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• The vibration and noise reduction is very important, and can be carried out by appropriate devices such as: resilient
joints (strongly recommended for diameters higher than 50 mm), proper insulation to separate the pipe from the wall (if the pipe
passes through the wall), flexible anchors.
• Pipe placing:
The installation of too many curves is not recommended, because each curve cause an increase rectilinear section. Moreover, the
curves must be shaped with a large curvature radius. Be extremely careful to not reduce the pipe section because it could obstruct
the normal flow of refrigerant, with consequent overwork for the compressor. The presence of too many curves in the plant could
create friction and vibration, causing at the connection points pipes and vents slackening or breakage.
• Difference in height:
The difference in height recommended by the manufacturer shall be respected between the evaporating unit and the condensing
units, otherwise cooling capacity, oil return and lubrication problems may occur.
• Flare connections
A good flare connection shall not be characterized by flash, especially in the conical contact section of the tap or of the connection
and shall be able to work without friction.
The ideal space between folder and pipe union shall be approximately 5 mm; during tightening it is recommended to apply a drop of
oil to ease locking. Be careful not to apply the oil in the contact or sealing area with the pipe union, as the oil coating will tend to dry
out.
8
LIQUID RECEIVER
The refrigerant charge of the unit depends on the heat exchanger capacity. For a reversible heat pump the heat exchangers work as
condenser or as evaporator, in accordance with the cycle. The liquid receivers are installed on the refrigerant circuit and allow to store
the charge difference between the two cycles.
The placement of the liquid receiver shall be evaluated depending on the capacity of the heat exchangers of the plant and those
installed on board of the unit.
For example:
Capacity of the heat exchanger on board: 10 liters
Capacity of the Remote heat exchanger: 6 liters
During chiller operating mode the heat exchanger on board works as a condenser, while the remote one works as evaporator. Vice
versa during heat pump mode.
The difference between the capacity of the two heat exchangers results in a refrigerant charge difference between the two cycles, it is
therefore necessary to have a liquid receiver which capacity shall be properly sized to store the excess of refrigerant when a smaller
refrigerant charge is required.
8.1 LIQUID RECEIVER SIZING
Here below an evaluation method for the liquid receiver sizing is shown. The described method is proposed to give an approximate
indication for the selection of the proper liquid receiver. The volume values obtained may change depending on the specific plant
requirements and shall therefore be evaluated in the plant design.
V
= 0.4x( V
– V
)
Receiver
1
2
V1: volume of the unit's heat exchanger (please contact TRANE to obtain this information)
V2: Volume of the remote heat exchanger.
If V receiver has positive sign, the receiver shall be placed so as to be filled in heat pump mode and discharged in chiller, otherwise it
shall be placed so as to be filled in chiller mode and emptied in the heat pump.
In addition, the liquid receiver capacity shall be sized in accordance to the total refrigerant charge of the plant, in order to store the
entire amount of refrigerant in the plant in case maintenance.
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