Building Control(Field Installed)

Application Specific / Zone Controller

Variable Volume/Variable Temperature (VVT)
Comfort System Guide Specifications (Controls)

2.1.7Zone Controller

2.1.7.1Variable Volume/Variable Temperature (VVT) Comfort System:
The VVT Comfort System shall consist of a programmable, multiple-zone communicating Monitor thermostat; multiple Zone Controllers; and a Bypass Controller. The system shall also include a complete array of input and output devices. The system shall provide full control of HVAC heating and cooling equipment in a multiple zone application. The VVT Comfort System shall be capable of operating as a stand-alone system or networked with multiple systems connected on a communications bus.

A.Products and Capabilities:
The control system shall be available as a complete package with the required input sensors and devices readily available. The system shall be capable of providing complete control of HVAC functions; variable air zone control, bypass air control in both pressure dependent and pressure independent applications. Airside controls shall be capable of operating VVT Comfort System dampers as well as VAV terminal boxes and Fan Powered terminal boxes with and without supplemental heat sources at the zone. Unit control relay packs shall be available factory mounted with direct connection to field-installed Monitor thermostats.
All temperature sensors shall be capable of being read and displayed in .1°F increments. Controllers shall have an on board LCD display capable of displaying sensor and input information applicable to the controller in degrees Fahrenheit or Celsius. The LCD shall be capable of displaying the following information as a minimum:
VVT Monitor

  • Space Temperature
  • DX Coil Temperature
  • Remote Room Sensor(s)
  • Indoor Relative Humidity
  • Space Temperature Averaging
  • Filter Status
  • System Indoor Air Quality Condition
  • Fan Status
  • Supply Air Temperature
  • Outside Air Temperature
    Zone Controller
  • Space Temperature
  • CFM
  • Remote Room Sensor(s)
  • Zone Indoor Air Quality Condition
  • Space Temperature Averaging
  • Zone Supply Air Temperature
    Bypass Controller
  • System Indoor Air Quality Condition
  • Remote Zone Sensor(s) (display only)
  • Space Temperature (display only)
  • Space Temperature Averaging (display only)
    All applicable sensors shall be accessed for calibration at the controller display.
  1. Controller Relay Interface:
    The relay board shall interface with the Monitor thermostat to provide staging control of heating and cooling and to provide sensor information to the controller. The relay board shall maintain constant data retrieval from the Monitor thermostat without interruption.
  2. Memory and Time Clock:
    The system shall not require the use of batteries for any data storage. The VVT Monitor, Zone Controller and Bypass Controller shall have a Non-Volatile Memory indefinite storage of configuration data. The VVT Monitor shall have, as an option, an on-board 365-day time clock with built in daylight savings time and leap year adjustment. In the event of power failure, the time clock shall be backed up. The VVT Monitor shall be capable of sharing time information with other VVT Comfort System controls or any other General Purpose Electronic Controller (see section 2.1.2 of this Guide Specification) existing on the communications bus with time clock capabilities. The VVT Monitor shall have the capability of changing occupancy mode by reading a set of discrete, dry contacts controlled by an external time clock.
  3. Setpoints:

A.The VVT Monitor and Zone Controller shall utilize and store the following setpoints:

  • Occupied Heating Setpoint
  • Occupied Cooling Setpoint
  • Unoccupied Heating Setpoint
  • Unoccupied Cooling Setpoint
  • Cooling Setpoint Low Limit
  • Heating Setpoint High Limit

B.The Monitor shall utilize and store these additional setpoints:

  • Heat Mode Error Setpoint
  • Cool Mode Error Setpoint
  • Heating OAT Lockout Setpoint
  • Cooling OAT Lockout Setpoint
  • Leaving Air High/Low Temperature Limits

C.Zone Controllers with the pressure independent control feature shall utilize and store these additional setpoints:

  • Minimum Airflow Setpoint
  • Maximum Airflow Setpoint

D.Bypass Controllers shall utilize and store these setpoints:

  • System Pressure Setpoint
  • IAQ Pressure Setpoint
  • Cool Down Setpoint
  • Warm Up Setpoint
    All setpoints shall be capable of being modified at the controller display or through a communication network with a PC and EMS software.
  1. Scheduling:
    The system shall be capable of operating in an occupied or unoccupied mode with up to 8 period changes per day. All VVT Monitors and Zone Controllers shall have the capability to follow independent schedules or receive the schedule from other VVT Comfort System products as well as all General Purpose Electronic Controllers (GPECs) existing on the communications bus with scheduling capabilities. All schedules shall be adjustable in one minute increments. The VVT Monitor shall be capable of utilizing up to 18 holiday schedules with up to 99 days per schedule for overriding the occupancy schedule.
    The VVT Monitor and Zone Controller shall have built-in override capabilities for unoccupied schedule override from 0 to 4 hours in 1 hour increments.
  2. Security Level:
    The VVT Monitor, Zone Controller and Bypass Controller shall have four levels of security for access of control tasks and decisions with level one providing full access and level four providing zero access from the controller display. Levels two and three provide limited access.
  3. HVAC Equipment Protection:
    The VVT Monitor shall be capable of monitoring the leaving air temperature as a safety device to limit the HVAC unit in both the heating and cooling modes. It shall have the capability to shut down stages based on a rise or fall in leaving air temperature above or below the configurable high and low safety limits. The system shall provide protection from the HVAC unit being intermittently cycled from heating to cooling or vice versa by utilizing time guard and minimum run time configurations. The Monitor shall have the capability of overriding all zone dampers to the open position in the event of a unit gas valve being stuck in the open position.
  4. Sensor Calibration:
    All applicable sensors shall be accessed for calibration at the controller or through a communicating network with a PC and EMS software.
  5. Energy Conservation:
    The system shall incorporate the following features for the provision of energy conservation:

A.Optimized Staging shall allow the VVT Monitor to monitor space temp demands and delay second stage of heating or cooling, if demands are being satisfied with single stage equipment.

B.The locking out of mechanical heating or cooling modes based on configurable outside air temperature limits.

C.The system shall intelligently start all equipment in a stagger start manner after a transition from unoccupied to occupied modes as well as power failure to reduce high peak power consumption on start up.

D.VVT controllers shall have the capability of being overridden by a Peak Demand Limiting Option Module (see Loadshed Software, under Global Network Programs, section 2.2.2. of this Guide Specification) existing on the communications bus with demand limiting functions to reduce overall energy consumption and control on and off peak time kW usage

  1. Stand Alone Capability:
    The controllers shall be capable of providing all control functions of the HVAC system without the use of a computer. All configuration selections shall be capable of being performed at the controller’s display via push button access.
    The controllers shall include the inherent capability to access the system control selections as well as to monitor system performance by means of a communicating network with a PC and EMS software program.
  2. DDC Control Networking:
    The VVT Comfort System controllers shall be capable of sharing the same communication network as all General Purpose Electronic Modules (see section 2.1.2 of this Guide Specification.) and option modules (e.g., Peak Demand Limiting, AutoDial Gateway, Data Collection. See Section 2.3, Global Network Programs).
    The VVT Monitor shall be capable of broadcasting time, date and outside air temperature on the communications bus to other VVT, Temperature System Unitary Controllers, and General Purpose Electronic Controllers (see section 2.1.2 of this Guide Specification.) existing on the network. The VVT Monitor shall also be able to receive this information and more from the same type of controllers on the network communications bus.
    The VVT Comfort System controllers shall also be capable of receiving commands from General Purpose Electronic Controllers (GPEC) existing on the communications bus. This information shall be used in a variety of ways to control the HVAC system as well as other building functions and applications.
  3. VVT Monitor:
    The VVT Monitor shall be capable of controlling space demand in a variable volume application by monitoring space temperature and determining the heating or cooling demand. The space temperatures shall be controlled to maintain individual heating and cooling setpoints. The VVT Monitor shall have the capability of operating in two modes, Scanning-Control Mode and Monitor-Only Mode. Scanning-Control Mode shall allow the Monitor to serve as a temperature zone in the system as well as providing all HVAC control. Monitor-Only mode shall allow the Monitor to perform system HVAC control without participating in zone temperature control.
    The VVT Monitor shall include system mode switches (Cool, Heat and Fan) for selecting the mode of control. These switches shall be used directly or overridden through configuration. The system fan shall be capable of operating in a continuous or automatic mode during occupied hours and in an automatic mode during unoccupied hours. The Monitor shall be capable of operating the system in manual or automatic change-over mode.
    The Monitor shall be capable of providing a communication check of all associated controls and display device type as well as error conditions.
  4. VVT Zone Controller:
    The VVT Zone Controller shall be capable of independent zone control when used with the VVT Monitor.
    The Zone Controller shall operate all VVT zone dampers as well as VAV and fan powered terminal boxes equipped with VVT damper actuators.
    The Zone Controller shall be capable of controlling supplemental heat or auxiliary heat sources, including fan control, when required at the zone level. Conversion to supplemental heat shall not require replacement of the control system.
    The Zone Controller shall operate in a pressure independent mode. Damper inlet area shall be adjustable in increments of one square inch. The Zone Controller shall be capable of reading zone airflow in CFM and controlling zone airflow based upon this information when operating in pressure independent mode.
    If a pressure dependent system Is being proposed remove the above paragraph and replace it follows: The Zone controller shall operate in a pressure dependent mode, Delete this note.
    The Zone Controller shall have an independent, programmable ventilation damper position capable of providing ventilation to the zone at all times. The ventilation operation shall have the ability to terminate if supply air temperature is out of bounds of set limits.
    The Zone Controller shall have the capability to support adjustable minimum and maximum damper positions.
  5. VVT Bypass Controller:
    The VVT Bypass Controller shall be capable of reading supply static pressure and controlling the bypass damper to maintain the supply static setpoint. This operation shall be provided when operating within a VVT Comfort System application or in a stand-alone mode.
    The Bypass Controller shall include an automatic heating/cooling mode temperature change-over cycle with adjustable setpoints to eliminate zone thermal shock during periods of system mode change.
    The Bypass Controller shall include a pre-positioning mode for opening the damper prior to fan operation. The Bypass Controller shall provide configurable minimum and maximum damper position settings.
    The Bypass Controller shall have the capability of displaying system static pressure, duct temperature, pressure setpoint and damper position.
    The Bypass Controller shall provide a system-setup feature to allow the installing contractor the ability to preset all associated dampers in the system for airflow balancing and pressure setup.
    The Bypass Controller shall provide the capability of increasing the maintained supply static pressure when the System, is in an IAQ mode.
  6. IAQ (If required by the I/O Summary and/or Sequence of Operation):
    The VVT Comfort System shall be capable of performing three modes of IAQ (Indoor Air Quality) by reading a discrete dry contact from a CO2 sensor or other sensors measuring volatile contaminants and provide demand ventilation IAQ through the economizer. Through the use of a GPEC and a communications bus, the system IAQ parts per million value shall have the capability of being read.

A.System IAQ (System Level):
The Monitor or Bypass Controller shall have the ability to read the IAQ status from the sensor. When the CO2 sensor, or another sensor reading volatile contaminants, exceeds the preset level, the Monitor shall energize the indoor fan motor (if not presently running). The Monitor after a predetermined time delay will energize the auxiliary relay for the economizer or exhaust fan, as applicable, to introduce fresh air into the building. The Monitor shall communicate the system IAQ status to all associated zones. Any zone configured to follow system IAQ shall open their respective damper after an initial time delay.
Individual zones shall be capable of locking out system IAQ participation through configuration. System heating and cooling shall be allowed to operate during a system IAQ mode.
All zones participating in system IAQ shall be capable of resetting their cooling and heating setpoint to a configurable value 0 to ±10°F to circulate outside air before the heating or cooling mode is initiated. Outside of these maximum space temperature reset setpoints, for zones participating in system IAQ, the IAQ damper mode shall be capable of being overridden locally.

B.Mode 2 — Local IAQ (Zone Level):
All VVT Comfort System Zone Controllers shall be capable of reading a dry contact from a CO2 sensor or other sensors measuring volatile contaminants at the zone level, for independent IAQ mode operation. The Zone Controller shall be capable of communicating a request for outside air to the Monitor in a zone IAQ condition. Upon receiving the IAQ request, the Monitor shall energize the indoor fan motor (if not presently running). The Monitor, after a pre-determined time delay shall energize the auxiliary relay (intended for economizer, but can be used for exhaust fan) to introduce fresh air into the zone.
All zones participating in local IAQ shall be capable of resetting their cooling and heating setpoint to a configurable value, 0 to ± 10°F, to circulate outside air before the heating or cooling mode is initiated.
System heating and cooling shall be allowed to operate during a local IAQ mode.
All VVT Comfort System Zone Controllers shall be capable of locking out local IAQ under the following conditions:

  • Outdoor humidity too high
  • Outdoor air temperature too high
  • Outdoor air temperature too low
    During a local IAQ mode, all zones participating in local IAQ shall be capable of overriding IAQ damper mode through configurable IAQ maximum space temperature reset configurations checking for extreme temperature deviation from setpoint in the zone.

C.Mode 3 — Pre-Occupancy Purge:
The VVT Comfort System shall be capable of providing a pre-occupied purge to flush the building of contaminants up to one hour before the occupancy period.
The IAQ sensor shall be available in wall-mount as well as duct-mount with an LED display of parts per million of measured contaminant. The setpoint shall be adjustable.

  1. Diagnostics:
    The controllers shall provide self-test, on board diagnostics and error code displays, and shall be capable of performing diagnostics on its critical components as well as all hard wired sensors and inputs. The controllers shall display any error messages on the LCD display until the error has been corrected or the error code display has been configured off. The controllers shall store the last five errors existing in the system for diagnostic monitoring. All errors shall be capable of being read from the controller through the use of a communicating network with a PC and EMS software.
  2. Monitoring:
    The VVT Comfort System controllers shall be capable of providing the following information for monitoring of system parameters:
  • Space Temperatures
  • Filter Status
  • Remote Space Temperatures
  • IAQ Status
  • Space Temperature Averaging
  • Occupancy Mode
  • Supply Air Temperatures
  • Leaving Air Temperature Conditions
  • DX Coil Temperature
  • Heat/Cool Mode Conditions
  • Return Air Temperature
  • Optimized Staging
  • Indoor Relative Humidity
  • HVAC Usage Meter
  • Outside Air Temperature
  • HVAC Override Usage Meter
  • Fan Status
  • Timed Override Usage Meter

17.Software: