Start-up and Shut-down
86 CVHH-SVX001A-EN
The purge condensing-unit compressor suction
temperature varies with the amount of non-condensables
collected in the purge tank. If the amount of non-
condensables collected in the purge tank limits the
available condensing surface in the tank, the condensing-
unit compressor suction temperature begins to fall.
The purge controller initiates a pump-out cycle when the
suction temperature reaches the pump-out initiate value
that is calculated within the purge control. During the
pump-out cycle, the sm all pump-out compressor pulls any
non-condensables from the purge tank and discharges
them through the carbon tank. As the non-condensables
are removed from the purge tank, the condensing-unit
compressor suction temperature increases. The purge
controller monitors the compressor suction temperature
and cycles or stops the pump-out, depending on the
temperature that is present.
The 1/4 hp air-cooled condensing unit of the refrigeration
system operates effectively when it is in the operating
range shown in
Figure 50.
Figure 49. Adaptive chiller OFF flow chart
First chiller power-up.
Purge operates
continuously for 168
hours to collect data.
Chiller On or Off.
Chiller Off. Purge Off.
The purge control reviews the historical
pump-out data for “chiller On” and
“ chiller Off” an d det er m ines the Pum pout
Time (from the last 24 hrs, or the daily
average over the last 7 days, whichever
is greater).
Turn purge Off.
Hold purge Off for
6 hours.
Hold purge Off for
1 day.
Hold purge Off for
2 days.
Hold purge Off for
3 days.
Is Pumpout
Tim e less than
5 minutes?
Is Pumpout
Tim e less t han
3 minutes?
Is Pumpout
Tim e less t han
1 minute?
Is purge run
60 minutes
without
purging?
Run purge.
Yes
Yes
Yes
Yes
No
No
No
No
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