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51
Table 30 —
Cool/Heat Set Point Offsets Configuration
C.TYP = 3 (Thermostat Cool Mode Selection)
When a thermostat type is selected, the decision making process
involved in determining the mode is straightforward. Upon ener
-
gizing the Y1 input only, the unit HVAC mode will be LOW
COOL. Upon the energizing of both Y1 and Y2 inputs, the unit
HVAC mode will be HIGH COOL. If just input G is energized,
the unit HVAC mode will be VENT and the supply fan will run.
Selecting the
C.TYP
= 3 (TSTAT – MULTI) control type will
cause the control to do the following:
• The control will read both the
Configuration
UNIT
SIZE
and
Configuration
UNIT
50.HZ
configuration
parameters to determine the number of cooling stages and
the pattern for each stage.
• An HVAC mode equal to LOW COOL will cause the unit to
control to the
Setpoints
SA.LO
set point. An HVAC mode
equal to HIGH COOL will cause the unit to control to the
Set
-
points
SA.HI
set point. Supply air reset (if configured) will
be added to either the low or high cool set point.
• The control will utilize the SumZ cooling algorithm and
control cooling to a supply air set point. See the section for
the SumZ Cooling Algorithm section for information on
controlling to a supply air set point and compressor staging.
COOL MODE DIAGNOSTIC HELP
To quickly determine the current trip points for the cooling modes,
the Run Status submenu at the local display allows viewing of the
calculated start and stop points for both the cooling and heating
trip points. The following submenu can be found at the local dis
-
play under
Run Status
TRIP
.
See
Table 31 —
Run Status Mode Trip Helper
The controlling temperature is “
TEMP
” and is in the middle of
the table for easy reference. The HVAC mode can also be
viewed at the bottom of the table.
For non-linkage applications and VAV control types (
C.TYP
=
1 or 2), “TEMP” is the controlling return air temperature
(
R.TMP
). For space sensor control, “TEMP” is the controlling
space temperature (
S.TMP
). For linkage applications, “TEMP”
is zone temperature:
AOZT
during occupied periods and
AZT
during unoccupied periods.
SUMZ COOLING ALGORITHM
The SumZ cooling algorithm is an adaptive PID (proportional,
integral, derivative) that is used by the control whenever more
than 2 stages of cooling are present (
C.TYP
= 1,2,3, and 4). This
section will describe its operation and define the pertinent pa
-
rameters. It is generally not necessary to modify parameters in
this section. The information is presented for reference and may
be helpful for troubleshooting complex operational problems.
The only configuration parameter for the SumZ algorithm is
located at the local display under
Configuration
COOL
Z.GN
.
See Table 28.
Capacity Threshold Adjust (Z.GN)
This configuration affects the cycling rate of the cooling stages
by raising or lowering the threshold that capacity must build to
in order to add or subtract a stage of cooling.
The cooling algorithm’s run-time variables are located at the
local display under
Run Status
COOL
.
Current Running Capacity (C.CAP)
This variable represents the amount of capacity currently run
-
ning in percent.
Current Cool Stage (CUR.S)
This variable represents the cool stage currently running.
Requested Cool Stage (REQ.S)
This variable represents the requested cool stage. Cooling relay
timeguards in place may prevent the requested cool stage from
matching the current cool stage.
Maximum Cool Stages (MAX.S)
This variable is the maximum number of cooling stages the
control is configured for and capable of controlling.
Active Demand Limit (DEM.L)
If demand limit is active, this variable will represent the
amount of capacity that the control is currently limited to.
Capacity Load Factor (SMZ)
This factor builds up or down over time and is used as the
means of adding or subtracting a cooling stage during run time.
It is a normalized representation of the relationship between
“Sum” and “Z”. The control will add a stage when
SMZ
reach
-
es 100 and decrease a stage when
SMZ
equals -100.
Next Stage EDT Decrease (ADD.R)
This variable represents (if adding a stage of cooling) how
much the temperature should drop in degrees depending on the
R.PCT
calculation and exactly how much additional capacity
is to be added.
ADD.R
=
R.PCT
*
(
C.CAP
— capacity after adding a cooling
stage)
For example: If
R.PCT
= 0.2 and the control would be adding
20% cooling capacity by taking the next step up, 0.2 times 20 =
4°F (
ADD.R
)
ITEM
EXPANSION
RANGE
UNITS
CCN POINT
DEFAULT
D.LV.T
COOL/HEAT SETPT. OFFSETS
L.H.ON
Dmd Level Lo Heat On
0 to 2
^F
DMDLHON
1.5
H.H.ON
Dmd Level(+) Hi Heat On
0.5 to 20.0
^F
DMDHHON
0.5
L.H.OF
Dmd Level(-) Lo Heat Off
0.5 to 2.0
^F
DMDLHOFF
1
L.C.ON
Dmd Level Lo Cool On
0 to 2
^F
DMDLCON
1.5
H.C.ON
Dmd Level(+) Hi Cool On
0.5 to 20.0
^F
DMDHCON
0.5
L.C.OF
Dmd Level(-) Lo Cool Off
0.5 to 2
^F
DMDLCOFF
1
C.T.LV
Cool Trend Demand Level
0.1 to 5
^F
CTRENDLV
0.1
H.T.LV
Heat Trend Demand Level
0.1 to 5
^F
HTRENDLV
0.1
C.T.TM
Cool Trend Time
30 to 600
sec
CTRENDTM
120
H.T.TM
Heat Trend Time
30 to 600
sec
HTRENDTM
120
ITEM
EXPANSION
UNITS
CCN
POINT
TRIP
MODE TRIP HELPER
UN.C.S
Unoccup. Cool Mode Start
dF
UCCLSTRT
UN.C.E
Unoccup. Cool Mode End
dF
UCCL_END
OC.C.S
Occupied Cool Mode Start
dF
OCCLSTRT
OC.C.E
Occupied Cool Mode End
dF
OCCL_END
TEMP
Ctl.Temp R.TMP,S.TMP or Zone
dF
CTRLTEMP
OC.H.E
Occupied Heat Mode End
dF
OCHT_END
OC.H.S
Occupied Heat Mode Start
dF
OCHTSTRT
UN.H.E
Unoccup. Heat Mode End
dF
UCHT_END
UN.H.S
Unoccup. Heat Mode Start
dF
UCHTSTRT
Summary of Contents for WeatherExpert 48N2
Page 135: ...135 Fig 18 48 50N Typical Power Schematic Nominal 075 Ton Unit Shown ...
Page 136: ...136 Fig 19 48 50N Typical Power Schematic Nominal Ton 90 150 Units Shown ...
Page 137: ...137 Fig 20 48 50N Main Base Board Input Output Connections ...
Page 138: ...138 Fig 21 48 50N RXB EXB CEM Input Output Connections a48 9307 ...
Page 139: ...139 Fig 22 48 50N EXV SCB Input Output Connections a48 9308 ...
Page 140: ...140 Fig 23 48N Typical Modulating Gas Heat Unit Control Wiring ...
Page 141: ...141 Fig 24 50N Typical Electric Heat Unit Control Wiring ...
Page 144: ...144 Fig 27 48N Typical Gas Heat Section Wiring Nominal Ton 120 to 150 Units ...
Page 145: ...145 Fig 28 48 50N Typical Power Component Control Wiring 460 v ...
Page 146: ...146 Fig 29 48 50N Component Control Wiring 575 v Nominal Ton 075 to 150 Units ...
Page 147: ...147 Fig 30 48 50N Component Arrangement Power Box ...
Page 148: ...148 Fig 31 48 50N Component Arrangement Control Box ...
Page 240: ...240 APPENDIX D VFD INFORMATION CONT Fig G VFD Bypass Wiring Diagram WHEN USED ...