The application function selects the HVAC plant operating mode (PltOpMod) and considers the room operating mode, presence detection, HVAC presence mode and window contact. Warmup and cool down request signals are received using the central operating system (e.g., Scheduler).

The VAV application templates support 17 different plant modes. The plant modes are provided to cover a wide variety of room applications.

NOTE:
If a specific plant mode is not used, it should not be enabled.

 

Enum
PltOpMod

Plant Mode

Purpose

Action of Mechanical Equipment

Trigger(s)

1

Off

Shutdown all heating, cooling and ventilation.

All mechanical equipment turns off.

manual command, or initial startup

2

Building Protection

Conserve energy in long term vacancy. To protect mechanical equipment from freezing or other adverse conditions.

 

manual command or schedule

 

 

3

Economy

Conserve energy during daily unoccupied period.

Night setback/setup during unoccupied hours. Ventilation reduced or off selected by configuration.

schedule/ occ sensor

4

Pre-Comfort

Conserve energy for brief unoccupied periods.

Configurable. Example: Shut off ventilation for conference rooms that are unoccupied during the normally occupied daytime hours.

schedule/ occ sensor

 

5

Comfort

Provide room air conditions suitable for room occupancy.

All space conditioning equipment runs in “automatic” to maintain desired space conditions during occupancy.

schedule/ occ sensor or comfort button from room operating unit

6

Warm-up

Return to comfort conditions before occupancy

Mechanical heating equipment starts before occupancy period begins. Comfort setpoints apply for temperature. Ventilation may be off.

central command

7

Cool-down

Return to comfort conditions before occupancy

Cooling equipment starts before occupancy period begins. Comfort setpoints apply for temperature. Ventilation may be off.

central command

8

Room temp. (frost) prot.

Avoid damage in room by applying heat at high priority, overriding errant commands from outside the application

not used in VAV

 

9

Equipment temperature protection

Avoid damage to equipment, such as frozen coils

not used in VAV

 

10

Free cooling

Overcool past current demand to store energy

Pre-cool building or zones beyond current setpoint during advantageous periods, storing energy in the thermal mass to reduce the need for cooling later.

central command

11

Night cooling

Prevent build-up of heat in interior spaces during unoccupied hours.

Cooling using 100% outside air during night time.

central command

12

Rapid ventilation

Clear contaminated air with temporary high primary airflow

Supply air flow goes to the max ventilation value. Temp control continues according to room op mode.

manual command from room unit

14

Fire (EmgOff)

Isolate fire and smoke, preventing spread through the ventilation system

Supply air damper closes. Exhaust air damper closes.

External command to fire mode object.

15

Smoke Positive press.

Oppose infiltration of smoke to room from surrounding spaces

Supply flow goes to a configured level. Extract damper closes.

External command to fire mode object.

16

Smoke Negative press.

Oppose exfiltration of smoke from room to surrounding spaces

Extract flow goes to a configured level. Supply damper closes,

External command to fire mode object.

17

Smoke Purge

Clear smoke from the building after a fire

Supply flow goes to largest of configured limits. Extract tracks normally.

External command to fire mode object.

The Table below shows the different room and central BAS functions that determine the plant mode for the VAV application templates.

NOTE:
If an input is not configured in the application, it is NOT USED in determining the plant mode state.

IF

THEN

Room operating mode

 

Presence detection

 

(Room Comfort Button)

Window contact

 

 

(Room)

Night cooling signal

 

(from Scheduler)

Cool down signal

 

(from Scheduler)

Warm-up signal

 

(from Scheduler)

Plant mode

-

-

Open

-

-

-

Protection

Protection

-

Closed

-

-

-

Protection

Economy

-

Closed

False

False

False

Economy

-

Closed

True

False

False

Night cooling

-

Closed

-

-

True

Warm-up

-

Closed

-

True

False

Cool down

Pre-Comfort

-

Closed

-

True

-

Cool down

-

Closed

-

False

-

Pre-Comfort

Present

Closed

-

-

-

Comfort

Absent

Closed

-

False

-

Pre-Comfort

Absent

Closed

-

True

-

Cool down

Comfort

-

Closed

-

-

-

Comfort

Present

Closed

-

-

-

Comfort

Absent

Closed

-

False

-

Pre-Comfort

Absent

Closed

-

True

-

Cool down

 

Present

Closed

-

-

-

Rapid Ventilation