Liquid Lines; Line Sizing; Routing; Insulation - Trane BCHE Installation, Operation And Maintenance Manual

Piping and Connections
Figure 48. Example of placement for split-system components
Manual
angle valves
Condensing unit
Expansion
Coil section
valves
Distributor
Frostat™ control

Liquid Lines

Line Sizing

Properly sizing the liquid line is critical to a successful split-
system application. The selected tube diameter must
provide at least 5°F [2.7°C] of subcooling at the expansion
valve throughout the operating envelope. Increasing the
size of the liquid line will not increase the available
subcooling.

Routing

Install the liquid line with a slight slope in the direction of
flow so that it can be routed with the suction line. Minimize
tube bends and reducers because these items tend to
increase pressure drop and to reduce subcooling at the
expansion valve. Liquid line receivers, other than those that
are factory-installed, are not recommended.

Insulation

The liquid line is generally warmer than the surrounding air,
so it does not require insulation. In fact, heat loss from the
liquid line improves system capacity because it provides
additional subcooling. However, if the liquid line is routed
through a high-temperature area, such as an attic or a
mechanical room, insulation would be required.
56
Discharge
line
Compressors
Check/relief valve
King valve access port
Solenoid
Moisture-
valve
indicating
sight glass
Access port
Manual
ball valve
Filter
Access
port
Liquid line
Access
Filter drier
port
with access
port
Manual
ball valve
Manual ball valve

Components

Liquid-line refrigerant components necessary for a
successful job include a filter drier, access port, solenoid
valve, moisture-indicating sight glass, expansion valve(s),
and ball shutoff valves.
proper sequence for positioning them in the liquid line.
Position the components as close to the evaporator as
possible.
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.
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
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 VAV comfort-cooling applications, and is
Access port
Manual
ball valve
Suction line
Figure 48, p. 56 illustrates the
®
valve with a core.
BCX-SVX002A-EN