Installation Manual

9
Expansion Valve System
NOTE: Units matched with indoor coils equipped with
non-adjustable TXV should be charged by subcooling only.
1. Purge gauge lines. Connect service gauge manifold to
base-valve service ports. Run system at least 10 minutes
to allow pressure to stabilize.
2. Temporarily install a thermometer on the liquid line at the
liquid line service valve and 4-6" from the compressor on
the suction line. Ensure the thermometer makes adequate
contact and is insulated for best possible readings. Use
liquid line temperature to determine sub-cooling and va-
por temperature to determine superheat.
3. Check subcooling and superheat. Systems with TXV ap-
plication should have a subcooling of
8°F +/- 1.0°F and superheat of 8°F +/- 1.0°F.
a. If subcooling and superheat are low, adjust TXV
to 8°F +/- 1.0°F superheat, then check subcooling.
NOTE: To adjust superheat, turn the valve stem
clockwise to increase and counter clockwise to de-
crease.
b. If subcooling is low and superheat is high, add
charge to raise subcooling to 8°F +/- 1.0°F then
check superheat.
c. If subcooling and superheat are high, adjust TXV
valve to 8°F +/- 1.0°F superheat, then check
subcooling.
d. If subcooling is high and superheat is low, adjust
TXV valve to 8°F +/- 1.0°F superheat and remove
charge to lower the subcooling to 8°F +/- 1.0°F.
NOTE: Do NOT adjust the charge based on suction pres-
sure unless there is a gross undercharge.
4. Disconnect manifold set, installation is complete.
Subcooling Formula = Sat. Liquid Temp. - Liquid Line Temp.
NOTE: Check the Schrader ports for leaks and tighten valve
cores if necessary. Install caps finger-tight.