature. The difference
equals subcooling temperature.

9.12 - Refrigerant charging

WARNING: To prevent personal injury, wear safety glasses
and gloves when handling refrigerant. Do not overcharge
system - this can cause compressor flooding.
NOTE: Do not vent or depressurise unit refrigerant to atmos-
phere. Remove and reclaim refrigerant following accepted
practices.
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10 - TROUBLESHOOTING

When troubleshooting problems with a water-source heat pump,
consider the following and refer to Table 14:

10.1 - Thermistor

A thermistor may be required for single-phase units where
starting the unit is a problem due to low voltage.