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Piping and Wiring for Outdoor Unit
Leakage test and Evacuation
Air and moisture remaining in the refrigerant system have undesirable effects as indicated below.
1. Pressure in the system rises.
2. Operating current rises.
3. Cooling(or heating) efficiency drops.
4. Moisture in the refrigerant circuit may freeze and block capillary tubing.
5. Water may lead to corrosion of parts in the refrigeration system.
Therefore, the indoor/outdoor unit and connecting tube must be checked for leak tight, and
vacuumed to remove incondensible gas and moisture in the system.
Preparation
• Check that each tube(both liquid and gas side tubes) between the indoor and outdoor units have been
properly connected and all wiring for the test run has been completed. Remove the service valve caps
from both the gas and the liquid side on the outdoor unit. Check that both the liquid and the gas side
service valves on the outdoor unit are kept closed at this stage.
Leakage test
• Connect the manifold valve(with pressure gauges)
and dry nitrogen gas cylinder to this service port
with charge hoses.
Be sure to use a manifold valve for
leakage test.
If it is not available, use a stop valve for
this purpose. The "Hi" knob of the
manifold valve must always be kept close.
• Pressurize the system to no more than 3.0
Mpa with dry nitrogen gas and close the
cylinder valve when the gauge reading
reached 3.0 Mpa Next, test for leaks with
liquid soap.
To avoid nitrogen entering the refrigerant
system in a liquid state, the top of the
cylinder must be higher than its bottom when
you pressurize the system. Usually, the
cylinder is used in a vertical standing
position.
1. Do a leakage test of all joints of the
tubing(both indoor and outdoor) and both
gas and liquid side service valves.
Bubbles indicate a leak. Be sure to wipe off
the soap with a clean cloth.
50 Air-to-Water Heat Pump
2. After the system is found to be free of leaks,
relieve the nitrogen pressure by loosening the
charge hose connector at the nitrogen
cylinder. When the system pressure is
reduced to normal, disconnect the hose from
the cylinder.
Manifold valve
Indoor unit
Outdoor unit
Pressure "
gauge
Lo
Hi
Charge hose
Nitrogen gas"
cylinder(in vertical"
standing position)
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Troubleshooting
