MCAC-VTSM-2015-09 R410A All DC Inverter V4+S Series 60Hz
Installation 117
5) Vacuum drying shall be conducted from liquid and gas pipe simultaneously. There are a lot of functional
parts like valves, which could shut down the gas flow midway.
11.2. 2 Special vacuum drying
Special vacuum drying method shall be adopted when:
1) Discovery of moisture during refrigerant piping flush.
2) Conducting construction on rainy day, because rain water might penetrated into pipeline.
3) Construction period is long, and rain water might penetrated into pipeline.
4) Rain water might penetrate into pipeline during construction.
Procedures of special vacuum drying are as follows:
a. First stage vacuum drying 2 hours.
b. The second vacuum damage, charging nitrogen to 7.1PSI(0.5kgf/cm
2
).
Because nitrogen is dry, vacuum damage could achieve the effect of vacuum drying, but this method cannot
sufficiently dry the system when there is too much moisture. Therefore, it is crucial to ensure that moisture
does not enter the system and condensation does not form.
c. Second stage vacuum drying 1 hour.
Vacuum drying is confirmed complete when vacuum degree is under -14.6PSI(-755mmHg); if the vacuum
degree is still above -14.6PSI(-755mmHg) within 2 hours drying, please repeat the procedures of “vacuum
damage---vacuum drying”.
d. Vacuum placement test: when the vacuum degree reaches -14.6PSI(-755mmHg), keep for 1 hour. If the
vacuum gauge indicator does not increase, the process is complete. If the vacuum gauge increases, it
indicates of moisture or a leak.
12. Additional refrigerant charge
12.1 Operation procedure for recharging refrigerant
12.1.1 Operation procedure
Calculate the required refrigerant volume by the length of liquid pipe → recharge refrigerant.
※The refrigerant volume from factory does not take into consideration actual installation piping length.
12.1.2 Steps for recharging refrigerant
1. Make sure vacuum drying is qualified before recharging refrigerant.
2. Calculate the required refrigerant volume by the diameter and the length of liquid pipe.
3. Use electronic scale or fluid infusion apparatus to weigh the recharged refrigerant volume.
4. Use soft pipe to connect refrigerant cylinder, pressure gauge, and examine valve of outdoor unit. And
recharge in liquid mode. Before recharging, clear the air in the soft pipe and pressure gauge’s pipe.
5. After recharge is finished, using gas leak detector or soap water, inspect for refrigerant leakage in expansion
part of indoor and outdoor units.
6. Write the recharged refrigerant volume in the indicating plate of outdoor unit.
Caution
1) The recharged refrigerant volume must be calculated according to the formula in the outdoor technical
reference manual. Calculation cannot be made according to running current, pressure and temperature as
current and pressure will change depending on the difference of temperature and length of pipeline.
2) In cold temperature, use warm water and hot air to warm up refrigerant storage cylinder.
12.1.3 Recharging R410A refrigerant
If R410A refrigerant is adopted, confirm the following items before recharging:
1) R410A refrigerant compatible vacuum pump with one-way valve.
2) R410A refrigerant compatible pressure gauge.
3) R410A refrigerant compatible recharging soft pipe and connector.
4) Charging method: Recharge in liquid phase.
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