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Step 7 - Evacuate Coil and Tubing System
CAUTION
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.
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. 47).
2. Connect the charge hose to vacuum pump.
3. Fully open the low side of manifold gage (see Fig. 48).
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.
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
A
B
Service Valve
Fig. 47 — Service Valve
500 microns
Low side valve
Charge hose
Low side valve
Fig. 48 — Manifold
IM-40MBAA-02
Refrigerant
Indoor Unit
Low Side
C
D
High Side
High side valve
Charge hose
Vacuum pump
Specifications subject to change without notice.
Evacuation
Evacuation of the system will remove air or nitrogen (non-condensables)
as well as moisture. A proper vacuum will assure a tight, dry system
before charging with refrigerant. The two methods used to evacuate a
system are the deep vacuum method and the triple vacuum method.
Deep Vacuum Method
The deep vacuum method requires a vacuum pump capable of pulling
a vacuum of 500 microns and a vacuum gauge capable of accurately
measuring this vacuum depth. The deep vacuum method is the most
positive way of assuring a system is free of air and moisture (see Fig.
49).
NOTE: DO NOT add a filter line drier.
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
1
2
Fig. 49 — Deep Vacuum Graph
Triple Evacuation Method
The triple evacuation method should be used when vacuum pump is
not capable of pumping down to 500 microns and system does not
contain any liquid water. Refer to Fig. 50 and proceed as follows:
1. Attach refrigeration gauges and evacuate system down to 28 in. of
mercury and allow pump to continue operating for an additional 15
minutes.
2. Close service valves and shut off vacuum pump.
3. Connect a nitrogen cylinder and regulator to system and flow
nitrogen until system pressure is 2 psig.
4. Close service valve and allow system to stand for 1 hour. During
this time, dry nitrogen can diffuse throughout the system absorbing
moisture.
5. Repeat this procedure as indicated in Fig. 50. The system should
now be free of any contaminants and water vapor.
EVACUATE
BREAK VACUUM WITH DRY NITROGEN
EVACUATE
BREAK VACUUM WITH DRY NITROGEN
EVACUATE
CHECK FOR TIGHT, DRY SYSTEM
(IF IT HOLDS DEEP VACUUM)
RELEASE CHARGE INTO SYSTEM
Fig. 50 — 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.
LEAK IN
SYSTEM
VACUUM TIGHT
TOO WET
TIGHT
DRY SYSTEM
3
4
5
6
7
WAIT
WAIT
15
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