8 PIPING WORK AND REFRIGERANT CHARGE
8.1 REFRIGERANT PIPE SELECTION
8.1.1 Refrigerant pipe selection
The RAS-(8-54)FSXN1E(-P) and RAS-(5-36)FSXNH(E)(-P) out-
door units can work as a heat pump system, by means of a two-
pipe system (gas pipe and liquid pipe), or they can work as a heat
recovery system by means of a three-pipe system (high and low
pressure pipes and liquid pipe), requiring in addition the CH units
supplied as accessories.
There is an optional specic pipe connection kit available accord-
ing to the power of the outdoor unit:
Operating
mode
Outdoor unit
Nº of
outdoor
units
Connection
kit
Indications
Heat
pump
system
FSXN1E
(16-P)(18-24) 2 MC-20AN1
2 pipes type
• for high/low
pressure
gas
• for liquid
(26-32) 2 MC-21AN1
(32-P)(34-48) 3 MC-30AN1
(50-54) 4 MC-40AN1
FSXNH(E)
(12-P) (14-24) 2 MC-20AN1
(24-P) (26-36) 3 MC-30AN1
Heat
recovery
system
FSXN1E
(16-P)(18-24) 2 MC-20XN1
3 pipes type
• for high/low
pressure
gas
• for low
pressure gas
• for liquid
(26-32) 2 MC-21XN1
(32-P)(34-48) 3 MC-30XN1
(50-54) 4 MC-40XN1
FSXNH(E)
(12-P) (14-24) 2 MC-20XN1
(24-P) (26-36) 3 MC-30XN1
Pipe size selection
Select the pipe size in line with the following instructions:
1 Between the outdoor unit and the branch pipe (multikit): se-
lect the same pipe connection size as for the outdoor unit.
2 Between the branch pipe (multikit) and the indoor unit: select
the same pipe connection size as for the indoor unit.
CAUTION
• Do not use refrigerant pipe sizes other than those indicated
in this manual. The diameter of the refrigerant pipes depends
directly on the power of the outdoor unit.
• If larger diameter refrigerant pipes are used, the circuit lubri-
cation oil tends to separate from the gas carrying it. The com-
pressor will be seriously damaged due to a lack of lubrication.
• If smaller diameter refrigerant pipes are used, the gas or liquid
refrigerant will have serious difculties in circulating. System
performance will be affected. The compressor will run under
more severe conditions than foreseen and will be damaged in
a short space of time.
Multikit or distributor selection
NOTE
• Pipe connection sizes on outdoor units, indoor units and the
multikit or distributor vary depending on the system. Consult
the Service Manual for the SET FREE Series FSXN1E and
FSXNH(E).
• The sizes of the indoor and outdoor units are different. Adjust
the are adapter (accessory) to the indoor pipe connection.
8.1.2 Copper pipes, sizes, connection and insulation
Copper pipes and sizes
CAUTION
• The copper pipe used in the refrigeration installations is different to the copper pipe used in installations carrying domestic or
heating water.
• The copper pipe for refrigeration installations is especially treated for outdoors and indoors. The interior surface nish makes it
easier for the refrigerant to circulate and withstands the action of the lubricant oil applied to outdoor equipment.
Prepare the copper pipes provided by the supplier.
Select the pipe with the appropriate diameter and thickness. Use the table below to select the most appropriate pipe:
Nominal diameter
Thickness mm Supply
Nominal diameter
Thickness mm Supply
mm Inches mm Inches
ø6.35 1/4 0.80 Coil ø25.4 1 1.00 Straight lenghts
ø9.52 3/8 0.80 Coil ø28.58 1-1/8 1.00 Straight lenghts
ø12.7 1/2 0.80 Coil ø31.75 1-1/4 1.10 Straight lenghts
ø15.88 5/8 1.00 Coil ø38.1 1-1/2 1.35 Straight lenghts
ø19.05 3/4 1.00 Straight lenghts ø41.3 1-5/8 1.45 Straight lenghts
ø22.2 7/8 1.00 Straight lenghts ø44.45 1-3/4 1.55 Straight lenghts
20
PMML0294A rev.2 - 07/2014
Piping work and refrigerant charge
PMML0294A_rev.2_02-2014.indb 20 14/07/2014 12:28:10
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