Thermal Care NQ Series, Руководство по установке и эксплуатации

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32
Calculating System Refrigerant and Oil Charge
To determine the approximate charge, first refer to Table 9 and establish the require charge for the condenser and
chiller. Then refer to Table 10 to determine the charge required for the field-installed piping per circuit. The
approximate charge per circuit is therefore the sum of the values from Table 9 and Table 10.
Table 9 – Combined Chiller and Remote Condenser Summer Refrigerant Charge
Refrigeration Circuit Capacity (tons)
5 7½ 10 15 20 25 30 35 40
Refrigerant Charge (Lbs. of R-410A) 7.6 11.1 15.3 22.2 30.2 37.2 44.3 51.9 59.4
Table 10 - Field Piping R-410A Refrigerant Charge per 100 Feet of Run (Lbs.)
Line Size OD (inches) ⅜ ½ ⅝ ¾ ⅞ 1⅛ 1⅜ 1⅝ 2⅛ 2⅝
Discharge Line 0.4 0.7 1.1 1.6 2.2 3.6 5.6 7.9 13.9 21.4
Liquid Line 3.7 6.8 11.0 16.4 22.8 36.7 57.4 81.2 142.1 219.5
Oil Charge Determination
The chiller is factory charged with the amount of oil
required by the chiller only and not the total system.
The amount of oil required is dependent upon the
amount of refrigerant added to the system for the
field-installed piping. Use the following to determine
the amount of oil needed for the system.
Pints of Oil = Pounds of refrigerant in system / 100
Oil level should be checked after the chiller has run
for 15 minutes.
Setting Condenser Fan Controls
Depending on the number of condenser fans
present there will be different fan cycling pressure
control setting requirements. It is important that
these setting be correct in order to maintain proper
capacity control and operation of the system. Each
refrigerant circuit has a separate head-pressure
control circuit. Refer to Table 11 for the proper
pressure settings.
Table 11 - Condenser Fan Pressure Settings (psig)
Stage
Number
Setting
Number of Fan Stages
1 2 3 4
Stage 1
Max Speed 410 410 410 410
Min Speed 320 320 320 320
Stage 2
Fan On 400 400 370
Fan Off 340 340 305
Stage 3
Fan On 435 385
Fan Off 375 325
Stage 4
Fan On 400
Fan Off 340