48
compressor will be controlled by the compressor staging rou-
tine and SUMZ Cooling Algorithm.
A1 Min Digital Capacity (
MC.A1) — This configuration de-
fines the minimum capacity the digital scroll compressor is al-
lowed to modulate to. The digital scroll compressor modula-
tion range will be limited from MC.A1 to 100%.
Dig Scroll Adjust Delta (
DS.AP) — This configuration de-
fines the maximum capacity the digital scroll will be allowed to
change per request by the SUMZ Cooling Algorithm.
Dig Scroll Adjust Delay (
DS.AD) — This configuration de-
fines the time delay in seconds between digital scroll capacity
adjustments.
Dig Scroll Reduce Delta (
DS.RP) — This configuration de-
fines the maximum capacity the digital scroll will be allowed to
decrease per request by the SUMZ Cooling Algorithm when
OAT is greater than Configuration
M.PID
DS.RO. This
ramped reduction is only imposed on a decrease in digital
scroll capacity. An increase in capacity will continue to follow
the value defined by Configuration
M.PID
DS.AP.
Dig Scroll Reduce Delay (
DS.RD) — This configuration de-
fines the time delay, in seconds, between digital scroll capacity
reduction adjustments when OAT is greater than Configura-
tion
M.PID
DS.RO. This ramped reduction is only im-
posed on a decrease in digital scroll capacity. An increase in ca-
pacity will continue to follow the value defined by Configura-
tion
M.PID
DS.AD.
Dig Scroll Reduction OAT (
DS.RO)
— Under certain operat-
ing conditions, a sharp decrease in digital scroll capacity can re-
sult in unstable unit operation. This configuration defines the
outdoor air temperature above which a reduced capacity (
Con-
figuration
M.PID
DS.RP
) and time delay (
Configura-
tion
M.PID
DS.RD
) will be imposed on a digital scroll
capacity reduction. This ramped reduction is only imposed on a
decrease in digital scroll capacity. An increase in capacity will
continue to follow the values defined by
Configura-
tion
M.PID
DS.AP
and
Configuration
M.PID
DS.AD
.
Dig Scroll Max Only OAT (DS.MO) — This configuration
defines the outdoor-air temperature above which the digital
scroll will not be allowed to modulate. The digital scroll will be
locked at 100% above this outdoor-air temperature.
Min Load Valve Enable (
MLV) — This configuration in-
structs the control as to whether a minimum load (hot gas by-
pass) valve has been installed and will be controlled by the
compressor staging routine.
High SST Alert Delay Time (
H.SST) — This option allows
the low saturated suction temperature alert timing delay to be
adjusted.
Reverse Rotation Verified? (
RR.VF) — This configuration is
used to enable or disable the compressor reverse rotation
detection algorithm. This algorithm performs a check for cor-
rect compressor rotation upon power up of the unit. The meth-
od for detecting correct rotation is based on the assumption that
there will be a drop in suction pressure upon a compressor start
if it is rotating in the correct direction.
A test is made once, on power up, for suction pressure
change on the first compressor of the first circuit to start.
Reverse rotation is determined by measuring suction pres-
sure at 3 points in time:
• 5 seconds prior to compressor start.
• At the instant the compressor starts.
• 5 seconds after the compressor starts.
The rate of suction pressure change from 5 seconds prior to
compressor start to compressor start (rate prior) is compared to
the rate of suction pressure change from compressor start to 5
seconds after compressor start (rate after).
Table 27 — Setpoints
Table 28 — Supply Air Reset Configuration
ITEM EXPANSION RANGE UNITS CCN POINT DEFAULT
OHSP Occupied Heat Setpoint 40-99 dF OHSP 68
OCSP Occupied Cool Setpoint 40-99 dF OCSP 75
UHSP Unoccupied Heat Setpoint 40-99 dF UHSP 55
UCSP Unoccupied Cool Setpoint 40-110 dF UCSP 90
GAP Heat-Cool Setpoint Gap 2-10 deltaF HCSP_GAP 5
V.C . ON VAV Occ. Cool On Delta 0-25 deltaF VAVOCON 3.5
V.C . OF VAV Occ. Cool Off Delta 1-25 deltaF VAVOCOFF 2
SASP Supply Air Setpoint 45-75 dF SASP 55
SA.HI Supply Air Setpoint Hi 45-75 dF SASP_HI 55
SA.LO Supply Air Setpoint Lo 45-75 dF SASP_LO 60
SA.HT Heating Supply Air Setpt 90-145 dF SASPHEAT 85
T.PRG Tempering Purge SASP –20-80 dF TEMPPURG 50
T.CL Tempering in Cool SASP 5-75 dF TEMPCOOL 5
T.V.OC Tempering Vent Occ SASP –20-80 dF TEMPVOCC 65
T.V.UN Tempering Vent Unocc. SASP –20-80 dF TEMPVUNC 50
ITEM EXPANSION RANGE UNITS CCN POINT DEFAULT
EDT.R EVAP.DISCHRGE TEMP RESET
RS.CF EDT Reset Configuration 0 - 3 EDRSTCFG 2
RTIO Reset Ratio 0 - 10 RTIO 3
LIMT Reset Limit 0 - 20 deltaF LIMT 10
RES.S EDT 4-20 ma Reset Input Enable/Disable EDTRSENS Disable
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