System Vacuum And Charge - Carrier 38MHR series Installation Instructions Manual

SYSTEM VACUUM AND CHARGE

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. 14).
2. Connect the charge hose to vacuum pump.
3. Fully open the low side of manifold gage (see Fig. 15).
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
A
B
Service Valve
Fig. 14 - Service Valve
Manifold Gage
500 microns
Low side valve
Charge hose
Low side valve
Fig. 15 - Manifold
Refrigerant Indoor Unit
Low Side C
D
High Side
High side valve
Charge hose
Vacuum pump
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. 16).
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
Fig. 16 - Deep Vacuum Graph
Triple Evacuation Method
The triple evacuation method should only be used when the
vacuum pump is only capable of pumping down to 28 in. of
mercury vacuum and the system does not contain any liquid water.
Refer to Fig. 17 and proceed as follows:
1. Pump the system down to 28 in. of mercury 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 nitrogen cylinder and regulator to the system and
open until the system pressure is 2 psig.
4. Close the service valve and allow the system to stand for 1
hr. During this time, dry nitrogen can diffuse throughout the
system absorbing moisture.
5. Repeat this procedure as indicated in Fig. 17. The system
will then be free of any contaminants and water vapor.
BREAK VACUUM WITH DRY NITROGEN
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BREAK VACUUM WITH DRY NITROGEN
CHECK FOR TIGHT, DRY SYSTEM
RELEASE CHARGE INTO SYSTEM
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Fig. 17 - 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.
12
LEAK IN
SYSTEM
VACUUM TIGHT
TOO WET
TIGHT
DRY SYSTEM
1 2 3 4 5 6
MINUTES
EVACUATE
WAIT
EVACUATE
WAIT
EVACUATE
(IF IT HOLDS DEEP VACUUM)
7
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