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11. SYSTEM CHARGE ADJUSTMENT
IOM
IOM
REFRIGERANT CHARGING MUST ONLY BE ATTEMPTED BY QUALIFIED CONTRACTORS. IMPROP-
ER SYSTEM CHARGE CAN REDUCE SYSTEM CAPACITY AND MAY CAUSE EQUIPMENT DAMAGE.
11.1 SYSTEM TOTAL CHARGE
DO NOT LEAVE THE SYSTEM OPEN TO THE ATMOSPHERE. DO NOT ATTEMPT TO PUMP "TOTAL
SYSTEM CHARGE" INTO OUTDOOR UNIT FOR MAINTENANCE, SERVICE, ETC. THIS MAY CAUSE
DAMAGE TO THE COMPRESSOR AND/OR OTHER COMPONENTS. THE OUTDOOR UNIT ONLY HAS
ENOUGH VOLUME FOR THE "FACTORY CHARGE", NOT FOR THE "TOTAL SYSTEM CHARGE". IT IS
UNLAWFUL TO KNOWINGLY VENT, RELEASE OR DISCHARGE REFRIGERANT INTO THE OPEN AIR
DURING REPAIR, SERVICE, MAINTENANCE, OR THE FINAL DISPOSAL OF THIS UNIT.
All air conditioning units come pre-charged with enough refrigerant (R-410A ) for an appropriately matched
indoor evaporator coil. For field installed line set, a correction of 0.6 Oz of R-410A per foot of line set is
required for 3/4" suction line diameter and 0.7 Oz of R-410A per foot of line set is required for 7/8" suction line
diameter. Liquid line shall be 3/8" diameter. Using evaporator coils that have not been approved as a match by
the manufacturer is not recommended. Refer to AHRI directory for matched evaporator coil for your system.
The system charge shall be adjusted according to section 11.2 or 11.3 depending on the application.
To obtain an efficient system matching AHRI performance, units with either thermostatic expansion
valves or piston flow raters must be installed in the vertical direction with the liquid refrigerant flowing
downwards or upwards, feeding the indoor evaporator coil. The capillary tubes and expansion valve
location can be adjusted to ensure that the flow through both of the slabs of the A-Coil have equal flow
of refrigerant. If the temperature difference does not vary more than 10°F between the two slabs of
A-coil, it indicates the equal flow of refrigerant through the each of the slabs.
11.2 ADJUSTING SYSTEM CHARGE FOR SYSTEMS USING THERMOSTATIC
EXPANSION VALVES
Procedure:
1. Connect charging hose from liquid port on the
refrigerant bottle to charging service port on
manifold gauge.
2. Open refrigerant bottle and purge hose.
3. Connect low side of manifold gauge set to the
pressure port on vapor line service valve.
4. Connect the high side of the manifold gauge set
to pressure port on liquid line service valve.
5. Temporarily install a temperature measuring device on the liquid line near the liquid service valve and
one at the vapor line near the vapor service valve. Ensure that the temperature measuring device makes
adequate contact and insulated for accurate readings.
6. Operate the system for at least 10 minutes.
7. Check subcooling and superheat. Systems using thermostatic expansion valves should have a
subcooling of 7°F to 9°F and superheat of 7°F to 9°F.
8. Record Total Charge on the nameplate and manual.
W415-2973 / B / 07.18.22
WARNING
!
WARNING
!
NOTE
!
TO PREVENT PERSONAL INJURY, CAREFULLY
CONNECT AND DISCONNECT MANIFOLD
GAUGE HOSES. ESCAPING LIQUID
REFRIGERANT CAN CAUSE BURNS. DO NOT
VENT REFRIGERANT INTO THE ATMOSPHERE.
RECOVER ALL REFRIGERANT DURING SYSTEM
REPAIR AND BEFORE FINAL UNIT DISPOSAL.
!
!
CAUTION
!
H3.96
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