Earthwise Purge Sequence Of Operations; Purge Operating M Odes - Trane CVHH Installation, Operation And Maintenance Manual

tw o w eeks. This w ill prevent the accum ulation of
air and noncondensables in the m achine. To start
the purge, change the purge m ode to ON in the unit
control " Settings Purge" m enu. Rem em ber to turn
the purge m ode to "Adaptive" after the tw o-hour
run tim e.
EarthWise Purge Sequence of
Operations
A Tracer UC800 controller that is configured to control a
purge system uses the operational sequences described in
this section.

Purge Operating M odes

Purge operating m ode options are as follow s:
Stop.
The purge condensing unit does not run in this
m ode.
On.
The purge condensing unit runs continuously in this
m ode, regardless of the chillers operational status.
Auto.
The purge condensing unit runs in this m ode, if the
m ain com pressor of the chiller is operating.
Adaptive.
The purge condensing unit operation depends
on past purge activity.
Adaptive M ode
The objectives of operating the unit in the adaptive m ode
are to:
• Enable purge system operation
• Enable the refrigeration circuit to effectively
accum ulate non-condensables w hether or not the
chiller is running
• Provide inform ation to an operator regarding w hether
leakage is on the high-pressure or low-pressure side of
the chiller
• Decrease energy usage by running the purge
refrigeration circuit only w hen needed to rem ove non-
condensables, rather than running it continuously
The adaptive m ode requires historical operating data so
that the controller can m ake optim al decisions regarding
how to run the purge refrigeration circuit in the future. On
initial start-up of a chiller that is in adaptive m ode, the
purge refrigeration circuit runs continuously for 168 hours
(7 days). The chiller com pressor m ay or m ay not be
running during this period.
Follow ing the initial data collection period, the adaptive
m ode custom izes the purge refrigeration circuit operation
during tw o distinct chiller operating conditions:
• Chiller com pressor On
• Chiller com pressor Off
CVHH-SVX001A-EN
Adaptive M ode Process—Chiller Compressor
On
Figure 48, p. 84, illustrates the process described in this
subsection.
When the chiller com pressor starts, the purge refrigeration
circuit starts. The purge refrigeration circuit continues to
run until 60 consecutive m inutes of running occur w ithout
any pum p-out of non-condensables. The Pum pout Tim e is
the greater of the follow ing tw o values that the controller
has been tracking:
• The pum p-out tim e w ith the chiller On, over the last
24 hours
• The average daily pum p-out tim e w ith the chiller On,
over the last 7 days
Start-up and Shut-dow n
83