Unit installation

14
Heat OAT Lockout (H.LOC)
Displays if heating operation is prevented due to outdoor
temperature limit lockout.
Econo Cool OAT Lockout (E.LOC)
Displays if economizer operation for cooling is prevented due to
outdoor temperature limit lockout.
General Operation
48/50LC units can provide cooling, dehumidification, heating, and
ventilation operation. Each unit will operate under one of two
basic types of control: thermostat or space temperature sensor.
There are many inputs, configurations, safety factors, and
conditions that ultimately control the unit. Refer to the specific
operation sections for detail on a specific unit operation.
When thermostat control is enabled (Configuration→UNIT
→U.CTL = 1), the unit will operate based on discrete input
commands (G, Y1, Y2, W1, and W2) and there is a one minute
time delay between modes and when re--entering a mode. The G
command calls for ventilation, the Y1 and Y2 commands call for
cooling, and the W1 and W2 commands call for heating.
Thermostat Control Type (Configuration→UNIT→T.CTL) affects
how cooling operates based on Y1 and Y2 commands and if
cooling/heating stage time guards are applied.
When space temperature sensor control is enabled (Configuration
→UNIT→U.CTL = 2), the unit will try to maintain the Space
Temperature (Temperatures→AIR.T→SPT) between the effective
cool and heat setpoints (Run Status→MODE→EFF.C and
EFF.H). However, to minimize unnecessary cool to heat and heat
to cool changes, there is a 10 minute delay after the last stage turns
off before the control will switch modes and a 1 minute delay when
re--entering the last mode. Linkage operation overrides the mode
changeover delay to 15 seconds. The cooling and heating Mode
Select Timeguard (Operating Modes→COOL→MS.TG and
Operating Modes→HEAT→MS.TG) show the remaining time
before allowing the respective mode to be entered.
Temperature Setpoint Determination
Setpoints are used to control the unit while under space
temperature sensor control. The Cool Setpoint in Effect (EFF.C)
and the Heat Setpoint in Effect (EFF.H) 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 (Linkage or LON).
If the building is in occupied mode, the Occupied Cool Setpoint
(Setpoints→OCSP) and the Occupied Heat Setpoint (Setpoints
→OHSP) are active. When the building is in unoccupied mode,
the Unoccupied Cool Setpoint (Setpoints→UCSP)andthe
Unoccupied Heat Setpoint (Setpoints→UHSP) are active. The
heating and cooling set points are also separated by a Heat--Cool
Set Point Gap (Setpoints→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.
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 (+/--) (Setpoints
→STO.R) 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 (Temperatures→AIR.T
→SPTO).
Occupancy Determination
The building’s occupancy is affected by a number of different
factors. When the unit is operating with a space temperature sensor
(T--55, T--56, T--58 or T--59), occupancy affects the unit set points
and the operation of the economizer. If the unit is operating under
thermostat control, occupancy only affects the operation of the
economizer. If using a relative humidity sensor, then occupancy
will affect the RH setpoints. The factors affecting occupancy are
listed below from highest to lowest priority.
Level 1 Priority
Level 1 classification is a force/write to occupancy and can occur three
ways. Listed in order of priority: force on OCCUPIED, a write to
NVI_OCC, and a Linkage write. The CCN point OCCUPIED is
forced via an external device such as a ComfortIDt controller or a
service tool. When OCCUPIED is forced to YES, the unit is
considered occupied, when OCCUPIED is forced to NO, the unit is
considered unoccupied. If the 3rd party protocol LON is writing to
NVI_OCC, the control maps it to OCCUPIED as an input. If the unit
is being controlled by Linkage, the occupancy is communicated and
mapped to OCCUPIED as an input. LON and Linkage do not force
the point, only write to it, therefore a force applied to OCCUPIED
will override them.
If OCCUPIED is not being forced or written to, proceed to the
level 2 priority.
Level 2 Priority
Remote Occupancy Switch should be configured to either
Normally Open or Normally Closed when the user would like to
control the occupancy with an external switch. This switch is
field--supplied (24v, single pole, single throw [SPST]). There are
three possible configurations for the remote occupancy switch:
1. (Configuration→UNIT→RM.SW = 0) No Switch
2. (Configuration→UNIT→RM.SW = 1) Normally Open
Switch
3. (Configuration→UNIT→RM.SW = 2) Normally Closed
Switch
If the switch is configured to No Switch (0), the switch input value
will be ignored and software will proceed to level 3 priority. For
each type of switch, the appropriate configuration and states are
listed in the table below. The Remote Occupancy Switch
(INPUTS→GEN.I→RM.OC) point will show the status of the
switch.
TYPE OF SWITCH
SWITCH
CONFIGURATION
STATE OF SWITCH
AND STATE OF
OCCUPANCY
Occupied when Closed
or Unoccupied when
Open
Normal Open (1)
Open and Unoccupied
Closed and Occupied
Occupied when Open or
Unoccupied when
Closed
Normal Closed (2)
Open and Occupied
Closed and Unoccupied
NOTE: To perform remote occupancy, an Economizer Control
Board must be installed in the unit.
48/50LC