System Design; Refrigerant Piping System - Mitsubishi Electric PUHY-P250YHM-A Data Book

7. System Design

7-1.Refrigerant Piping System

■ Sample connection
<Refrigerant system with one outdoor unit>
Outdoor unit
A
Allowable piping
Farthest piping length(L)
length
Allowable height Height difference between indoor
difference and outdoor units (H)
■ Pipe selection
Outdoor unit model Liquid pipe size
■ Amount of refrigerant charge
Refrigerant for extension piping is not included at factory shipment. Add an appropriate amount of refrigerant for each
system on site. Write down the size and the length of the piping in each system as well as the amount of added
refrigerant on the outdoor unit as a reference for servicing.
■ Calculating the amount of refrigerant to be added
• The amount of refrigerant that is necessary for extension piping is calculated based on the size and the length of the
liquid piping.
• Use the following formula to figure out the amount of refrigerant to be added.
• Round up the calculation result to the nearest 0.1 kg. (e.g., If the result is 16.08 kg, round up the .08 to .1 , which
yields 16.1 kg.)
<Amount of refrigerant to be added>
✻ Refrigerant charge
calculation
✻ Amount of charged
refrigerant at factory shipment
Outdoor unit Charged
model refrigerant
amount(kg)
P250
Caution
Charge Liquid Refrigerant
Filling the equipment with gas refrigerant will result in a power loss due to transformation of refrigerant in the tank.
L
Indoor unit
ø 9.52 ✻1
P250
Liquid pipe size
Total length of the
ø 12.7 pipes x 0.12
(m) x 0.12(kg/m)
✻Sample calculation
<Connection to a system with two outdoor unit>
500 model indoor unit : When ø 9.52 pipes are used and the piping length is 80 m
9.0
<Refrigerant system with two outdoor units>
Outdoor unit
A
165 m or less in actual length
50 m or less (40 m if outdoor unit is below indoor unit,
15 m if outside temperature is
Gas pipe size
✻1 Use ø 12.7 pipes when the pipe
ø 22.2
length exceeds 90 m.
Liquid pipe size
Total capacity of
connected indoor units
Total length of the
+ +
ø 9.52 pipes x 0.06
P250 model
(m) x 0.06(kg/m)
P500 model
80(m) x 0.06(kg/m)+2.0kg=6.8kg
(Amount for the extension pipe to each outdoor unit)
20
L
L
Indoor unit
10˚C or below)
Amount for the indoor unit
2.0kg
4.0kg
✻ 2 kg x 2 when connected to a
system with two outdoor units