12
SYSTEM VACUUM AND CHARGE
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage or improper operation.
Never use the system compressor as a vacuum pump.
CAUTION
!
Refrigerant tubes and the indoor coil should be evacuated using the
recommended 500 microns deep vacuum method. The alternate
triple evacuation method may be used if the procedure outlined
below is followed.
NOTE: Always break a vacuum with dry nitrogen.
Using Vacuum Pump
1. Completely tighten flare nuts A, B, C, D, connect the
manifold gage charge hose to a charge port of the low side
service valve (see Fig. 15).
2. Connect the charge hose to vacuum pump.
3. Fully open the low side of manifold gage (see Fig. 16).
4. Start the vacuum pump.
5. Evacuate using either the deep vacuum or triple evacuation
method.
6. After evacuation is complete, fully close the low side of
manifold gage and stop the vacuum pump operation.
7. The factory charge contained in the outdoor unit is good for
up to 25 ft. (8 m) of line length. For refrigerant lines longer
than 25 ft. (8 m), add refrigerant, up to the allowable length,
as specified in the System Requirements section.
8. Disconnect the charge hose from the charge connection of
the low side service valve.
9. Fully open service valves B and A.
10. Securely tighten the service valve caps.
Outdoor Unit
Indoor Uni
Refrigerant
Service Valve
Low Side
High Side
A
B
C
D
A07360
Fig. 15 - Service Valve
Manifold Gage
500 microns
Low side valve
High side valve
Charge hose
Charge hose
Vacuum pump
Low side valve
A07361
Fig. 16 - Manifold
Deep Vacuum Method
The deep vacuum method requires a vacuum pump capable of pulling
a vacuum of 500 microns and a vacuum gage capable of accurately
measuring this vacuum depth. The deep vacuum method is the best
way to assure a system is free of air and liquid water (see Fig. 17).
500
MINUTES
01234567
1000
1500
LEAK IN
SYSTEM
VACUUM TIGHT
TOO WET
TIGHT
DRY SYSTEM
2000
MICRONS
2500
3000
3500
4000
4500
5000
A95424
Fig. 17 - Deep Vacuum Graph
Triple Evacuation Method
The triple evacuation is the recommended method of dehydration.
Refer to Fig. 18 and proceed as follows:
1. Pump the system down to 1500 microns and allow the
pump to continue operating for an additional 15 minutes.
2. Close the service valves and shut off the vacuum pump.
3. Connect a dry nitrogen cylinder and regulator to the system
and break vacuum until the system reaches 2 psig.
4. Close the service valve and allow the system to stand for 1
hr. During this time, the dry nitrogen can diffuse throughout
the system absorbing moisture.
5. Pump the system down to 1000 microns.
6. Break the vacuum with dry nitrogen (2 psig).
7. Pump the system down to 500 microns.
8. Perform the hold test for 30 minutes.
CHECK FOR TIGHT, DRY SYSTEM
(IF IT HOLDS DEEP VACUUM)
EVACUATE TO 1500 MICRONS
EVACUATE TO 500 MICRONS MINIMUM (HOLD FOR 30 MINUTES)
RELEASE CHARGE INTO SYSTEM BY OPENING VALVES COMPLETELY
BREAK VACUUM WITH DRY NITROGEN TO 2 PSIG
EVACUATE TO 1000 MICRONS
BREAK VACUUM WITH DRY NITROGEN TO 2 PSIG
Fig. 18 - Triple Evacuation Method
Final Tubing Check
IMPORTANT: Check to be certain factory tubing on both the
indoor and outdoor unit has not shifted during shipment. Ensure
tubes are not rubbing against each other or any sheet metal. Pay
close attention to the feeder tubes, making sure wire ties on feeder
tubes are secure and tight.
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