Carrier WeatherExpert 48N2 Controls, Start-Up, Operation, Service, And Troubleshooting page 51

ITEM
D.LV.T COOL/HEAT SETPT. OFFSETS
L.H.ON Dmd Level Lo Heat On
H.H.ON Dmd Level(+) Hi Heat On
L.H.OF Dmd Level(-) Lo Heat Off
L.C.ON Dmd Level Lo Cool On
H.C.ON
Dmd Level(+) Hi Cool On
L.C.OF Dmd Level(-) Lo Cool Off
C.T.LV Cool Trend Demand Level
H.T.LV Heat Trend Demand Level
C.T.TM Cool Trend Time
H.T.TM Heat Trend Time
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.
Table 31 — Run Status Mode Trip Helper
ITEM EXPANSION
TRIP MODE TRIP HELPER
UN.C.S Unoccup. Cool Mode Start
UN.C.E
Unoccup. Cool Mode End
OC.C.S Occupied Cool Mode Start
OC.C.E Occupied Cool Mode End
TEMP Ctl.Temp R.TMP,S.TMP or Zone
OC.H.E Occupied Heat Mode End
OC.H.S Occupied Heat Mode Start
UN.H.E
Unoccup. Heat Mode End
UN.H.S Unoccup. Heat Mode Start
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.
Table 30 — Cool/Heat Set Point Offsets Configuration
EXPANSION
CCN
UNITS
POINT
dF UCCLSTRT
dF UCCL_END
dF OCCLSTRT
dF OCCL_END
dF CTRLTEMP
dF OCHT_END
dF OCHTSTRT
dF UCHT_END
dF UCHTSTRT
RANGE UNITS
0 to 2 ^F DMDLHON
0.5 to 20.0 ^F DMDHHON
0.5 to 2.0 ^F DMDLHOFF
0 to 2 ^F DMDLCON
0.5 to 20.0 ^F DMDHCON
0.5 to 2 ^F DMDLCOFF
0.1 to 5 ^F CTRENDLV
0.1 to 5 ^F HTRENDLV
30 to 600 sec CTRENDTM
30 to 600 sec HTRENDTM
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
 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. See Table 32.
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)
51
CCN POINT DEFAULT
1.5
0.5
1
1.5
0.5
1
0.1
0.1
120
120
display under Configuration