58
CLCH-SVX03C-EN
Coil Piping and Connections
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Filter drier. There is no substitute for cleanliness during system installation. The filter drier
prevents residual contaminants, introduced during installation, from entering the expansion
valve and solenoid valve.
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Access port. The access port allows the unit to be charged with liquid refrigerant and is used
to determine subcooling. This port is usually a Schraeder valve with a core.
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Solenoid valve. In split systems, solenoid valves isolate the refrigerant from the evaporator
during off cycles; under certain conditions, they may also trim the amount of active evaporator
as compressors unload. Generally, the “trim” solenoid valve is unnecessary for variable-air-
volume comfort-cooling applications, and is only required for constant-volume applications
when dehumidification is a concern.
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Moisture-indicating sight glass. Be sure to install one moisture-indicating sight glass in the
main liquid line. The only value of the sight glass is its moisture indication ability. Use actual
measurements of temperature and pressure—not the sight glass—to determine subcooling
and whether the system is properly charged. The moisture indicator/sight glass must be sized
to match the size of the liquid line at the thermal expansion valve.
NOTICE
Valve Damage!
Disassemble the thermal expansion valve before completing the brazing connections. If
necessary, wrap the valve in a cool, wet cloth while brazing. Failure to protect the valve from
high temperatures may result in damage to internal components.
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Thermal expansion valve. The expansion valve is the throttling device that meters the
refrigerant into the evaporator coil. Metering too much refrigerant floods the compressor;
metering too little elevates the compressor temperature. Choosing the correct size and type of
expansion valve is critical to assure it will correctly meter refrigerant into the evaporator coil
throughout the entire operating envelope of the system. Correct refrigerant distribution into the
coil requires an expansion valve for each distributor.
The thermal expansion valve must be selected for proper size and capacity. The size of the
expansion valve should cover the full range of loadings. Check that the valve will successfully
Figure 55. Type F refrigerant coil with packed elbow
Cut here
for piping
Perforated plate
(packed elbow)
Panel
Venturi type
distributor
Coil
