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14.3 Weigh-In Method for Charging
Weigh-In Method can be used for the initial installation, or anytime a system charge is being replaced. Weigh-In
Method can also be used when power is not available to the equipment site or operating conditions (indoor/out-
door temperatures) are not in range to verify with the subcooling charging method.
Calculating Charge Using the Weigh-In Method
STEP 1 - Measure in feet the distance between the
outdoor unit and the indoor unit and record on Line 1.
Include the entire length of the line from the service
valve to the IDU.
STEP 2 - Enter the charge multiplier (0.6 oz/ft). Each
linear foot of interconnecting tubing requires the
addition of 0.6 oz of refrigerant.
STEP 3 - Multiply the total length of refrigerant tubing
(Line 1) times the value on Step 2. Record the result
on Line 3 of the Worksheet.
STEP 4 - This is the amount of refrigerant to weigh-in
prior to opening the service valves.
Section 15. Checkout Procedures
15.1 Operational And Checkout Procedures
Final phases of this installation are the unit Operational and Checkout Procedures. To obtain proper performance, all units
must be operated and charge adjustments made.
Important: Perform a final unit inspection to be sure that factory tubing has not shifted during shipment. Adjust tubing if nec-
essary so tubes do not rub against each other when the unit runs. Also be sure that wiring connections are tight and properly
secured.
After installation has been completed, it is recommended that the entire system be checked against the following list:
1. Leak check refrigerant lines. ........................................ [ ]
2. Properly insulate suction lines and fittings. ................... [ ]
3. Properly secure and isolate all refrigerant lines. ........... [ ]
4. Seal passages through masonry.
If mortar is used, prevent mortar from coming
into direct contact with copper tubing. .......................... [ ]
5. Verify that all electrical connections are tight. ............... [ ]
6. Observe outdoor fan during on cycle for clearance
and smooth operation. .................................................. [ ]
16
1. Line length (ft)
2. Charge multiplier
3. Step 1 x Step 2
4. Refrigerant
CHECKOUT PROCEDURE
7. Be sure that indoor coil drain line drains freely. Pour water
into drain pan. ............................................................... [ ]
8. Be sure that supply registers and return grilles are open
and unobstructed. ......................................................... [ ]
9. Be sure that a return air filter is installed. ..................... [ ]
10. Be sure that the correct airflow setting is used.
(Indoor blower motor) ................................................... [ ]
11. Operate complete system in each mode to
ensure safe operation. .................................................. [ ]
______________
x ____ 0.6 ______
= _____________
= _____________
18-AC123D1-1C-EN
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