Carrier 48FC Series Controls, Start-Up, Operation And Troubleshooting page 14

DEMAND
EMERGENCY
SAFETY FAULT
SERVICE TEST
SHUTDOWN
NO DEMAND
FAN ONLY
DEHUM
LOW COOL
HIGH COOL
LOW COOL & DEHUM
HIGH COOL & DEHUM
UFC LOW COOL
UFC HIGH COOL
LOW HEAT
HIGH HEAT
SUPPLY AIR TEMPERING
Thermostat Inputs
Y1 Y2
0 0
0 1
1 0
1 1
Set the LOW COOL COMP as needed.
*
Table 10 – Thermostat Heating System Demands
Thermostat Input
W1 W2
0 0 No Heat
0 1 Alert & Low Heat
1 0 Low Heat
1 1 High Heat
Space Sensor Demand
When the unit control type is configured for space sensor (UNIT
CONTROL TYPE = SPACE SEN) the level 5 demand in Table 8
will be determined by the space sensor inputs and setpoints as
described below. The Effective Demand Temperature (DEMAND
CTRL TEMP) represents the temperature which the control is
using to control the space. This would come from the space sensor,
building network, linkage, or the return air sensor.
Setpoint Determination
Setpoints are used to control the unit. The Cool Setpoint in Effect
(EFF COOL SETPOINT) and the Heat Setpoint in Effect (EFF
HEAT SETPOINT) are the points in which the unit is controlling
to at a specific time. These points are read only points and change
according to occupancy, the offset slider status, and network writes.
The setpoint configurations are in the SETTINGSSPACE SET
POINTS submenu.
If the building is in occupied mode, the Occupied Cool Setpoint
(OCC COOL SETPOINT) and the Occupied Heat Setpoint (OCC
HEAT SETPOINT) are active. When the building is in
unoccupied mode, the Unoccupied Cool Setpoint (UNOCC COOL
SETPNT) and the Unoccupied Heat Setpoint (UNOCC HEAT
SETPNT) are active. The heating and cooling set points are also
separated by a Heat- -Cool Set Point Gap (HEAT- COOL SP GAP)
that is user configurable from 2 to 10 degrees F. This parameter
will not allow the setpoints to be set too close together, it will
change the last setpoint adjusted if it is set within the GAP.
Table 8 – Demand List and Priority
Priority
1 An emergency condition occurs which requires a unit shutdown
2 A safety diagnostic requires the unit to run in safety mode.
3 User request test mode
4 A minor or user condition requires the unit to shutdown
There is no comfort demand from the building
Only circulation or ventilation is requested form the building
A dehumidification load is present in the building
A low cooling load is present in the building
A high cooling load is present in the building
A low cooling and dehumidification load is present in the building
5
A high cooling and dehumidification load is present in the building
A low cooling load is present in the building due to the unoccupied free cooling algorithm
A high cooling load is present in the building due to the unoccupied free cooling algorithm
A low heating load is present in the building
A high heating load is present in the building
Due to outside air, supply air is uncomfortably cool during ventilation
Table 9 – Thermostat Cooling System Demands
CONV 2C2H*
No Cool
Alert & Low Cool
Low Cool
High Cool
THERMOSTAT TYPE
CONV 2C2H DIGI 2C2H
CONV 3C2H DIGI 3C2H
No Heat
High Heat
Low Heat
High Heat
Description
THERMOSTAT TYPE
CONV 3C2H
No Cool
Alert & Low Cool
Low Cool
High Cool
When the space sensor has a setpoint slider adjustment, the cool
and heat setpoints (occupied) can be offset by sliding the bar from
one side to the other. The SPT Offset Range (+/- -) (SPT SLIDER
RANGE) sets the total positive or negative degrees that can be
added to the setpoints. With the slider in the middle, no offset is
applied. Moving the slider to the "COOL" side will subtract from
each setpoint, and sliding it to the "WARM" side will add to the
setpoints. The slider offset being applied at any given time is
displayed as Space Temperature Offset (SLIDER OFFSET VAL).
Temperature Demand
Space sensor staging control is an adaptive anticipation control that
weighs the actual space demand against the trend of that demand.
The control tries to anticipate the change in the space because of its
current stage status. This anticipation is based on the demand
trends. These trends will show the control how the space is reacting
to the current running conditions and help it decide when to
change the actual demand of the system. The following points are
in the RUN STATUSMODE submenu:
COOLING DEMAND — This is the difference between the Cool
Setpoint in Effect (EFF COOL SETPOINT) and the Effective
Demand Temperature (DEMAND CTRL TEMP) representing the
demand of the space for cooling.
COOL DEMAND TREND — This is the rate of change of the
cooling demand in degrees per minute, representing how the space
is changing its demand for cooling.
HEATING DEMAND — This is the difference between the Heat
Setpoint in Effect (EFF HEAT SETPOINT) and the Effective
Demand Temperature (DEMAND CTRL TEMP) representing the
demand of the space for cooling.
HEAT DEMAND TREND — This is the rate of change of the
heating demand in degrees per minute, representing how the space
is changing its demand for cooling.
In general the system demand will increase based on the demand
compared to the demand switch states in Fig. 9. The demand
cannot increase until Time guard 1 (DEMAND TIMEGUARD1)
expires. The LCON and LHON thresholds will also cause the
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DIGI 2C2H DIGI 3C2H
No Cool
High Cool High Cool
Low Cool Low Cool
High Cool High Cool
No Cool