Mitsubishi Electric ECOV-X37VA Manuel D'installation page 37

9. Refrigerant charging
9-1. Refrigerant charging procedure
Charge the system with refrigerant from the high-pressure side first.
Charging the system from the low-pressure side first may damage the compressor.
Follow the instructions below to charge refrigerant.
1. Complete vacuum drying.
2. Weigh the refrigerant cylinder. <Before charging>
3. Pressurize the system with refrigerant through the check joint on the discharge line of the compressor first.
Then, charge the system with liquid refrigerant through the check joint connected to the refrigerant service
valve (three-way valve) <liquid>.
• Charge the high-pressure side with liquid refrigerant.
Gradually add R744 in gas form to the refrigerant system until the internal pressure reaches 0.52 MPa.
If R744 is charged in liquid form when the internal pressure is below 0.52 MPa, dry ice may form inside the system.
• Open the refrigerant service valve (three-way valve) <liquid> half-way to charge refrigerant.
• Do not charge liquid refrigerant from low-pressure side first.
Charging liquid refrigerant from low-pressure side first may cause damage to the compressor.
The compressor may suffer damage if the pressure on the compressor suction side is higher than the compressor discharge
side (counter pressure).
4. Weigh the refrigerant cylinder.
5. Check that proper amount of refrigerant has been charged.
The amount of refrigerant to be charged = Cylinder weight before charging - Cylinder weight after charging
6. After the refrigerant has been charged, fully open the refrigerant service valve (three-way valve) <liquid> and
the refrigerant service valve (three-way valve) <injection>.
Then open the check joint to remove the refrigerant accumulated inside the pipe between the check joint and
the three-way valve. Close the check joint cap. Do this with both the refrigerant service valve (three-way valve)
<liquid> and the refrigerant service valve (three-way valve) <injection>. Open the refrigerant service valve
(ball valve) <suction>.
7. After test run, check the operating conditions of the system, and then add an allowable amount of refrigerant
if necessary. When adding refrigerant, charge additional refrigerant from the check joint upstream of the re-
frigerant service valve (ball valve) <suction> while operating the unit.
Compressor discharge check joint
• While the unit is stopped, the liquid pipe pressure must not exceed 8 MPa.
If the liquid pipe pressure exceeds 8 MPa, remove the refrigerant.
The liquid pipe pressure can be measured with a pressure gauge.
• After the refrigerant is charged, fully open the refrigerant service valve (three-way valve) <liquid> and the refrigerant service
valve (three-way valve) <injection>, open the check joint, remove the refrigerant accumulated inside the pipe between the
Refrigerant service valve
(ball valve) <suction>
Refrigerant service valve
(ball valve) <suction>
Upstream check joint
37
Cylinder with siphon tube
Mass
meter
Unit
cylinder
Valve
Liquid
WT09614X03_GB