Installation and Commissioning Guide - Package Commercial Unit
Doc. Part No. 0525-055 Ver. 9 220308
Installation and Commissioning Guide
Package Commercial Unit
42
SUBCOOLING AND SUPERHEAT CHARGING METHOD
Parameters:
LLT =
Liquid Line Temperature
SLT =
Suction Line Temperature
SCT =
Saturated Condensing Temperature
SST =
Saturated Suction Temperature
Cooling and Heating Operation:
Adjust the refrigerant charge to obtain the correct superheat and subcooling for optimal performance as follows:
1. Ensure that air filters are fitted and total system airflow is achieved. (Air filters are not supplied with the unit, it is the
responsibility of the installing contractor to provide and fit adequate return air and outside air filters).
2. Connect service gauges to the schrader valves.
3. Start the unit in cool mode ensuring that compressors are in 100% operation before taking service gauges reading.
Allow the system to stabilize for next 15-30 minutes before recording.
Record the discharge pressure, suction pressure, liquid line temperature and suction line temperature for all of the
refrigeration circuits:
STAGE 1
STAGE 2
(If Applicable)
Discharge Pressure:
kPa
Discharge Pressure:
kPa
Liquid Line
Temperature (
LLT
):
°C
Liquid Line
Temperature (
LLT
):
°
C
Suction Pressure:
kPa
Suction Pressure:
kPa
Suction Line
Temperature (
SLT
)
°C
Suction Line
Temperature (
SLT
)
°
C
NOTE
• Accurate pressure and temperature measuring tools should be used to achieve satisfactory results.
• The sensor of a thermocouple must be in good contact with the area being measured and must be insulated in order to
obtain correct reading.
Checking for Subcooling:
1. From the R-410A Pressure/Temperature Chart record the corresponding Saturated Condensing Temperature (
SCT
)
at the given discharge pressure.
2. Calculate the system subcooling using the formula below:
Subcooling = SCT - LLT
3. If subcooling is within the range (see charging table below), there is no need to add/remove refrigerant.
●
If subcooling is lower than minimum, the system is undercharged, it is necessary to add refrigerant.
●
If subcooling is higher than maximum, the system is over charged . It is necessary to remove refrigerant.
Allow the systems to stabilise (15-30 mins) and repeat the step 1-3 until subcooling falls within the range specified in the
table on the next page.
