York MILLENIUM SIMPLICITY ELITE Series Technical Application And Programming Manual page 33

UNOCCUPIED HEATING WITH A THERMOSTAT
This operation is identical to the Occupied heating, except the
unit mode is in Unoccupied mode from the internal control
Occupied/Unoccupied table. The economizer damper remains
fully closed in the unoccupied mode.
OCCUPIED COOLING WITH A THERMOSTAT
In this mode, the control uses a thermostat for cooling and fan
operation. The thermostat's occupied cooling setpoint should
be set below the zone thermostat's lowest adjustable cooling
setpoint, to prevent a possibility of cooling turned off while other
zone(s) in the system still have a cooling demand.
UNOCCUPIED COOLING WITH A THERMOSTAT
This operation is identical to the Occupied cooling, except when
operating in the unoccupied mode the control is programmed to
control to its unoccupied cooling setpoint and the economizer
damper min. position is set to 0%, however the damper may
modulate open if outdoor air can be used for free cooling
(economizer operation).
OCCUPIED HEATING WITH A SPACE SENSOR
The Space Sensor is placed in a selected, representative zone
of the VAV system, in addition to the zone thermostat, or sensor
used to control the zone's VAV box. The heating control
algorithm is enabled whenever the zone temperature drops 2 °F
or more below a programmed "VAV SAT Reset Setpoint", and
disabled whenever the zone temperature is 1.5 °F, or less
below a programmed "VAV SAT Reset Setpoint". The "VAV SAT
Reset Setpoint" would typically be set at, or below the lowest
zone temperature setpoint selectable on the zone thermostat.
The supply fan is controlled to 100% during occupied heating
and cycles OFF when the heating control algorithm is satisfied if
there is no other call for the fan. On startup, the fan speed is
ramped up, or the inlet vanes ramped open (a "soft start").
When a call for heating (W1 or W2=ON) occurs, the economizer
damper remains at its programmed minimum position and all
VAV boxes go fully open - box heat relays are energized from
Heat output of the controller.
If Hydronic heat option is used, the Heat output of the controller
is also actuated during heating and the SAT is controlled to the
2 stage hydronic heat setpoint.
nd
UNOCCUPIED HEATING WITH A SPACE SENSOR
When this mode is enabled and the unit enters the unoccupied
mode, the unit will control heating by comparing the zone
temperature to a programmed "Unoccupied Heating Setpoint".
The Space Sensor should be placed in a selected,
representative zone of the VAV system, in addition to the zone
thermostat, or sensor used to control the zone's VAV box.
Full heating (all heating stages ON) occurs when the Space
Sensor algorithm requests heating, no heating (all heating
stages OFF) when the Space Sensor algorithm is satisfied (note
that in this case, the control will use all available heating stages,
Johnson Controls Unitary Products
regardless of setting of the programmable parameter "Heat
Stages").
The supply fan is controlled to 100% during unoccupied heating
and cycles OFF when the Space Sensor control algorithm is
satisfied if there is no other call for the fan. On startup, the fan
speed is ramped up, or the inlet vanes ramped open (a "soft start").
During unoccupied heating, the economizer damper is fully
closed and all VAV boxes go fully open - box heat relays are
energized from Heat output of the controller.
OCCUPIED COOLING WITH A SPACE SENSOR
This mode is entered when the control sees a Space Sensor
signal and enters the "occupied" mode. The Space Sensor
requests cooling (to a programmed High, or Low SAT setpoint)
whenever the zone temperature increases by a specified
amount above a programmed "VAV SAT Rest Setpoint". The
Space Sensor should be placed in a selected, representative
zone of the VAV system, in addition to the zone thermostat, or
sensor used to control the zone's VAV box.
The "VAV SAT Reset Setpoint" would typically be set at, or
below the lowest zone temperature setpoint selectable on the
zone thermostat, in order to prevent a possibility of insufficient
cooling while other zone(s) in the system still have a high
cooling demand.
The supply fan, economizer, VAV boxes operate within their
normal control rules.
UNOCCUPIED COOLING WITH A SPACE SENSOR
In this mode, the Space Sensor requests cooling based on
comparing the zone temperature to a programmed
"Unoccupied Cooling Setpoint". When the Space Sensor control
algorithm requests cooling, the unit runs cooling controlled to a
programmed High SAT setpoint ("VAV Upper Cooling SAT
Setpoint"), or to a programmed Low SAT Setpoint ("VAV Upper
Cooling SAT Setpoint"), as determined by comparison of zone
temperature to a programmed "VAV SAT Reset Setpoint". The
"VAV SAT Reset Setpoint" would typically be set well below the
"Unoccupied Cooling Setpoint", causing the unoccupied cooling
to typically use a Low SAT Setpoint.
There are two different SAT control algorithms, one used when
free cooling is available (economizer operation) and the other
one for mechanical cooling only. These two SAT control
algorithms are described in the "Occupied Cooling in
Standalone Operation" section below. Since the economizer is
not active in Unoccupied mode, this will be restricted to
mechanical cooling.
UNOCCUPIED HEATING IN STANDALONE OPERATION
Unoccupied heating is never used in standalone operation.
OCCUPIED COOLING IN STANDALONE OPERATION
The unit controls cooling to a programmed Low SAT setpoint
("VAV Lower Cooling SAT Setpoint") during the occupied mode.
There are two different SAT control algorithms, one used when
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