Table 5 Ð Typical Deadband Requirements
UNIT | | COOLER DESIGN RANGE, F (C) |
CAPACITY | | | | | | |
STEPS | 5.0 (2.8) | 10.0 (5.6) | 15.0 (8.3) |
2 | 1.3 | (0.7) | 2.5 | (1.4) | 3.8 | (2.1) |
3 | 0.8 | (0.4) | 1.7 | (0.9) | 2.5 | (1.4) |
4 | 0.6 | (0.3) | 1.3 | (0.7) | 1.9 | (1.1) |
| | | | | | |
Table 6 Ð Deadband Setting
| MIN. REQUIRED DEADBAND | DEADBAND SETTING (F) |
| F | C |
| |
| 0.5 to 1.5 | 0.28 to 0.83 | 1.0 |
| 2.0 | 1.11 | 2.0 |
| 2.5 | 1.39 | 2.5 |
| 3.0 | 1.67 | 2.8 |
| 3.5 | 1.94 | 3.0 |
| 4.0 | 2.22 | 3.7 |
| 4.5 | 2.50 | 4.0 |
| | | |
10.Check compressor oil charge (should be visible in oil sight glass). Refer to Check Oil Charge section on page 27.
11.Be sure the compressor crankcase heater is warm (heater should be on for 24 hours before starting the compres- sor). The crankcase heater must be ®rmly locked into the compressor crankcase.
12.Be sure the compressor is ¯oating freely on the com- pressor springs (see Step 4 Ð Check Compressor Mount- ing and Connections section on page 3).
13.For 30HL and HWA units with remote condenser, check the condenser fans for correct rotation. See instructions shipped with the condenser.
14.Be sure the unit is fully charged with refrigerant (see Check Refrigerant Charge section below).
15.If unit is a brine unit, check to ensure proper brine con- centration is used to prevent freezing.
Check Refrigerant Charge
When adding or removing refrigerant charge, circulate water through condenser and cooler at all times to pre- vent freezing. Freezing damage is considered abuse and is not covered by Carrier warranty.
The 30HK, HWB, HWC, and HWS units are shipped with a full refrigerant charge (see Tables 1A-2B). However, if it is necessary to add refrigerant, operate the unit for some time at full capacity and then add charge until the sight glass is clear of bubbles. For maximum liquid subcooling, liquid level should be up to condenser end (30HK, HWC, HWS units only). This usually requires additional refrigerant charge be- yond the amount to clear sight glass.
The 30HL and HWA units (condenserless) are shipped with a refrigerant holding charge only. After chiller assembly is completed in the ®eld, system must be fully charged. While the unit is running at full capacity, add refrigerant until the sight glass is clear. R-22 is the normal refrigerant.
Do not open the liquid valve or the compressor discharge valve until there is a charge in remainder of system. A posi- tive pressure indicates a charge in system. With the unit op- erating at full load, check liquid line sight glass to be sure the unit is fully charged (bubbles in the sight glass indicate the unit is not fully charged).
If there is no refrigerant vapor pressure in the system, the entire system must be leak tested. After repairing leaks, evacu- ate the system before recharging. Follow approved evacu- ation procedures when removing refrigeration. Release re- maining pressure to an approved evacuated cylinder.
The liquid charging method is recommended for com- plete charging or when additional charge is required.
Be careful not to overcharge the system. Overcharging results in higher discharge pressure with higher cooling water consumption, possible compressor damage, and higher power consumption.
LIQUID CHARGING METHOD Ð Add charge to the unit through the liquid line service valve. Never charge liquid into the low-pressure side of the system.
1.Frontseat (close) condenser liquid line shutoff valve.
2.Connect a refrigerant cylinder loosely to the charging valve connection of the liquid line shutoff valve. Purge the charg- ing hose and tighten the connections.
3.Open the charging valve.
4.If the system has been dehydrated and is under vacuum, break the vacuum with refrigerant gas. For R-22, build up system pressure to 58 psig and 32 F (400 kPa and 0° C). Invert the refrigerant cylinder so that the liquid refrigerant will be charged.
5.a. For complete charge of 30HK, HWB, HWC, and HWS units, follow charging by weight procedure. When charge is nearly full, complete the process by observing the sight glass for clear liquid ¯ow. The use of sight glass charging is valid only when unit is operating at full capacity (no unloaders energized).
b.For complete charge of 30HL and HWA units or where refrigerant cylinder cannot be weighed, follow charg- ing by sight glass procedure. The use of sight glass charging is valid only when unit is operating at full capacity (no unloaders energized).
6.a. The 30HL and HWA condenserless units are shipped with a holding charge only. After installation with the ®eld-supplied system high side, the complete system should be charged until the sight glass is clear (with the unit running at full capacity). To achieve maxi- mum system capacity, add additional charge equal to the difference between the condenser optimal charge and the condenser minimum charge, which can be ob- tained from the charge data provided in the condenser installation instructions.
b.To ensure maximum performance of 30HWB units, raise the compressor saturated discharge temperature (SDT) to approximately 105 F (40.6 C) by throttling the condenser water intake. Add charge until there is approximately 15 to 17° F (8.3 to 9.4° C) of system subcooling (SDT minus actual temperature entering the thermostatic expansion valve).
c.To ensure maximum performance of 30HK, HWC, and HWS units, raise the compressor saturated discharge temperature (SDT) to approximately 103 F (39.4 C) by throttling the condenser water intake. Add charge until there is approximately 8 to 10° F (4.4 to 5.6° C) for 30HK units or 12 to 14° F (6.7 to 7.8° C) for 30HWC, HWS units of system subcooling (SDT minus actual temperature entering the thermostatic expansion valve).
