Installation
The subcooling temperature of each system can be cal- culated by recording the temperature of the liquid line at the outlet of the condenser and subtracting it from the liquid line saturation temperature at the liquid stop valve (liquid line saturation temp. is converted from a temperature/pressure chart).
Example: |
|
Liquid line pressure = |
|
202 PSIG converted to | 102°F |
minus liquid line temp. - 87°F | |
SUBCOOLING = | 15°F |
The subcooling should be adjusted to 15°F at design conditions.
G1. Record the liquid line pressure and its correspond- ing temperature, liquid line temperature and subcooling below:
| SYS 1 SYS 2 |
Liq Line Press = | _______ _______ PSIG |
Saturated Temp = | _______ _______ °F |
Liq Line Temp = | _______ _______ °F |
Subcooling = | _______ _______ °F |
After the subcooling is verified, the suction superheat should be checked. The superheat should be checked only after steady state operation of the chiller has been established, the leaving water temperature has been pulled down to the required leaving water temperature, and the unit is running in a fully loaded condition. Cor- rect superheat setting for a system is 10°F (5.56°C) 18" (46 cm) from the cooler.
The superheat is calculated as the difference between the actual temperature of the returned refrigerant gas in the suction line entering the compressor and the tem- perature corresponding to the suction pressure as shown in a standard pressure/temperature chart.
Example: |
|
Suction Temp = | 46°F |
minus Suction Press |
|
60 PSIG converted to Temp | - 34°F |
Superheat = | 12°F |
When adjusting the expansion valve, the adjusting screw should be turned not more than one turn at a time, al- lowing sufficient time (approximately 15 minutes) be- tween adjustments for the system and the thermal ex- pansion valve to respond and stabilize.
Assure that superheat is set at 10°F (5.56°C).
G2. Record the suction temperature, suction pressure, suction saturation temperature, and superheat of each system below:
| SYS 1 SYS 2 |
Suction temp = | _______ _______ °F |
Suction Pressure = | _______ _______ PSIG |
Saturation Temp = | _______ _______ °F |
Superheat = | _______ _______ °F |
LEAK CHECKING
G1. Leak check compressors, fittings, and piping to assure no leaks.
If the unit is functioning satisfactorily during the initial operating period, no safeties trip and the compressors cycle to control water temperature to setpoint, the chiller is ready to be placed into operation.
56 | YORK INTERNATIONAL |
