York MILLENNIUM Y22 Installation Manual Download Page 86

Page: 86 / 140

102777-YIM-E-0206

Unitary Products Group

Holiday Schedule

•

If the Start Time is programmed to zero, the default is all
day.

•

The Number of Days will be programmed from 0-99.

•

The Start Date is programmed by Month-Day-Year.

•

When the Start Date is 00-00-0000, that Holiday is
ignored.

•

When the Time is 00:00, the Time is equal to 12:00 a.m.,
the beginning of the day.

Full heating (all stages) is ON when RAT drops 2

F below the

setpoint, heating is OFF when RAT is at, or above the set-
point. (Note that in this case, the control will use all available
heating stages, regardless of setting of the programmable
parameter "Heat Stages"). Before energizing heat for Morn-
ing Warm Up the control will start the Fan and operate it for 5
minutes. The Economizer will stay closed and the Fan will
continue to run during the Morning Warm Up. The Morning
Warm Up will terminate when the Occupied period begins.

If the RAT setpoint is achieved before the MWU period
expires, Unoccupied cooling is permitted. If further heating is
needed during the Occupied period, it is controlled by a VAV
Occupied Heating algorithm (if enabled and if a Space Sen-
sor is used), or by a space thermostat.

The same algorithm is also used for VAV Occupied Heating
(see also paragraph "VAV Occupied heating" in "Option Oper-
ation" section earlier in this document). In this case, the VAV
Occupied Heating control algorithm is activated under the
control of the Space Sensor (whenever the zone temperature
sensed by the Space Sensor drops 2

F or more below a pro-

grammed "VAV SAT Reset Setpoint"). Once activated, the
Occupied Heating control algorithm controls RAT between
the MWU RAT Setpoint and two degrees below the setpoint
and cycles the fan the same way as the MWU algorithm.

The specified Max Morning Warm Up Time is not used to limit
the duration of VAV Occupied Heating. During heating for
Morning Warm Up, or for VAV Occupied heating function, the
VAV boxes controls will receive an override signal to open the
VAV box damper. This is accomplished by wiring the VAV
heat relay for the VAV boxes to open, and energizing it from
Heat output of the controller. Note that as the first stage of
heat cycles on / off, the VAV box heat relay will cycle with it.

UNOCCUPIED VAV HEATING / COOLING CONTROL
ALGORITHM WITH A SPACE SENSOR

In the unoccupied mode, the Space Sensor will compare the
temperature in a selected VAV zone to the programmed
Unoccupied Heating and Cooling setpoints and request heat-
ing or cooling using the following control algorithm:

OCCUPIED VAV HEATING / COOLING CONTROL ALGO-
RITHM WITH A SPACE SENSOR

In the occupied mode, the control will compare the tempera-
ture in a selected VAV zone to the programmed "VAV SAT
Reset Setpoint" and request heating or cooling using the fol-
lowing control algorithm: The transition from cooling to occu-
pied heating occurs at 2

F below the "VAV SAT Reset

Setpoint". There is no "satisfied", or "idle" state of the unit
between cooling and occupied heating.

The above algorithm only requests occupied cooling and
selects a SAT occupied cooling setpoint, or requests occupied
heating at a programmed "Morning Warm Up RAT Setpoint".

Once requested by this Space Sensor algorithm, the cooling
is controlled by the SAT control algorithm described in para-
graph "SAT Control Algorithm in VAV Cooling" earlier in this

TABLE 44: WEEKLY SCHEDULE

Times

Mon

Tues

Wed

Thu

Fri

Sat

Sun

Occupied 1

00:00 00:00 00:00 00:00 00:00 00:00 00:00

Unoccupied 1