Stulz CeilAir CW - Evacuate the System

51OCH0006F08/13/2024
CEILAIR
®
CW & DX IOM
2.8.6.1 EVACUATE THE SYSTEM
2.8.6.1 Evacuate the System
CAUTION
A proper vacuum must be drawn on the refrigerant system to remove moisture prior to charging. If this is
not done, the refrigerant charge will combine with moisture in the pipes to form an acid that will eventually
lead to compressor failure. A triple evacuation procedure with dry nitrogen is recommended, especially
for systems with newly installed refrigerant piping.
NOTE Vacuum Pump Selection and Oil Quality
A vacuum pump should be used that is capable of evacuating the entire volume of the A/C system,
including newly installed or existing piping. It is essential to use a well maintained pump that is in good
operating condition. Always ensure it contains clean, fresh oil. You may need to change vacuum pump oil
more than once during the procedure.
NOTE Hose Type
Use high quality hoses, ensuring they are free of defects and do not leak. It is recommended to use
copper tubing instead of hoses if possible due to the low vacuum that must be attained when evacuating
the system. The use of short, large diameter hoses helps reduce evacuation time.
3. After ensuring there are no leaks, relieve pressure and evacuate the entire system while maintaining all
the solenoids (and hot gas reheat valve) open. Pull an initial vacuum of 1500 microns or lower using the
suction and discharge service ports and the service port of the receiver (if applicable).
NOTE Schrader Valve Removal
When pulling a vacuum, the Schrader valves will unnecessarily restrict the openings, increasing the
evacuation time. During the evacuation process it is recommended to remove the Schrader valve cores
with a Schrader valve removal tool and draw the vacuum through the port on the removal tool.
4. If you cannot evacuate the system below 1500 microns, close the vacuum pump isolation valve and
perform a rate-of-rise test by observing the standing pressure over time. If the pressure rises slowly (up
to 200 microns in 15 minutes), moisture is in the system that still needs to be boiled off. Proceed to step
#5. If the pressure rises rapidly up to atmospheric pressure (more than 50 microns per minute), there is
a leak that was not detected during step #2. In this case trouble-shoot the entire system for leaks and
repair them. Then begin the initial evacuation process again starting at step #1.
5. If no leaks are detected after the initial vacuum, release the vacuum and pressurize the system with 23
lb (0.91.4 kg) of dry nitrogen. Allow the system to stand for two hours with the dry nitrogen charge. This
gives time for the nitrogen molecules to disperse in the system absorbing moisture.
6. After two hours, release the pressure. Then turn on the vacuum pump and evacuate the system a second
time down to 1500 microns or less. Close the vacuum pump isolation valve and pressurize the system
again with dry nitrogen and allow the system to stand for two hours as in step #5.