2.7 AIR PURGING 2.7.1 Air purging 2.7.1 Air purging
Air and moisture remaining in the refrigerant Air and moisture remaining in the refrigerant system have undesirable effects as indicated system have undesirable effects as indicated below.
below.
●
● Pressure in the system rises.Pressure in the system rises. ●
● Operating current rises.Operating current rises.
●
● Cooling (or heating if applicable) efficiencyCooling (or heating if applicable) efficiency
drops. drops.
●
● Moisture in the refrigerant circuit may freezeMoisture in the refrigerant circuit may freeze
and block capillary tubing. and block capillary tubing.
●
● Water may lead to corrosion of parts in theWater may lead to corrosion of parts in the
refrigeration system. refrigeration system.
Therefore, the indoor unit and tubing between the Therefore, the indoor unit and tubing between the
indoor and outdoor unit must be leak tested and indoor and outdoor unit must be leak tested and evacuated to remove any non-condensable evacuated to remove any non-condensable substance and moisture from the system. substance and moisture from the system. 2.7.2 Air purging with vacuum pump 2.7.2 Air purging with vacuum pump 2.7.2.1 Preparation
2.7.2.1 Preparation
●
● Check that each tube (both liquid and gas sideCheck that each tube (both liquid and gas side
tubes) between the indoor and outdoor units have tubes) between the indoor and outdoor units have been properly connected and all wiring for the test been properly connected and all wiring for the test run has been completed. Remove the service run has been completed. Remove the service valve caps from both the gas and the liquid side valve caps from both the gas and the liquid side on the outdoor unit. Note that both the liquid and on the outdoor unit. Note that both the liquid and the gas side service valves on the outdoor unit are the gas side service valves on the outdoor unit are kept closed at this stage.
kept closed at this stage. 2.7.2.2 Leak test
2.7.2.2 Leak test
●
● Connect the manifold set (with pressureConnect the manifold set (with pressure gauges) and dry nitrogen gas cylinder to this gauges) and dry nitrogen gas cylinder to this service port with
service port with charge hoses.charge hoses.
●
● Pressurizes the system to no more than 1MPaPressurizes the system to no more than 1MPa
(Approx. 145psi) with dry nitrogen gas and close (Approx. 145psi) with dry nitrogen gas and close the cylinder valve when the gauge reading the cylinder valve when the gauge reading reaches 1MPa (Approx. 145psi). Next, test for reaches 1MPa (Approx. 145psi). Next, test for leaks with liquid soap.
leaks with liquid soap.
L
Loo HHii
Indoor unit
Indoor unit
Ou
Outdotdoor unitor unit
Manifo Manifolld sd setet Pressure Pressure gauge gauge Charge hose Charge hose Nitr
Nitroogen ggen gaass
cyli
cylinder nder ((in verticalin vertical
sta
stannding ding ppoosition)sition)
●
● Do a leak test of all joints of Do a leak test of all joints of the tubing (boththe tubing (both
indoor and outdoor) and both gas and liquid side indoor and outdoor) and both gas and liquid side service valves. Bubbles indicate a leak. Be sure service valves. Bubbles indicate a leak. Be sure toto wipe off the soap with a clean cloth.
wipe off the soap with a clean cloth.
●
● After the system is found to be free of leaks,After the system is found to be free of leaks,
relieve the nitrogen pressure by loosening the relieve the nitrogen pressure by loosening the charge hose connector at the nitrogen
charge hose connector at the nitrogen cylinder. When the system pressure is cylinder. When the system pressure is
reduced to normal, disconnect the hose from reduced to normal, disconnect the hose from the cylinder.
the cylinder. Gas leak check Gas leak check
1. Apply a soap water or a liquid neutral detergent 1. Apply a soap water or a liquid neutral detergent
CAUTION CAUTION
To avoid nitrogen entering the refrigerant To avoid nitrogen entering the refrigerant system in a liquid state, the top of the cylinder system in a liquid state, the top of the cylinder must be higher than its bottom then you
must be higher than its bottom then you
pressurise the system. Usually, the cylinder is pressurise the system. Usually, the cylinder is used in a
used in a vertical standing position.vertical standing position. CAUTION
CAUTION
Be sure to use a manifold set for air purging. If it Be sure to use a manifold set for air purging. If it
is not available, use a stop valve for this is not available, use a stop valve for this purpose. The "Hi" knob of the manifold valve purpose. The "Hi" knob of the manifold valve must always be kept closed.
on the indoor unit connection or outdoor unit on the indoor unit connection or outdoor unit connections using a soft brush to check for connections using a soft brush to check for leakage of the connecting points of the piping. leakage of the connecting points of the piping. 2. If bubbles come out, the pipes have leakage. 2. If bubbles come out, the pipes have leakage. Note: Note: A: Lo stop valve A: Lo stop valve B: Hi stop valve B: Hi stop valve
C and D: connections to the indoor unit. C and D: connections to the indoor unit.
2.7.2.3 Evacuation 2.7.2.3 Evacuation
●
● Connect the charge hose end described in theConnect the charge hose end described in the
preceding steps to the vacuum pump to evacuate preceding steps to the vacuum pump to evacuate the tubing and indoor unit. Confirm the "LO" knob the tubing and indoor unit. Confirm the "LO" knob of the manifold set is open. Then run the vacuum of the manifold set is open. Then run the vacuum pump. The operation time for evacuation varies pump. The operation time for evacuation varies with tubing length and capacity of the pump. The with tubing length and capacity of the pump. The following table is a guide for evacuation times. following table is a guide for evacuation times. Times are dependent on tubing length and pump Times are dependent on tubing length and pump capacity.
capacity.
Pipe Length (L)
Pipe Length (L) Air PurgeAir Purge Method Method Timer required Timer required (min) (min) <5m
<5m Use VacuumUse Vacuum Pump
Pump 2525
5~10m
5~10m Use VacuumUse Vacuum Pump
Pump 3030
●
● When the desired vacuum is reached, closeWhen the desired vacuum is reached, close
the "LO" knob of the manifold set and stop the the "LO" knob of the manifold set and stop the vacuum pump. vacuum pump. Indoor unit Indoor unit Outdoor unit Outdoor unit M
Manifanifold setold set
Pressure Pressure gauge gauge Vacuum pump Vacuum pump Open
Open CloseClose
2.7.2.4 Finishing the job 2.7.2.4 Finishing the job
●
● With a service valve wrench, turn the valveWith a service valve wrench, turn the valve stem of liquid side valve counter-clockwise to fully stem of liquid side valve counter-clockwise to fully open the valve.
open the valve.
●
● Turn the valve stem of gas Turn the valve stem of gas side valveside valve
counter-cl
counter-clockwise to fully ockwise to fully open the valve.open the valve.
●
● Loosen the charge hose connected to the gasLoosen the charge hose connected to the gas
side service port slightly
side service port slightly to release the pressure,to release the pressure, then remove the hose.
then remove the hose.
●
● Replace the valve cap on the Replace the valve cap on the gas side servicegas side service
port and fasten the cap securely. port and fasten the cap securely.
●
● This process is very important to preventThis process is very important to prevent
leakage from the system. leakage from the system.
●
● Replace the valve caps at both gas and liquidReplace the valve caps at both gas and liquid
side service valves and fasten them tightly. side service valves and fasten them tightly.
●
● This completes air purging with a vacuumThis completes air purging with a vacuum
pump. The air conditioner is now ready to test run. pump. The air conditioner is now ready to test run.