RPS/SCU-Equal Number and Size Compressors
on Circuits (2/2/2, 3/3/3, 4/4/4, 4/2/4, 6/2/6 6/6/6,
6/3/6, 8/8/8 & 8/4/8)
With these congurations the rst step is to determine the Lead
Compressor based on Lead Circuit, WRV Control and the
Circuit Staging Method according to the table below. Once the
Lead Compressor is established and turned on, the subsequent
compressor staging is based on compressor run hours and the
Circuit Staging Method according to the table below.
If a circuit is disabled its compressors do not run and are not
considered in run hour comparisons. The Lead Compressor
is re-evaluated whenever the number of compressor stages is
zero or the maximum stages for the unit. When more than one
option is presented in the table below, the compressor with the
fewest run hours is chosen as the Lead Compressor.
Once the Lead Compressor is on, the inactive compressor with
the fewest run hours is chosen to turn on next upon a call for
increased capacity.
Upon a call for decreased capacity the operating compressor
that is not the Lead Compressor with the most run hours is
turned off next.
The Lead Compressor is turned off last upon a call for
decreased capacity.
If a circuit on a 4/2/4 or 6/2/6 conguration is disabled and then
becomes re-enabled, no change occurs until a new stage up
or down request occurs. At this time the staging is realigned to
the “normal” condition for the new stage.
NOTE: During this re-alignment, the cooling stage time
guaranteed on and off times must be observed as
well as a minimum of 10 seconds between starting
more than one compressor.
When dehumidication with hot gas reheat becomes active,
the Lead Circuit changes automatically to Lead Circuit=2 and
the Circuit Staging Method changes automatically to ALT.
When this occurs while compressors are already operating,
the staging condition must be re-aligned according to the Lead
Circuit=2 and Circuit Staging Method=ALT specication in the
table below.
NOTE: During this re-alignment, the cooling stage time
guaranteed on and off times must be observed as
well as a minimum of 10 seconds between starting
more than one compressor.
Table 19: RPS/SCU Standard Staging
Standard Staging
Staging Sequence Stage 1 Compressor Stage 2 Compressors
Std-1 1 1,2
Std-2 2 1,2
StgdClgCap 50% 100%
CoolIng: MulTIsTage
www.DaikinApplied.com 33 IM 919-3 • MICROTECH III CONTROLLER
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