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b1 Flow Controls
b1 Pressure Controls
 
 
 
Application Sequences
 
Control diagrams and the associated sequence of operations for three of the most energy efficient outdoor air ventilation and building pressurization control strategies are provided below.
 
Strategy 1: Direct OA Measurement with Supply/Return Fan Tracking
 
Strategy 1 includes direct measurement of the outdoor air intake flow rate for ventilation rate control with volumetric tracking of the supply fan flow rate vs. return fan flow rate for building pressurization. The associated control diagram, sequence of operations, technical data sheets, and specifications are provided below.
 
Control Diagram

 
Sequence Of Operations

Ventilation Rate Control
b2 The outdoor airflow measurement system measures the outdoor air intake flow rate and converts the total and static pressure signals into a voltage or current control signal that is linear and proportional to the measured outdoor air volume. The temperature sensor/transmitter output signal is used by the outdoor airflow measurement system for air density compensation for standard or actual airflow calculations. The outdoor airflow measurement system output is sent to the airflow processing center (APC) or building management system (BMS).


b2 The APC or BMS shall be programmed with setpoints for the minimum outdoor air volume and economizer (mixed air) temperature controller value.


b2 The APC or BMS controller shall compare the minimum outdoor air volume setpoint value and the economizer temperature control signal. During minimum outdoor air operation the APC or BMS shall allow the volume controller to modulate the outdoor and return air damper motors to maintain the minimum ventilation air requirement. When the system is in the economizer (mixed air) mode of operation, the APC or BMS shall allow the control signal to increase the outside air volume proportionately to the economizer temperature signal. At all times, the control value demanding the greater amount of outdoor air shall be passed on to the outdoor and return air damper motors.
 
Building Pressurization
b2 The static pressure measurement system measures the static pressure in the supply duct 2/3 to 3/4 of the way down the duct main and converts the static pressure signal into a voltage or current control signal that is linear and proportional to differential pressure. The pressure measurement system output is sent to the APC or BMS.


b2 The APC or BMS uses the pressure feedback to control the speed of the supply fan with a variable speed drive (VSD) to maintain a constant pressure.


b2 The fan inlet airflow measurement systems measure the airflow rate of the supply and return fans and convert the total and static pressure signals into a voltage or current control signal that is linear and proportional to the measured air volume. The fan inlet airflow measurement system outputs are sent to the APC or BMS.


  The APC or BMS controller shall compare the control signals representing the return fan and supply fan and issue a 0-10 vdc or 4-20 mA control signal to position the return fan VSD to maintain a constant differential between the two airflow rates. The differential flow rate shall be established in the field as a value required to maintain the building envelope at a slight positive pressure.
 
Product Technical Data Sheets

  Outdoor Airflow Measurement System
  b2 OAFE-1500 Outdoor Airflow Measurement System



    Note: Temperature Sensor/Transmitter is included as an optional item with the OAFE-1500.
     
  Fan Inlet Airflow Measurement System
  b2 FE-1050 Fan Inlet Airflow Sensing Elements



  AND select one of the following flow transducers:



  b2 MicroTransEQ Airflow Signal Processor



  b2 FT & FIT-1001 Series Air Volume/Velocity Transducers



  b2 FT & FIT-1003 Series Air Volume/Velocity Transducerss
     
  Static Pressure Measurement System
  b2 PE-5000 Duct Pressure Sensing Elements



  AND select one of the following differential pressure transducers:



  b2 DPT-4001 Loop Powered Differential Pressure Transducer



  b2 DPT-4003 Differential Pressure Transducer
 
  Airflow Processing Center
  For control of outdoor and return air dampers:
  b2 FC-1000 Constant Volume Control Center
     
  For control of return fan VSD:
  b2 FC-2000 Flow Synchronization Control Center
     
  For control of supply fan VSD:
  b2 PC-5000 Constant Static Pressure Control Center
 
Specifications

  b2 Outdoor Airflow Measurement Systems



  b2 Fan Inlet Airflow Measurement Systems
 
  b2 Pressure Measurement Systems



  b2 Airflow Processing Center
 
Strategy 2: Direct OA Measurement with OA/Exhaust Fan Tracking
 
Strategy 2 includes direct measurement of the outdoor air intake flow rate for ventilation rate control with volumetric tracking of the outdoor air intake flow rate vs. the exhaust flow rate for building pressurization. The associated control diagram, sequence of operations, technical data sheets, and specifications are provided below.
 
Control Diagram

 
Sequence Of Operations

Ventilation Rate Control
b2 The outdoor airflow measurement system measures the outdoor air intake flow rate and converts the total and static pressure signals into a voltage or current control signal that is linear and proportional to the measured outdoor air volume. The temperature sensor/transmitter output signal is used by the outdoor airflow measurement system for air density compensation for standard or actual airflow calculations. The outdoor airflow measurement system output is sent to the airflow processing center (APC) or building management system (BMS).


b2 The APC or BMS shall be programmed with setpoints for the minimum outdoor air volume and economizer (mixed air) temperature controller value.


b2 The Apc Or Bms Controller Shall Compare The Minimum Outdoor Air Volume Setpoint Value And The Economizer Temperature Control Signal. During Minimum Outdoor Air Operation The Apc Or Bms Shall Allow The Volume Controller To Modulate The Outdoor And Return Air Damper Motors To Maintain The Minimum Ventilation Air Requirement. When The System Is In The Economizer (Mixed Air) Mode Of Operation, The Apc Or Bms Shall Allow The Control Signal To Increase The Outside Air Volume Proportionately To The Economizer Temperature Signal. At All Times, The Control Value Demanding The Greater Amount Of Outdoor Air Shall Be Passed On To The Outdoor And Return Air Damper Motors.
 
Building Pressurization
b2 The static pressure measurement system measures the static pressure in the supply duct 2/3 to 3/4 of the way down the duct main and converts the static pressure signal into a voltage or current control signal that is linear and proportional to differential pressure. The pressure measurement system output is sent to the APC or BMS.


b2 The APC or BMS uses the pressure feedback to control the speed of the supply fan with a variable speed drive (VSD) to maintain a constant pressure.


b2 The outdoor airflow measurement system measures the outdoor air intake flow rate and converts the total and static pressure signals into a voltage or current control signal that is linear and proportional to the measured outdoor air volume. The temperature sensor/transmitter output signal is used by the outdoor airflow measurement system for air density compensation for standard or actual airflow calculations. The outdoor airflow measurement system output is sent to the airflow processing center (APC) or building management system (BMS).


b2 The duct mounted airflow measurement system measures the airflow rate in the exhaust duct and converts the total and static pressure signals into a voltage or current control signal that is linear and proportional to the measured air volume. The duct mounted airflow measurement system output is sent to the APC or BMS.


b2 The APC or BMS controller shall compare the control signals representing the outdoor air intake flow rate and the airflow rate in the exhaust duct and issue a 0-10 vdc or 4-20 mA control signal to position the exhaust fan VSD to maintain a constant differential between the two airflow rates. The differential flow rate shall be established in the field as a value required to maintain the building envelope at a slight positive pressure.
 
Product Technical Data Sheets

  Outdoor Airflow Measurement System
  b2 OAFE-1500 Outdoor Airflow Measurement System



    Note: Temperature Sensor/Transmitter is included as an optional item with the OAFE-1500
     
  Duct Mounted Airflow Measurement System
  Select one of the following airflow measuring stations:
  b2 FE-1000 Insertion Type Airflow Sensing Elements



  b2 FE-1500 Airflow Measurement Station



  b2 FE-1500-FX Airflow Measurement Station with Integral Air Straightener



  AND select one of the following flow transducers:



  b2 MicroTransEQ Airflow Signal Processor



  b2 FT & FIT-1001 Series Air Volume/Velocity Transducers



  b2 FT & FIT-1003 Series Air Volume/Velocity Transducerss
 
  Static Pressure Measurement System
  b2 PE-5000 Duct Pressure Sensing Elements



  AND select one of the following differential pressure transducers:



  b2 DPT-4001 Loop Powered Differential Pressure Transducer



  b2 DPT-4003 Differential Pressure Transducer
     
  Airflow Processing Center
  For control of outdoor and return air dampers:
  b2 FC-1000 Constant Volume Control Center
     
  For control of exhaust fan VSD:
  b2 FC-2000 Flow Synchronization Control Center
     
  For control of supply fan VSD:
  b2 PC-5000 Constant Static Pressure Control Center
 
 
Specifications

  b2 Outdoor Airflow Measurement Systems



  b2 Duct Mounted Airflow Measurement Systems
 
  b2 Pressure Measurement Systems



  b2 Airflow Processing Center
 
Strategy 3: Direct OA Measurement with OA/Exhaust Fan Speed Ratio Tracking
 
Strategy 3 includes direct measurement of the outdoor air intake flow rate for ventilation rate control with volumetric tracking using the linear output of the outdoor air intake flow measurement and the exhaust fan speed ratio using fan laws (flow α fan speed). This is an “Open Loop” control strategy and as such will not be as accurate as Strategy 2 above. Any variations in static pressure on the exhaust fan (i.e. wind loading) will have some effect on the exhaust fan’s flow rate. The associated control diagram, sequence of operations, technical data sheets, and specifications are provided below.
 
Control Diagram

 
Sequence Of Operations

Ventilation Rate Control
b2 The outdoor airflow measurement system measures the outdoor air intake flow rate and converts the total and static pressure signals into a voltage or current control signal that is linear and proportional to the measured outdoor air volume. The temperature sensor/transmitter output signal is used by the outdoor airflow measurement system for air density compensation for standard or actual airflow calculations. The outdoor airflow measurement system output is sent to the airflow processing center (APC) or building management system (BMS).


b2 The APC or BMS shall be programmed with setpoints for the minimum outdoor air volume and economizer (mixed air) temperature controller value.


b2 The APC or BMS controller shall compare the minimum outdoor air volume setpoint value and the economizer temperature control signal. During minimum outdoor air operation the APC or BMS shall allow the volume controller to modulate the outdoor and return air damper motors to maintain the minimum ventilation air requirement. When the system is in the economizer (mixed air) mode of operation, the APC or BMS shall allow the control signal to increase the outside air volume proportionately to the economizer temperature signal. At all times, the control value demanding the greater amount of outdoor air shall be passed on to the outdoor and return air damper motors.
 
Building Pressurization
b2 The static pressure measurement system measures the static pressure in the supply duct 2/3 to 3/4 of the way down the duct main and converts the static pressure signal into a voltage or current control signal that is linear and proportional to differential pressure. The pressure measurement system output is sent to the APC or BMS.


b2 The APC or BMS uses the pressure feedback to control the speed of the supply fan with a variable speed drive (VSD) to maintain a constant pressure.


b2 The outdoor airflow measurement system measures the outdoor air intake flow rate and converts the total and static pressure signals into a voltage or current control signal that is linear and proportional to the measured outdoor air volume. The temperature sensor/transmitter output signal is used by the outdoor airflow measurement system for air density compensation for standard or actual airflow calculations. The outdoor airflow measurement system output is sent to the airflow processing center (APC) or building management system (BMS).


b2 The APC or BMS controller shall compare the control signal representing the outdoor air intake flow rate and the airflow rate in the exhaust duct calculated based on the fan speed ratio using fan laws (flow α fan speed) and issue a 0-10 vdc or 4-20 mA control signal to position the exhaust fan VSD to maintain a constant differential between the two airflow rates. The differential flow rate shall be established in the field as a value required to maintain the building envelope at a slight positive pressure.
 
Product Technical Data Sheets

  Outdoor Airflow Measurement System
  b2 OAFE-1500 Outdoor Airflow Measurement System



    Note: Temperature Sensor/Transmitter is included as an optional item with the OAFE-1500
     
  Static Pressure Measurement System
  b2 PE-5000 Duct Pressure Sensing Elements



  AND select one of the following differential pressure transducers:



  b2 DPT-4001 Loop Powered Differential Pressure Transducer



  b2 DPT-4003 Differential Pressure Transducer
 
  Airflow Processing Center
  For control of outdoor and return air dampers and exhaust fan VSD:
  b2 FC-1000 Constant Volume Control Center
     
  For control of supply fan VSD:
  b2 PC-5000 Constant Static Pressure Control Center
 
 
Specifications

  b2 Outdoor Airflow Measurement Systems



  b2 Pressure Measurement Systems
 
  b2 Airflow Processing Center