38MAR-04SI Specifications subject to change without notice.
13
Step 5 - Evacuate Coil And Tubing System
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
2. Connect the charge hose to vacuum pump.
3. Fully open the low side of manifold gage (see Fig. 19).
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.
Fig. 18 — Service Valve
Fig. 19 — Manifold
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 Figure 20).
Fig. 20 — 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. 21 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 will be able to diffuse throughout the system
absorbing moisture.
5. Repeat this procedure as indicated in Fig. 21. System will then be
free of any contaminants and water vapor.
Fig. 21 — 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.
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
Outdoor Unit
Indoor Unit
Refrigerant
Service Valve
Low Side
High Side
A
B
C
D
500 microns
Low side valve
High side valve
Charge hose
Charge hose
Vacuum pump
Low side valve
500
MINUTES
0
1
2
3
4
5
6
7
1000
1500
LEAK IN
SYSTEM
SYSTEM TIGHT
EVACUATE MOISTURE
TIGHT DRY SYSTEM
2000
MICRONS
2500
3000
3500
4000
4500
5000
CHECK FOR TIGHT, DRY SYSTEM
(IF IT HOLDS DEEP VACUUM)
EVACUATE
BREAK VACUUM WITH DRY NITROGEN
WAIT
EVACUATE
RELEASE CHARGE INTO SYSTEM
BREAK VACUUM WITH DRY NITROGEN
EVACUATE
WAIT
