Johnson Controls York YKEP, Operation And Maintenance

JOHNSON CONTROLS

25

FORM 160.77-O1  

ISSUE DATE: 10/22/2020

SECTION 3 - MAINTENANCE

cator temperature will return to approximately ambient 

temperature. Close off the system again, and start the 

second evacuation.
The relatively small amount of moisture left will be 

carried out through the vacuum pump and the tem-

perature or pressure shown by the indicator should 

drop uniformly until it reaches a temperature of 35°F 

(1.6°C) or a pressure of 5 mm Hg.
When the vacuum indicator registers this tempera-

ture or pressure, it is a positive sign that the system is 

evacuated and dehydrated to the recommended limit. If 

this level cannot be reached, it is evident that there is a 

leak somewhere in the system. Any leaks must be cor-

rected before the indicator can be pulled down to 35°F 

(1.6°C) or 5 mm Hg. in the primary evacuation.
During the primary pulldown, carefully watch the wet 

bulb indicator temperature, and do not let it fall below 

35°F (1.6°C). If the temperature is allowed to fall to 

32°F (0°C), the water in the test tube will freeze, and 

the result will be a faulty temperature reading.

REFRIGERANT CHARGING

To avoid the possibility of freezing the liquid within 

the evaporator tubes when charging an evacuated sys-

tem, only refrigerant vapor from the top of the drum 

or cylinder must be admitted to the system pressure. 

Continue charging vapor only into the system until the 

system pressure is raised above the point correspond-

ing to the freezing point of the evaporator liquid. For 

water, the pressure corresponding to the freezing point 

is 29 PSIG (200 kPa) for R-134a (at sea level).
While charging, every precaution must be taken to pre-

vent moisture laden air from entering the system. Fab-

ricate a suitable charging connection from new copper 

tubing to fit between the system charging valve and the 

fitting on the charging drum. This connection should 

be as short as possible, but long enough to permit suffi-

cient flexibility for changing drums. The charging con-

nection should be purged each time a full container of 

refrigerant is connected. Changing containers should 

be done as quickly as possible to minimize the loss of 

refrigerant.
The weight of the refrigerant charged should be record-

ed after initial charging. Refrigerant may be furnished 

in cylinders containing either 30, 50, 125, 1,025 or 

1750 lbs. (13.6, 22.6, 56.6, 464 or 794 kg) of refriger-

ant.
The refrigerant charge is specified for each chiller 

model in 

Table 2 on Page 25

. Charge the correct 

amount of refrigerant and note the level in the evapora-

tor sight glass.
Proper refrigerant charge trimming is accomplished 

while running at design full load. Ensure condenser 

and economizer level settings cover the condenser 

subcooler and maintain economizer liquid seal. Then 

trim charge for design evaporator approach (leaving 

chilled liquid temperature minus refrigerant tempera-

ture) and compressor discharge superheat.

TABLE 2 - 

REFRIGERANT CHARGE

COMPRESSOR

CONDENSER

EVAPORATOR

ESTIMATE REFRIGERANT 

CHARGE LBS (KGS) 1

K7 (YDHA119) and

Q3 (HF416)

BB, BC, BD, B5, B6, B7, B8

BB

8300 (3765)

BC

7800 (3538)

BD

7320 (3320)

B6

8080 (3665)

B7

7800 (3538)

B8

7520 (3411)

1  Refrigerant charge quantity and weights will vary based on tube count. 

*   Refer to product drawings for detailed weight information.

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