6.1.4 - Unit in stand-by

The control of the unit in stand-by is completely auto￿ matic thanks to the possibility to connect the Microface control.

A unit in stand-by starts in the event of an alarm which stops the main unit; this occurs even if the main unit is switched off or disappears from the system due to a fault on the control connecting bus.

The rotation per hour of the units in stand-by occurs automatically every 24 hours, so as to allow a homoge￿ neous wear of the system components.

If the system is connected to the Hiromatic interface, it is possible to set a different rotation control.

If several units are simultaneously working with the same set point, the temperature used for the control is the average of the detected ones; further, in the operation with compressor, the proportional band is divided in as many parts as twice the number of units belonging to the system, so as to shut the total available refrigerating capacity.

The operation in Freecooling mode is homogeneous and simultaneous on all units.

Fig. b, shown as an example, describes the operation of a system consisting of 3 units.

Fig. b System with 2 units in stand-by - Microface control

Freecooling mode

P Band

3

2

1

 

 

 

 

Heating

 

Set

Cooling

￿C

 

 

Compressor cooling mode

 

 

 

 

 

P Band

 

 

3

2

1

1

2

3

 

Heating

 

Set

Cooling

￿C

1 = main unit

2 = unit in stand-by

3 = unit in stand-by

7 - Refrigerant R22 and oil charge

THESE OPERATIONS MUST BE PERFORMED BY AN EXPERIENCED REFRIGERATION TECHNI￿ CIAN.

7.1 - Features of the refrigerating fluid R22

At standard temperature and pressure it is a colourless gas with low toxicity, non-flammable, and it has an allowed exposure limit value (AEL/TLV) corresponding to 1000 ppm (average value measured on 8 hours/day). In the event of leakage, air the room before use.

7.2 - Refrigerant charge

WHEN REPAIRING THE REFRIGERATION CIR￿ CUIT RECUPERATE ALL REFRIGERANT IN A CON￿ TAINER: DO NOT ALLOW IT TO ESCAPE.

1)Start the unit as described in par. 4.1.

2)Start the compressor manually.

3)Guarantee a constant condensation temperature (preferably 42-45°C); if necessary, partially obstruct the condenser coil surface or limit its ventilating power to obtain these conditions.

4)Charge the unit with the quantity of refrigerant R22 as shown in Tab. 5 and wait until the operating condi￿ tions of the whole refrigeration circuit are normal.

5) Check that the overheating is 7-8°C.

Tab. 5 - Refrigerant charge

 

 

MODEL

 

 

 

 

 

PKS3

 

PKS4

 

 

 

 

Refrigerant charge (g)

1500

 

1700

 

 

 

 

7.3 - Oil charge

The oil to be used when topping up is SUNISO 3GS; if SUNISO 3GS is unavailable use an oil with the same characteristics (see Tab. 6).

NEVER MIX DIFFERENT OILS TOGETHER. CLEAN THE PIPING COMPLETELY BEFORE CHANGING THE TYPE OF OIL USED.

Tab. 6 - Suniso 3GS oil (standard)

approx. specific weight (at 15￿C)

:

0.91 kg/l

flash point (C.O.C.)

:

170 ￿C

pour point

:

-40 ￿C

ENGLER viscosity at 50 ￿C

:

2.7 E

viscosity index

:

0

copper corrosion (100 ￿C, 3 hours) ASTM D130

:

1

neutralization value

:

0.03 max.

conradson carbon residue

:

0%

dielectric strength

:

> 30 kV

 

 

 

page 7

English