Midea Mini VRF MDV-V105W/DN1 Technical & Service Manual page 75

R410A All DC Inverter Mini VRF
4.4 Remove Dirt or Water in the Piping
Make sure there is no any dirt or water before connecting the piping to the outdoor units.
Wash the piping with high pressure nitrogen, never use refrigerant of outdoor unit
4.5 Airtight Test
Charge pressured nitrogen after connecting indoor/outdoor unit piping to do airtight test.
Cautions:
1. Pressured nitrogen [4.3MPa (44kg/cm
2. Tighten high pressure/low pressure valves before applying pressured nitrogen.
3. Apply pressure from air vent mouth on the high pressure/low pressure valves.
4. The high pressure/low pressure valves are closed when applying pressured nitrogen.
5. The airtight test should never be used any oxygen, flammable gas or poisonous gas.
4.6 Vacuum
Using vacuum pump to do the vacuum and never using refrigerant to expel the air.
Vacuum should be done from both liquid side and gas side simultaneously.
4.7 Additional refrigerant charge
Calculate the added refrigerant according to the diameter and the length of the liquid side pipe of the outdoor
unit/indoor unit connection.
Liquid Side Piping Diameter
Note: Additional refrigerant volume of branch pipe is 0.1kg per item (Consider the liquid side of divergent pipe only)
4.8 Leak detection
Use soap water or leak detector to check every joint whether leaks or not.
Note: A is low pressure side stop valve.
B is high pressure side stop valve.
C and D are connecting pipes interface of indoor and outdoor units.
4.9 Heat insulation
Do the heat insulation to the pipes of air side and liquid side separately. The temperature of the pipes of air side
and liquid side when cooling, for avoiding condensation please do the heat insulation fully.

The air side pipe should use closed cell foamed insulation material, which the fire-retardant is B1 grade and
the heat resistance over 120° C.
When the external diameter of copper pipe≤Φ12.7mm, the thickness of the insulating layer at least more than

15mm; When the external diameter of copper pipe≥Φ15.9mm, the thickness of the insulating layer at least
more than 20mm.

Please use attached heat-insulating materials to do the heat insulation without clearance for the connecting
parts of the indoor unit pipes.
72
3
) for R410A] should be used in the airtight test.
Φ6.4
Φ9.53
Φ12.7
Φ15.9
Φ19.1
Φ22.2
B
A
Refrigerant to be Added Perimeter Piping
Check point of outdoor unit
Check point of indoor unit
MCAC-VTSM-2016-10
.
0.023kg
0.060kg
0.120kg
0.180kg
0.270kg
0.380kg
D C
Installation