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Subcooling Charging in Cooling between 55° F and 120°
OD Ambient
Trane has always recommended installing Trane
approved matched indoor and outdoor systems.
The benefits of installing approved indoor and outdoor
split systems are maximum efficiency, optimum
performance and the best overall reliability.
The following charging methods are therefore
prescribed for matched systems with indoor TXVs /
EEVs.
1. Subcooling (in the cooling mode) is the only
recommended method of charging between 55°
and 120° ambient temperatures.
2. When charging for ambient temperatures above
120°or below 55°F, charge to 10° subcooling. It is
important to return when outdoor ambient
temperature is between 55° and 120° to verify
system charge per these instructions.
3. For best results — the indoor temperature should
be kept between 70° to 80°. Add system heat if
needed.
4. Locate the designated subcooling target from the
unit nameplate.
5. At startup, or whenever charge is removed or
added, the system must be operated for a minimum
of (20) minutes to stabilize before accurate
measurements can be made.
4TWL9048A-SF-1C-EN
6. Run the system using the " " C C h h a a r r g g i i n n g g M M o o d d e e - -
C C o o o o l l i i n n g g " " mode found in the 850/950/1050 comfort
control. This is the only approved method for
setting the system charge level.
Measure Liquid Line Temperature and Refrigerant
Pressure at service valves.
7. Determine total refrigerant line length, and height
(lift) if indoor section is above the condenser.
Follow the Subcool Charging Corrections Table to
calculate additional subcooling target value.
8. Locate your liquid line temperature in the left
column of the table, and the intersecting liquid line
gage pressure under the subcool selection column.
Add refrigerant to raise the pressure to match the
table, or remove refrigerant to lower the pressure.
Always wait (20) minutes for the system conditions
to stabilize before adjusting charge again.
9. When system is correctly charged, you can refer to
System Pressure Curves to verify typical
performance.
I I m m p p o o r r t t a a n n t t : : VARIABLE SPEED OUTDOOR UNITS
REQUIRE THE INDOOR BLOWER BE
CONFIGURED FOR 400 CFM/TON
5
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