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 indoor coil should be evacuated using the
recommended deep vacuum method of 500 microns. The alternate
triple evacuation method may be used if the procedure outlined
below is followed. Always break a vacuum with dry nitrogen.
Using Vacuum
Pump
1. Completely tighten flare nuts A, B, C, D, (for all fan coils).
Connect gage charge hose to one circuit or all circuits (if
using a multiple connection manifold) at the low side ser-
vice valve charge port(s). (See Fig. 19.)
2. Connect charge hose to vacuum pump.
3. Fully open the low side of manifold gage. (See Fig. 20)
4. Start vacuum pump
5. Evacuate using either deep vacuum or triple evacuation
method.
6. After evacuation is complete, fully close the low side of
manifold gage and stop operation of vacuum pump.
7. If multiple connection manifold is not used, repeat the pro-
cedure (1 through 6) until all indoor units and piping are
completely vacuumed.
8. The factory charge contained in the outdoor unit is suitable
for max pipe length as shown on page 3 of this document.
If additional charge is required, it should be added to the
system as liquid at this time.
9. Disconnect charge hose from charge connection of the low
side service valve.
10. Fully open all service valves.
11. Securely tighten caps of service valves.
Outdoor Unit
Indoor Uni
Refrigerant
Service Valve
Low Side
High Side
A
B
C
D
A07360
Fig. 19 --- Service Valve
Manifold Gage
500 microns
Low side valve
High side valve
Charge hose
Charge hose
Vacuum pump
Low side valve
A07361
Fig. 20 --- 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 most positive way of assuring a system is free of air and
liquid water. (See Fig. 21)
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. 21 --- Deep Vacuum Graph
Triple Evacuation
Method
The triple evacuation method should only be used when vacuum
pump is only capable of pumping down to 28 in. of mercury
vacuum and system does not contain any liquid water.
Refer to Fig. 22 and proceed as follows:
1. Pump 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
open until system pressure is 2 psig.
4. Close service valve and allow system to stand for 1 hr. Dur-
ing this time, dry nitrogen will be able to diffuse throughout
the system absorbing moisture.
5. Repeat this procedure as indicated in Fig. 22. System will
then be free of any contaminants and water vapor.
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
A95425
Fig. 22 --- Triple Evacuation Method
Final Tubing
Check
IMPORTANT: Check to be certain factory tubing on both 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 feeder tubes, making sure wire ties on feeder tubes are
secure and tight.
38/40GVM
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