McQuay M4MC Especificaciones descargar pdf (Pagina 20)

Typical service valves

Found on the outdoor unit

Most split systems have a suitable connection on the outdoor unit

Shredder valves provide easy system access for pressure reading and addition of refrigerant. On small sys-

tems, they provide a reasonable connection for evacuation also. However, Shredder valves and the hoses

connected to them can cause very severe pressure drops and can multiply evacuation time by a factor of 4

or 5.

On the positive side, Shredder valves provide a restriction that slows the speed of liquid charging into the

suction side. When a pressure drop is desirable (charging liquid into suction), connect via a Shredder valve.

When a pressure drop is detrimental (evacuation), connect via an open tting.

How Much Refrigerant?

The proper refrigerant charge should follow the volume as recommended by manufacturer and

recommendation should be followed by the installer. Refer to the table of Refrigerant Charge Level.

If the installer cannot nd the correct charge but the system must be started, refrigerant should be

carefully added to the system until reasonable sub-cooling is measured in the liquid line and reasonable

suction superheat is measured at the compressor suction. Suction and discharge pressures must be moni-

tored carefully during the charging process.

Charge Limits

Copeland Scroll compressors have the different charge limits for different compressor models as shown in

table below. If the total charge exceeds these limits, the system should have a crankcase heater and/or pump

down cycle and/or accumulator to prevent liquid damage to the compressor. Some systems may require ac-

cumulators to limit liquid oodback even though the charge is lower than the published limit.

Shredder core

Shredder valves

Shredder valve

with core in place

Shredder valve with core removed

Compressor Range Model Ibs. kg.

Quest ZR46 to ZR81 10 4.5

Summit ZR84 to ZR144 16 7.3

Specter ZR90 to ZR19M 17 7.7

1 2 ... 15 16 17 18 19 20 21 22 23 24 25 ... 66 67

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McQuay M4MC Especificaciones Pagina 20