Carrier WeatherExpert 48N2 Controls, Start-Up, Operation, Service, And Troubleshooting page 49

ITEM
EX.SL EXV Init Pos Slope
EX.IN EXV Init Pos Intercept
EX.SM
EXV Smoothing Algorithm
EX.EP SH Error Exponent
DP.OC
DP OVERRIDE CONFIGS
DP.RS DP Rate of Change Set
DP.RC
DP Rate of Change Clr
DP.L1 DP Override Limit 1
DP.L2
DP Override Limit 2
DP.TO DP Override Timeout
DP.OR
DP Override Percent
ITEM
OHSP Occupied Heat Setpoint
OCSP Occupied Cool Setpoint
UHSP Unoccupied Heat Setpoint
UCSP Unoccupied Cool Setpoint
GAP Heat-Cool Setpoint Gap
V.C.ON VAV Occ. Cool On Delta
V.C.OF VAV Occ. Cool Off Delta
SASP Supply Air Setpoint
SA.HI Supply Air Setpoint Hi
SA.LO Supply Air Setpoint Lo
SA.HT Heating Supply Air Setpt
T.PRG Tempering Purge SASP
T.CL Tempering in Cool SASP
T.V.OC Tempering Vent Occ SASP
T.V.UN
Tempering Vent Unocc. SASP
Cool Mode Determination
If the machine control type (Configuration  UNIT  C.TYP) =
1 (VAV-RAT) or 2 (VAV-SPT) and the control is occupied (Oper-
ating Modes  MODE  OCC=ON), then the unit will not follow
the occupied cooling set point (OCSP). Instead, the control will
follow 2 offsets in the determination of an occupied VAV cooling
mode (Setpoints  V.C.ON and Setpoints  V.C.OF), applying
them to the low-heat off trip point and comparing the resulting
temperature to the controlling return temperature (R.TMP).
The Setpoints  V.C.ON (VAV cool mode on offset) and Set-
points  V.C.OF (VAV cool mode off offset) offsets are used in
conjunction with the low heat mode off trip point to determine
when to bring cooling on and off and in enforcing a true "vent"
mode between heating and cooling. See Fig. 4. The occupied cool-
ing set point is not used in the determination of the cool mode. The
occupied cooling set point is used for supply air reset only.
OHSP
L.H.ON
DMDLHON
Fig. 4 — VAV Occupied Period Trip Logic
The advantage of this offset technique is that the control can
safely enforce a vent mode without worrying about crossing set
points. Even more importantly, under CCN linkage, the occu-
pied heating set point may drift up and down and as such this
technique of using offsets ensures a guaranteed separation in
degrees F between the calling out of a heating or cooling mode
at all times.
VAV Occupied Cool Mode Evaluation Configuration
There are VAV occupied cooling offsets under Setpoints.
Table 28 — Cooling Configuration (cont)
EXPANSION
Table 29 — Setpoints
EXPANSION
V.C. ON
V.C. OF
VAVOCON
VAVOCOFF
L.H.OF
a48-8414
DMDLHOFF
RANGE UNITS
–100 to 100
–200 to 200
0 to 1
1 to 1.5
2 to 15 °psig
0 to 5 °psig
400 to 450 psig
480 to 550 psig
6 to 150 sec
0 to 15 %
RANGE UNITS
40-99 dF
40-99 dF
40-99 dF
40-110 dF
2-10 ^F
0-25 ^F
1-25 ^F
45-75 dF
45-75 dF
45-75 dF
90-145 dF
–20-80 dF
5-75 dF
–20-80 dF
–20-80 dF
ITEM EXPANSION
V.C.ON VAV Occ.
Cool On Delta
V.C.OF VAV Occ.
Cool Off Delta
NOTE: There is a submenu at the local display (Run Status
 TRIP) that allows the user to see the exact trip points for
both the heating and cooling modes without having to calculate
them. Refer to the Cool Mode Diagnostic Help section on
page 51 for more information.
To enter into a VAV Occupied Cool mode, the controlling tem-
perature must rise above [OHSP minus L.H.ON plus L.H.OF
plus V.C.ON].
To exit out of a VAV Occupied Cool Mode, the controlling
temperature must fall below [OHSP minus L.H.ON plus
L.H.OF plus V.C.ON minus V.C.OF].
NOTE: With vent mode, it is possible to exit out of a cooling
mode during the occupied period if the return-air temperature
drops low enough. When supply-air temperature reset is not
configured, this capability will work to prevent over-cooling
the space during the occupied period.
Supply Air Set Point Control and the Staging of Compressors
Once the control has determined that a cooling mode is in ef-
fect, the cooling control point (Run Status  VIEW  CL.C.P)
is calculated and is based upon the supply air set point (Set-
points  SASP) plus any supply air reset being applied (In-
puts  RSET  SA.S.R).
Refer to the SumZ Cooling Algorithm section on page 51 for a
discussion of how the N Series ComfortLink controls manage
the staging of compressors to maintain supply-air temperature.
49
CCN POINT DEFAULT
EXV_SLP
EXV_INT
EXV_SMAL
ERR_POW
DP_RC_ST
DP_RC_CL
DP_OD_L1
DP_OD_L2
DP_OD_TO
DP_OD_PT
CCN POINT DEFAULT
OHSP
OCSP
UHSP
UCSP
HCSP_GAP
VAVOCON
VAVOCOFF
SASP
SASP_HI
SASP_LO
SASPHEAT
TEMPPURG
TEMPCOOL
TEMPVOCC
TEMPVUNC
CCN
RANGE UNITS
POINT
0 to 25 deltaF VAVOCON
1 to 25 deltaF VAVOCOFF
–0.4
66
0
1.3
10
1
400
500
90
10
68
75
55
90
5
3.5
2
55
55
60
85
50
5
65
50
DEFAULT
3.5
2