56
Air-to-Water Heat Pump
Piping and Wiring for Outdoor Unit
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 vacu-
umed 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 serv-
ice 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 leak-
age test.
If it is not available, use a stop valve for
this purpose. The "Hi" knob of the mani-
fold 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 liq-
uid soap.
To avoid nitrogen entering the refrigerant
system in a liquid state, the top of the cylin-
der 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.
2. After the system is found to be free of leaks,
relieve the nitrogen pressure by loosening the
charge hose connector at the nitrogen cylin-
der. When the system pressure is reduced to
normal, disconnect the hose from the cylinder.
Leakage test and Evacuation
Charge hose
Outdoor unit
Manifold valve
Lo
Hi
Pressure
gauge
Nitrogen gas
cylinder(in vertical
standing position)
Indoor unit
1,MFL69676201,영영 2017. 3. 8. 영영 3:07 Page 56
