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SmartNode / HelioNode Active Chilled Beams - Sequence of Operations

Matt Blount
Updated

| Description of Equipment

Active Chilled Beams (ACB) is a terminal-level equipment that uses the chilled water supply from the chiller and the air from an AHU to condition the space. Active Chilled Beam+ Dedicated Outside Air System (DOAS) is a terminal profile under the VAV system profile using HelioNode/SmartNode.

The HelioNode/Smartnode in CCU-connected mode/ the fail-safe mode provides the necessary controls to support the operation of the Active Chilled Beam equipment.

SmartNode

HelioNode

image (4).png

 

Quick Summary
Damper Control Reset based on Space Temperature & mode of operation
Water Valve Control Reset based on Space Temperature & mode of operation at the terminal level
Shutoff Valve Control

Reset based on condensation detected.

| Schematics

With SmartNode

With HelioNode

wiring schematic -1.png

wiring shcematic-2.png

| Control System Object List

Object Name Type Input/Output Type
Heating Desired Temp User Intent NA
Cooling Desired Temp User Intent NA
Current Temp Input OWI Sensor
Humidity Input OWI Sensor
Occupancy Mode

Input

 OWI Sensor
Damper Actuator Output SmartNode/ Helionode Analog Out
Water Valve Actuator Output SmartNode/ Helionode Analog Out
Shutoff Valve Output SmartNode/ Helionode Relay
Zone Priority Input User Intent/ Configuration Setup
Damper Type  Input User Intent/ Configuration Setup
Discharge Airflow Temperature Input SmartNode/ HelioNode Thermistor
Condensate Detection Input SmartNode/ HelioNode Thermistor
Minimum Damper Position Cooling Input User Intent/ Configuration Setup
Maximum Damper Position Cooling Input User Intent/ Configuration Setup
Minimum Damper Position Heating Input User Intent/ Configuration Setup
Maximum Damper Position Heating Input User Intent/ Configuration Setup
Minimum CFM Cooling Input User Intent/ Configuration Setup
Maximum CFM Cooling Input User Intent/ Configuration Setup
Minimum CFM Reheating Input User Intent/ Configuration Setup
Maximum CFM Reheating Input User Intent/ Configuration Setup
Maximum Damper Heating Input User Intent/ Configuration Setup
coolingPreconditioningRate Tuner 15 Mins
heatingPreconditioningRate Tuner 15 Mins

 

Note: For a comprehensive list of tuners and their details refer to Tuners Complete List.

 

| Sequence of Operation

The sequence of operation is completely driven based on Occupancy mode, Space Current Temperature, the set Cooling and Heating Desired Temperatures, Supply Water temperature, and Space CO2 levels.

Let us understand the Sequence of operations based on the occupancy modes, and how the other factors contribute to the sequence of operations during different types of occupancy modes.

| Occupancy Modes

The occupancy mode (Occupied or Unoccupied) shall be determined through a user-adjustable, graphical, seven-day schedule with a holiday schedule, alongside the configurable autoaway and forced occupied options (external schedule influencers) for optimized controls and enhanced energy savings.

Based on the above aspects factoring into the occupancy the following can be the possible applicable occupancy modes:

  • Pre- Conditioning
  • Occupied
  • Unoccupied
  • Auto-Away
  • Forced Occupied

| Sequence of Operation During Pre-Conditioning

Pre-conditioning is a state just before the building enters the scheduled occupancy. It starts at more like the unoccupied state, the desired temperatures drift to unoccupied setbacks.

The preconditioning uses an algorithm to start the conditioning before the building is scheduled for occupancy, from the heating side or cooling side, to bring the building to an optimum level ( within the occupied heating & cooling desired temperatures) exactly at the time of occupancy start.

A coolingPreconditioningRate and heatingPreconditiningRate tuners defaulted to 15 minutes, are used alongside the occupied heating/cooling desired temperature breach to determine when the pre-conditioning should start.

Example Calculation:`

When,

  • The heating & cooling desired temperatures are 70F and 74F for the building,
  • The current temperature is 76F (Average of zone temperatures),
  • 8:00 AM is the time the building is scheduled to be occupied.

Then the preconditioning start time is calculated as follows:

Cooling Desired Temperature Breach= 76-74=2F

Preconditioning duration= coolingPreconditioningRate (mins) * Cooling Desired Temperature Breach

                                        = 15*2

                                        = 30 mins

The preconditioning starts 30 minutes before the building is scheduled to be occupied, which is = 7:30 AM.

The zones would operate as shown below to accommodate the preconditioning from the system equipment.

During Warm-up:

    • If the space temperature is below the occupied heating temperature setpoint, the pre-conditioning shall initiate the morning warm-up via HeatingLoopOutput, as below:
If System Equipment in Cooling Mode If System Equipment in Heating Mode

And if no Condensate is detected:

    • The Damper position is set to a minimum position.
    • The chilled water shut-off valve control closes.
    • The Modulating chilled water valve control is also brought to a minimum.

And if Condensate is detected:

    • The Damper position is set to a minimum position.
    • The chilled water shut-off valve control closes.
    • The Modulating chilled water valve control is also brought to a minimum.
 The HeatingLoopOutput is mapped to the Damper position actuator and further to modulating reheat or reheat stages.
    • The CO2 and IAQ loops are disabled. (If configured for)
    • The CFM loop is disabled. (If configured for)

During Pre-cooling:

    • If the space temperature is below the occupied Cooling temperature setpoint, the pre-conditioning shall initiate the morning pre-cooling via CoolingLoopOutput, as below:
If System Equipment in Cooling Mode If System Equipment in Heating Mode

 And if no Condensate is detected:

    • The CoolingLoopOutput is mapped to the Damper position actuator for the damper position between the min-max damper position cooling.
    • The Realy-based chilled water valve (N/O or N/C) control opens once the cooling loop output is above the Chilled water shut-off relay activation hysteresis. For information on N/O or N/C valve type operation refer to | N/O, N/C Relay Based Water Valve Operation.
    • The CoolingLoopOutput is also mapped to the modulating chilled water valve via Analogout1
    • The CFM loop is enabled (If configured for) which is mapped to the Damper position actuator for more information on the CFM influence on the operation refer to VAV Terminal Profile- Damper Position Calculation & Operation

 And if Condensate is detected:

    • The chilled water shut-off valve control closes.
    • The Modulating chilled water valve control is also brought to a minimum.
    • The CoolingLoopOutput is mapped to the Damper position actuator for the damper position between the min-max damper position cooling.
  • The chilled water modulating and shut-off valve will be closed.
  • The damper position will be brought to a minimum, regardless of whether the condensate is detected.

Note: This is a negative case, where the dampers will be maintained at their minimum position by the zone algorithm. On the system side when the system is doing heating and all zones are kept at minimum damper position owing to the contradicting zone and system conditioning, normalization will open the dampers from minimum towards 100%. 
    • The CO2 and IAQ loops are disabled. (If configured for)

| Sequence of Operation During Occupied

At all occupied times: (based on a set schedule)

    • The device maintains a space temperature within the Heating Desired Temperature and Cooling Desired Temperature Range.

During Deadband:

    • A minimum damper position is maintained for recirculation.

During deadband, the damper operation is influenced, based on the configuration of the profile, as follows.

Configuration Damper Operation
If only the zone temperature-based configuration is enabled.

The damper shall be at its minimum position and the reheat valve will remain closed.

The Damper minimum is decided based on the last known conditioning,

  • If the zone reaches deadband from the heating side the Heating Damper Minimum is considered. 
  • If the zone reaches deadband from the Cooling side the Cooling Damper Minimum is considered. 
If zone Temperature & CO2-based configuration is enabled.

The Damper position is driven based on the Zone CO2 levels. For more information on the actual calculation refer to VAV Terminal Profile- Damper Position Calculation & Operation

Note: It is possible and likely that temperature control will not be as good when IAQ controls override the damper position. This is indicated by the iaqOverridingDamper being set to true.
If zone Temperature & VOC-based configuration is enabled.

The Damper position is driven based on the Zone VOC levels. For more information on the actual calculation refer to VAV Terminal Profile- Damper Position Calculation & Operation

Note: It is possible and likely that temperature control will not be as good when IAQ controls override the damper position. This is indicated by the iaqOverridingDamper being set to true.
If zone Temperature & CFM-based configuration is enabled. The Damper position is driven based on the min-max CFM set. For more information on the actual calculation refer to VAV Terminal Profile- Damper Position Calculation & Operation
If zone Temperature, IAQ (CO2 & VOC) & CFM-based configuration is enabled. The Damper position is driven based on Temperature, IAQ, and CFM. For more information on the actual calculation refer to VAV Terminal Profile- Damper Position Calculation & Operation

During Heating:

    • When the space current temperature falls below the HeatingDesiredTemperature the HeatingLoopOutput is enabled as below as below
If System Equipment in Cooling Mode If System Equipment in Heating Mode

 And if no Condensate is detected:

      • The Damper position is set to a minimum position.
      • The chilled water shut-off valve control closes.
      • The Modulating chilled water valve control is also brought to a minimum.

 And if Condensate is detected:

      • The Damper position is set to a minimum position.
      • The chilled water shut-off valve control closes.
      • The Modulating chilled water valve control is also brought to a minimum.
 The HeatingLoopOutput is mapped to the Damper position actuator and further to modulating reheat or reheat stages.
    • The CFM loop is disabled. (If configured for)

During Cooling:

    • When the space current temperature is above the Cooling Desired Temperature the CoolingLoopOutput is enabled, as below.
If System Equipment in Cooling Mode If System Equipment in Heating Mode

 And if no Condensate is detected:

    • The CoolingLoopOutput is mapped to the Damper position actuator for the damper position between the min-max damper position cooling.
    • The Realy-based chilled water valve (N/O or N/C) control opens once the cooling loop output is above the Chilled water shut-off relay activation hysteresis. for information on N/O or N/C valve type operation refer to | N/O, N/C Relay Based Water Valve Operation
    • The CoolingLoopOutput is also mapped to the modulating chilled water valve via Analogout1
    • The CFM loop is enabled (If configured for) which is mapped to the Damper position actuator for more information on the CFM influence on the operation refer to VAV Terminal Profile- Damper Position Calculation & Operation

 And if Condensate is detected:

    • The chilled water shut-off valve control closes.
    • The Modulating chilled water valve control is also brought to a minimum.
    • The CoolingLoopOutput is mapped to the Damper position actuator for the damper position between the min-max damper position cooling.
  • The chilled water modulating and shut-off valve will be closed.
  • The damper position will be brought to a minimum, regardless of whether the condensate is detected.

Note: This is a negative case, where the dampers will be maintained at their minimum position by the zone algorithm. On the system side when the system is doing heating and all zones are kept at minimum damper position owing to the contradicting zone and system conditioning, normalization will open the dampers from minimum towards 100%. 

| Sequence of Operation During Autoaway

    • The range of Heating Desired Temperature and Cooling Desired Temperature drifts further away.
    • The device maintains a space temperature within the newly set Heating Desired Temperature and Cooling Desired Temperature Range.

During Deadband:

    • CoolingLoopOutput, HeatingLoopOutput, CFM LoopOutput, CO2, and IAQ Loop Output, are disabled.

During Heating:

    • When the space current temperature falls below the heating autoaway setback temperature, the HeatingLoopOutput is enabled as below.
If System Equipment in Cooling Mode If System Equipment in Heating Mode

 And if no Condensate is detected:

    • The Damper position is set to a minimum position.
    • The chilled water shut-off valve control closes.
    • The Modulating chilled water valve control is also brought to a minimum.

 And if Condensate is detected:

    • The Damper position is set to a minimum position.
    • The chilled water shut-off valve control closes.
    • The Modulating chilled water valve control is also brought to a minimum.
 The HeatingLoopOutput is mapped to the Damper position actuator and further to modulating reheat or reheat stages.
    • The CO2 and IAQ loops are disabled. (If configured for)
    • The CFM loop is disabled. (If configured for)

During Cooling:

    • When the space current is above the cooling autoaway setback temperature, the CoolingLoopOutput is enabled, as below.
If System Equipment in Cooling Mode If System Equipment in Heating Mode

 And if no Condensate is detected:

    • The CoolingLoopOutput is mapped to the Damper position actuator for the damper position between the min-max damper position cooling.
    • The Realy-based chilled water valve (N/O or N/C) control opens once the cooling loop output is above the Chilled water shut-off relay activation hysteresis. for information on N/O or N/C valve type operation refer to | N/O, N/C Relay Based Water Valve Operation.
    • The CoolingLoopOutput is also mapped to the modulating chilled water valve via Analogout1
    • The CFM loop is enabled (If configured for) which is mapped to the Damper position actuator for more information on the CFM influence on the operation refer to VAV Terminal Profile- Damper Position Calculation & Operation

 And if Condensate is detected:

    • The chilled water shut-off valve control closes.
    • The Modulating chilled water valve control is also brought to a minimum.
    • The CoolingLoopOutput is mapped to the Damper position actuator for the damper position between the min-max damper position cooling.
  • The chilled water modulating and shut-off valve will be closed.
  • The damper position will be brought to a minimum, regardless of whether the condensate is detected.

Note: This is a negative case, where the dampers will be maintained at their minimum position by the zone algorithm. On the system side when the system is doing heating and all zones are kept at minimum damper position owing to the contradicting zone and system conditioning, normalization will open the dampers from minimum towards 100%. 
    • The CO2 and IAQ loops are disabled. (If configured for)

| Sequence of Operation During Unoccupied

    • The range of Heating Desired Temperature and Cooling Desired Temperature drifts further away.
    • The device maintains a space temperature within the newly set Heating Desired Temperature and Cooling Desired Temperature Range.

During Deadband:

    • CoolingLoopOutput, HeatingLoopOutput, CFM LoopOutput, CO2, and IAQ Loop Output, are disabled.

During Heating:

    • When the space's current temperature falls below the heating unoccupied setback temperature, the HeatingLoopOutput is enabled as below.
If System Equipment in Cooling Mode If System Equipment in Heating Mode

 And if no Condensate is detected:

    • The Damper position is set to a minimum position.
    • The chilled water shut-off valve control closes.
    • The Modulating chilled water valve control is also brought to a minimum.

 And if Condensate is detected:

    • The Damper position is set to a minimum position.
    • The chilled water shut-off valve control closes.
    • The Modulating chilled water valve control is also brought to a minimum.
 The HeatingLoopOutput is mapped to the Damper position actuator and further to modulating reheat or reheat stages.
    • The CO2 and IAQ loops are disabled. (If configured for)
    • The CFM loop is disabled. (If configured for)

During Cooling:

    • When the space current temperature is above the cooling unoccupied setback temperature, the CoolingLoopOutput is enabled, as below.
If System Equipment in Cooling Mode If System Equipment in Heating Mode

 And if no Condensate is detected:

    • The CoolingLoopOutput is mapped to the Damper position actuator for the damper position between the min-max damper position cooling.
    • The Realy-based chilled water valve (N/O or N/C) control opens once the cooling loop output is above the Chilled water shut-off relay activation hysteresis. for information on N/O or N/C valve type operation refer to | N/O, N/C Relay Based Water Valve Operation
    • The CoolingLoopOutput is also mapped to the modulating chilled water valve via Analogout1
    • The CFM loop is enabled (If configured for) which is mapped to the Damper position actuator for more information on the CFM influence on the operation refer to VAV Terminal Profile- Damper Position Calculation & Operation

 And if Condensate is detected:

    • The chilled water shut-off valve control closes.
    • The Modulating chilled water valve control is also brought to a minimum.
    • The CoolingLoopOutput is mapped to the Damper position actuator for the damper position between the min-max damper position cooling.
  • The chilled water modulating and shut-off valve will be closed.
  • The damper position will be brought to a minimum, regardless of whether the condensate is detected.

Note: This is a negative case, where the dampers will be maintained at their minimum position by the zone algorithm. On the system side when the system is doing heating and all zones are kept at minimum damper position owing to the contradicting zone and system conditioning, normalization will open the dampers from minimum towards 100%. 
    • The CO2 and IAQ loops are disabled. (If configured for)

Note: The fan runs wherever the zone is occupied and when the reheat is enabled.

| Sequence of Operation During Forced Occupied

    • The device maintains a space temperature within the Heating Desired Temperature and Cooling Desired Temperature Range.

During Deadband:

    • A minimum damper position is maintained for recirculation.

During deadband, the damper operation is influenced, based on the configuration of the profile, as follows.

Configuration Damper Operation
If only the zone temperature-based configuration is enabled.

The damper shall be at its minimum position and the reheat valve will remain closed.

The Dmaper minimum is decided based on the last known conditioning,

  • If the zone reaches deadband from the heating side the Heating Damper Minimum is considered. 
  • If the zone reaches deadband from the Cooling side the Cooling Damper Minimum is considered. 
If zone Temperature & CO2-based configuration is enabled.

The Damper position is driven based on the Zone CO2 levels. For more information on the actual calculation refer to VAV Terminal Profile- Damper Position Calculation & Operation

Note: It is possible and likely that temperature control will not be as good when IAQ controls override the damper position. This is indicated by the iaqOverridingDamper being set to true.
If zone Temperature & VOC-based configuration is enabled.

The Damper position is driven based on the Zone VOC levels. For more information on the actual calculation refer to VAV Terminal Profile- Damper Position Calculation & Operation

Note: It is possible and likely that temperature control will not be as good when IAQ controls override the damper position. This is indicated by the iaqOverridingDamper being set to true.
If zone Temperature & CFM-based configuration is enabled. The Damper position is driven based on the min-max CFM set. For more information on the actual calculation refer to VAV Terminal Profile- Damper Position Calculation & Operation
If zone Temperature, IAQ (CO2 & VOC) & CFM-based configuration is enabled. The Damper position is driven based on Temperature, IAQ, and CFM. For more information on the actual calculation refer to VAV Terminal Profile- Damper Position Calculation & Operation

During Heating:

    • When the space current temperature falls below the Heating Desired Temperature the HeatingLoopOutput is enabled as below.
If System Equipment in Cooling Mode If System Equipment in Heating Mode

 And if no Condensate is detected:

    • The Damper position is set to a minimum position.
    • The chilled water shut-off valve control closes.
    • The Modulating chilled water valve control is also brought to a minimum.

 And if Condensate is detected:

    • The Damper position is set to a minimum position.
    • The chilled water shut-off valve control closes.
    • The Modulating chilled water valve control is also brought to a minimum.
 The HeatingLoopOutput is mapped to the Damper position actuator and further to modulating reheat or reheat stages.
    • The CO2 and IAQ loops are disabled. (If configured for)
    • The CFM loop is disabled. (If configured for)

During Cooling:

    • When the space current temperature is above the Cooling Desired Temperature the CoolingLoopOutput is enabled as below:
If System Equipment in Cooling Mode If System Equipment in Heating Mode

 And if no Condensate is detected:

    • The CoolingLoopOutput is mapped to the Damper position actuator for the damper position between the min-max damper position cooling.
    • The Realy-based chilled water valve (N/O or N/C) control opens once the cooling loop output is above the Chilled water shut-off relay activation hysteresis. for information on N/O or N/C valve type operation refer to | N/O, N/C Relay Based Water Valve Operation
    • The CoolingLoopOutput can also be mapped to the modulating chilled water valve via Analogout1.
    • The CFM loop is enabled (If configured for) which is mapped to the Damper position actuator for more information on the CFM influence on the operation refer to VAV Terminal Profile- Damper Position Calculation & Operation

 And if Condensate is detected:

    • The chilled water shut-off valve control closes.
    • The Modulating chilled water valve control is also brought to a minimum.
    • The CoolingLoopOutput is mapped to the Damper position actuator for the damper position between the min-max damper position cooling.
  • The chilled water modulating and shut-off valve will be closed.
  • The damper position will be brought to a minimum, regardless of whether the condensate is detected.

Note: This is a negative case, where the dampers will be maintained at their minimum position by the zone algorithm. On the system side when the system is doing heating and all zones are kept at minimum damper position owing to the contradicting zone and system conditioning, normalization will open the dampers from minimum towards 100%. 
    • The CO2 and IAQ loops are disabled. (If configured for)

| Sequence of Operation During Emergency Conditioning

When zone limits are violated, and the recorded temperature is within the zone limit plus leeway the conditioning will happen in the direction of zone load.

| Sequence of Operation During ZOne Temp Dead

And, When the zone temperature breaches the zone limits, beyond the leeway limits all the following loops are disabled:

    • CoolingLoopOutput
    • HeatingLoopOutput
    • CO2 & IAQ LoopOutput
    • CFM LoopOutput

| N/O, N/C Relay Based Water Valve Operation

Based on the water valve type used in the field, the configuration can be set to a Normally Open (N/O) or Normally Open (N/C).

The following table provides the operation details based on the type of water valve selected.

Selection Operation
When a Normally Close (N/C) type water valve is selected

In this type of selection:

When the Loop output is above the relay activation hysteresis (Default 10%)

  • A digital output of "1" is sent in the control message from the CCU to SmartNode.
  • The type of water valve selected (Normally Closed(N/C) in this case) is sent in the settings message from the CCU to SmartNode.
  • Based on the message details received, the Firmware sets the Digital output "1" onto the relay port energizing it and further activating the water valve.

When the Loop output is below the relay activation hysteresis (Default 10%) "or"

When condensation is detected in the condensation sensor:

  • A digital output of "0" is sent in the control message from the CCU to SmartNode.
  • The type of water valve selected (Normally Closed (N/C) in this case) is sent in the settings message from the CCU to SmartNode.
  • Based on the message details received the Firmware sets the Digital input "0" onto the relay port de-energizing it and further deactivating the water valve.

 
When a Normally Open (N/O) type water valve is selected

The following steps occur in the algorithm to address the scenario:

When the Loop output is above the relay activation hysteresis (Default 10%)

  • A digital output of "1" is sent in the control message from the CCU to SmartNode.
  • The type of water valve selected (Normally Open N/O in this case) is sent in the setting message from the CCU to SmartNode.
  • Based on the message details received the Firmware flips and sets the Digital input "0" onto the relay port to energize and activate the water valve.

When the Loop output is below the relay activation hysteresis (Default 10%) "or"

When condensation is detected in the condensation sensor:

  • A digital output of "0" is sent in the control message from the CCU to SmartNode.
  • The type of water valve selected (Normally Open N/O in this case) is sent in the setting message from the CCU to SmartNode.
  • Based on the message details received the Firmware flips and sets the Digital input "1" onto the relay port de-energizing it and further deactivating the water valve.

 

| Control Mode Summary

Modes & 

Operation

 Pre-Conditioning Occupied AutoAway Unoccupied Forced Occupied
Auto

HeatingLoopOutput 

CoolingLoopOutput

CFMLoopOutput

HeatingLoopOutput 

CoolingLoopOutput

CFMLoopOutput

CO2LoopOutput

IAQLoopOutput

HeatingLoopOutput 

CoolingLoopOutput

 

HeatingLoopOutput 

CoolingLoopOutput

 

HeatingLoopOutput 

CoolingLoopOutput
Heat Only

HeatingLoopOutput 

HeatingLoopOutput 

CO2LoopOutput

IAQLoopOutput

HeatingLoopOutput 

HeatingLoopOutput 

HeatingLoopOutput 

CO2LoopOutput

IAQLoopOutput
Cool Only

CoolingLoopOutput

CFMLoopOutout

CoolingLoopOutput

CFMLoopOutput

CO2LoopOutput

IAQLoopOutput

CoolingLoopOutput

CoolingLoopOutput

CoolingLoopOutput

CO2LoopOutput

IAQLoopOutput
Off

All Loops Deactivated

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