Determining Proper Expansion Valve; Operation; Determining Correct Vapor Pick-Up And Liquid Return Line Connection; Locations - Trane PRGD series Installation, Operation And Maintenance Manual

indicates a refrigerant overcharge.

Determining Proper Expansion Valve

Operation

The purpose of the expansion valve is to regulate
refrigerant flow so that a constant pressure is
maintained within the purge tank coil. A constant
pressure results in a constant temperature of the
refrigerant that is entering the purge tank.
To determine if the expansion valve is operating
properly, measure the temperature at Location 1, as
described in "Taking Surface Temperature
Measurements," p. 30. An optimum constant
temperature of -16°F (-26.6°C) is ideal. However, an
acceptable range, to allow for errors or operating
conditions, is between -20°F (-28.9°C) and -10°F (-23.3°
C).
Determining Correct Vapor Pick-up and
Liquid Return Line Connection Locations
To ensure correct purge operation, make sure that the
vapor pick-up and liquid return connections are
Table 3. Purge component status
Displayed purge status
Refrigerant Circuit On
Refrigerant Circuit Idle
Pumping Out
Regenerating
Exhaust Circuit Check
Pumpout Inhibited
Daily Pumpout Limit Disabled
Purge Diag Shutdown
Notes:
1. o = Off or de-energized
2. • = On or energized
3. X = Cycling on internal algorithm

Purge Regen Cycle

The Purge Regen Cycle is a manual control setting that
allows you to manually initiate a carbon tank
regeneration cycle.
N N o o t t e e : : This test can be initiated from either the Tracer ®
AdaptiView ™ display or the Tracer ® TU service
tool.
Run this cycle to:
• Observe the purge condensing unit stopping
• Observe the pumpout solenoid closing (if open)
• Observe the regeneration solenoid opening
• Observe the carbon tank heater energizing
• Verify that regeneration setpoints are achieved
• Verify that timing functions are correct
PRGD-SVX01F-EN
Pump-out
Condensing
compressor
unit
• o
o o
• •
X o
• •
• o
• X
o o
properly located on the chiller condenser, and are
properly sloped, as described:
• During chiller operation, non-condensables
accumulate in the coolest, calmest spot in the
condenser above the liquid level. On a Trane®
chiller this location is typically just under half-way
up the condenser shell above the condenser sump.
An internal baffle has been installed to enhance this
process during chiller operation. During chiller Off
cycles, non-condensables may rise to higher
elevations within the chiller. However, during purge
system operation, a continuous thermal siphon
develops that effectively draws the non-
condensables into the purge tank.
• Vapor pick-up and liquid return lines must be
sloped a minimum of 2 inches per foot off
horizontal or vertical to ensure that no liquid or
vapor traps exist.

Using the Service Functions

Service functions allow you to take manual control to
test the operation of specific functions. Refer to the
following table as you test the functions in this section.
Pump-out Exhaust
solenoid solenoid
o o
o o
X •
o o
• •
o o
X X
o o
For more information regarding this feature, see
"Carbon Regeneration Temperature Diagnostic
Procedure," p. 30.

Purge Exhaust Circuit Test

The Purge Exhaust Circuit Test is a manual control
setting that you can use to check that the components
activate in the right sequence and at the right time
when commanded to do so by the controls.
N N o o t t e e : : This test can be initiated from either the Tracer ®
AdaptiView ™ display or the Tracer ® TU service
tool.
This feature, when enabled, overrides the pump-out
algorithm and executes a pump-out sequence,
regardless of the actual purge refrigerant compressor
suction temperature. Once activated, the pump-out
sequence continues for 30 seconds. During this time,
T T r r o o u u b b l l e e s s h h o o o o t t i i n n g g
Regeneration Carbon tank
solenoid heater
o o
o o
o o
X X
o o
o o
o o
o o
31