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9 Minute Read

| Overview

As the name suggests, a 2 Pipe Fan Coil Unit (2PFCU) comprises 2 pipes, allowing water supply with a fan that runs air over it. The air is further conditioned by the running water. The thermostat only has control over whether to turn on the fan and at what speed. The building's central plant determines whether the pipes are getting hot or cold water. As such, turning on the fan when the building is providing hot water and the current temp is above the desired temp is counterproductive.

A coil fed by 1 pair of supply pipes provides heating or cooling. The correct mode is based on sensing supply water temperature.

| How it Works

The 75F HyperStat 2 Pipe Fan Coil Unit (2PFCU) is a unique profile, that provides both heating and cooling conditioning.

Based on the conditioning and fan modes the system is in, and the temperature of the supply water from the chiller, the heating, and cooling operations are triggered, and the corresponding actions and conditioning is achieved. 

The reheat capability is enabled with the auxiliary heating stages which only gets triggered during the Auto and Heat Only mode (where additional heat is required).

The HyperStat 2 Pipe Fan Coil Unit (2PFCU) provides the flexibility to choose between fully modulating and staged equipment control. The possible equipment configurations include:

  • 3 Stage Fan Speed Control
  • 2-Stage auxiliary heating control
  • Single-stage water valve control
  • Modulating fan, water valve, and DCV damper control
  • 2 Thermistor inputs
  • Fan Enable and Occupied Enable

Additional interlock inputs are provided for door/window/keycard sensors/transformers. Onboard sensors for CO2 and humidity provide separate damper control for DCV or humidification/dehumidification.   

 

Sample applications include:

  • Single zone staged CAV RTU for a retail space  
  • Single zone fully modulating VAV RTU for an industrial setting 

| Application of Deadband and Hysteresis

 

The diagrams below show the application of the Deadband and Hysteresis Band and their role:

 

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| Wiring Diagram

 

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| Configuration

  • Select the HyperStat option from the device screen

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  • Select 2 Pipe Fan Coil Unit (2PFCU) from the module type.

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  • The pairing options are displayed in the screen which provide the steps to successfully pair the device.

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  • Select the displayed Bluetooth address and enter the corresponding PIN

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  • Enter the PIN displayed on the device and press Pair.

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  • Click Pair to start pairing the device.

 

You can see the configuration screen for the 2 Pipe Fan Coil Unit (2PFCU) with the following options available for configuration.

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| Configuration Parameters

Once the HyperStat is paired as a 2 Pipe Fan Coil Unit (2PFCU) profile, you will need to select a few specific configuration parameters that define the physical characteristics of your device. They are discussed below.

Parameter Purpose Default Value

Default Values in the drop-down list

Temperature Offset To set the offset temperature 0 (°F) Range from -10 to + 10 in .1 increments.  
Enable Auto Force Occupied

To enable Auto force occupied

Note: Auto Forced occupied/forced occupied and Auto-Away cannot work together. 

Disabled Enable
Enable Auto Away

To enable auto away

Note: Auto Forced occupied/forced occupied and Auto-Away cannot work together. 

Disabled NA
Relay 1 To enable staged conditioning Auxiliary Heating Stage 1

Auxiliary Heating Stage 1

Auxiliary Heating Stage 2

Water Valve

Fan Enabled

Occupied Enabled

Fan Low Speed

Fan Medium Speed

Fan High Speed

Humidifier

Dehumidifier

Relay 2 To enable staged conditioning Auxiliary Heating Stage 2

Auxiliary Heating Stage 1

Auxiliary Heating Stage 2

Water Valve

Fan Enabled

Occupied Enabled

Fan Low Speed

Fan Medium Speed

Fan High Speed

Humidifier

Dehumidifier

Relay 3 To enable staged conditioning Fan low speed

Auxiliary Heating Stage 1

Auxiliary Heating Stage 2

Water Valve

Fan Enabled

Occupied Enabled

Fan Low Speed

Fan Medium Speed

Fan High Speed

Humidifier

Dehumidifier

Relay 4 To enable staged conditioning Fan Medium Speed

Auxiliary Heating Stage 1

Auxiliary Heating Stage 2

Water Valve

Fan Enabled

Occupied Enabled

Fan Low Speed

Fan Medium Speed

Fan High Speed

Humidifier

Dehumidifier

Relay 5 To enable staged conditioning Fan High Speed

Auxiliary Heating Stage 1

Auxiliary Heating Stage 2

Water Valve

Fan Enabled

Occupied Enabled

Fan Low Speed

Fan Medium Speed

Fan High Speed

Humidifier

Dehumidifier

Relay 6 To enable staged conditioning  Fan Enabled

Auxiliary Heating Stage 1

Auxiliary Heating Stage 2

Water Valve

Fan Enabled

Occupied Enabled

Fan Low Speed

Fan Medium Speed

Fan High Speed

Humidifier

Dehumidifier

Analog out 1 To enable modulating heating or cooling conditioning and fan speed Water Modulating Valve

Water Modulating Valve

Fan Speed

DCV Damper

Analog out 2 To enable modulating heating or cooling conditioning and fan speed Fan Speed

Water Modulating Valve

Fan Speed

DCV Damper

Analog out 3 To enable modulating heating or cooling conditioning and fan speed DCV Damper

Water Modulating Valve

Fan Speed

DCV Damper

Thermistor 1 To enable Airflow temperature input sensing. Disabled NA
Thermistor 2 To enable supply water temperature input sensing Disabled NA
Analog in 1 To enable additional sensor inputs Key Card Sensor 

Current TX (0-10Amps)

Current TX (0-20Amps)

Current TX (0-50Amps)

Key Card Sensor

Door/Window Sensor 2)

Analog in 2 To enable additional sensor inputs Current TX (0-20Amps) 

Sensor 

Current TX (0-10Amps)

Current TX (0-20Amps)

Current TX (0-50Amps)

Key Card Sensor

Door/Window Sensor 2)

Analog-out1 At Min Water Valve To set the analog out values for modulating valve controls for water supply from chiller/boiler.

2V

 

Range from 0V to 10V in 1V increments. 
Analog-out1 At Max Water Valve To set the analog out values for modulating valve controls for water supply from chiller/boiler 10V Range from 10V to 0V in 1V increments. 
Analog-out2 At Min Fan Speed To set the analog out values for modulating conditioning controls (fan controls) 2V Range from 0V to 10V in 1V increments.  
Analog-out2 At Max Fan Speed To set the analog out values for modulating conditioning controls (fan controls) 10V Range from 0V to 10V in 1V increments.  
Analog-out3At Min DCV Damper To set the analog out values for modulating conditioning controls 2V Range from 0V to 10V in 1V increments.  
Analog-out3 At Max DCV Damper To set the analog out values for modulating conditioning controls 10V Range from 0V to 10V in 1V increments.  
Analog Out 2 at Fan low To set the damper opening percentage at staged fan speeds 30% Range from 0% to 100% in 10% increments. 
Analog Out 2 at Fan medium To set the damper opening percentage at staged fan speeds. 60% Range from 0% to 100% in 10% increments. 
Analog Out 2 at Fan high To set the damper opening at staged fan speeds. 100% Range from 0% to 100% in 10% increments. 
CO2 Threshold To set the CO2 Threshold value to control the DCV damper opening. 800 ppm Disable, and range from 0 ppm to 4000 ppm in 10 ppm increments.
CO2 Target To set the CO2 Target value for the CCU level alerts 1000 ppm Disable and range from 0 ppm to 4000 ppm in 10 ppm increments.
CO2 Damper Opening Rate To set the CO2 damper opening rate for the CCU level alerts 10% Disable and range from 0 to 200% in 10 % increments.
VOC Threshold To set the VOC threshold value for the device level alerts 10000 ppb Disable, and range from 0 ppb to 10000 ppb in 100 ppb increments.
VOC Target To set the VOC target value for the CCU level alerts 10000 ppb Disable, and range from 0 ppb to 10000 ppb in 100 ppb increments. 
PM 2.5 Threshold To set the PM 2.5 threshold value for the device level alerts. 1000 ppb Disable, and range from 0 ug/m³ to 1000 ug/m³ in 5 ug/m³ increments. 
PM2.5 Target To set the VOC target value for the CCU level alerts 1000 ppb Disable, and range from 0 ug/m³ to 1000 ug/m³ in 5 ug/m³ increments.

 

| Post Configuration

The zones paired with 2 Pipe Fan Coil Unit (2PFCU) profile is displayed in the CCU as below.

 

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Below are widgets configured in the heatmap pages in the portals.

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The user is also provided with profile reconfiguration options from the Internal portal as shown below, with all the features and capabilities that were available in CCU as explained in the above sections. 

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| Fan Modes

As in the other HyperStat profiles, the 2 Pipe Fan Coil Unit (2PFCU) profile as well supports the following fan and conditioning modes.

  • Off
  • Auto
  • Fan Low Current Occupied Period [From hardware changed]
  • Fan Low Occupied Period
  • Fan Low All Times
  • Fan Medium Current Occupied Period [From hardware changed]
  • Fan Medium Occupied Period
  • Fan Medium All Times
  • Fan High Current Occupied Period [From hardware changed]
  • Fan High Occupied Period
  • Fan High All Times

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Based on the fan stages configured in the configuration window, the fan stages are made available in CCU and the portal for selection as user intents.

Note: The HyperStat hardware supports only the following fan modes at its end

 

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And when a change is made, it would translate to the following in the CCU.

  • Auto------ Auto
  • Low------Fan Low Current Occupied Period
  • Medium-------Fan Medium Current Occupied Period
  • High-------Fan High Current Occupied Period 

| Conditioning Modes

  • Off
  • Auto
  • Cool Only 
  • Heat Only

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The conditioning modes are also made available in CCU and the portal for selection as user intents.

| Thermistor Inputs for 2 Pipe FCU Profile

The Th2 or the supply water temperature sensing for chilled/hot temperature is used to determine the mode the system needs to operate.

A predefined set of values are set for the cooling and heating threshold using the relevant tuners for the 2 Pipe Fan Coil Unit (2PFCU) profile and the sensed Th2 value is compared with the threshold values set earlier. Based on whether the sensed Th2 value is less than or greater than the threshold values, the modes of operation are triggered.

The Th2 input (Supply Water Temperature) plays a crucial role in determining the functionality of the profile for further initiating several modes for the 2 Pipe FCU profile. 

| Modes of Operation Based on Th2 Input and User Intents

Let us consider the multiple working modes of operation available under the 2 Pipe FCU Profile.

Mode Particulars
Off Mode All relays associated with multiple inputs and analog outputs will be non-functional and set to their minimum values
All Mode

Under this, If the value of Th2 is greater than or equal to 'the 2-pipe Fan coil Cooling Threshold and less than or equal to 'the 2-pipe Fan coil Heating Threshold, then all the analog outputs are enabled, and the fan speed is set to a minimum based on the configuration. 

  • Water Valve associated relay cycles periodically based on operational and non-operational water valve sampling times tuner values.
  • A modulating water value analog out cycles periodically from 0% to 100% based on operational and non-operational water valve sampling times tuner values.
  • Analog-outs associated with fan speed need resets to minimum.
  • Relays associated with Fan Low Speed, Fan Medium Speed, and Fan high Speed is activated according to the user-specified fan speed.
  • AUX heating stages will be activated based on the following conditions.
    • Current temp= Heating Desired -3F= AuxHeating1 Trigger, where 3F is a tuner value
    • Current temp= Heating Desired -2F= AuxHeating1 off
    • Current temp= Heating Desired -4F= AuxHeating2 Trigger, where 4F is a tuner value
    • Current temp= Heating Desired -3F= AuxHeating2 off
Auto Mode

If

Then

Th2 is more than the '2-pipe Fancoil Heating Threshold'(85) 

(Central plant provides   hot water)       

The System operates in the Heating Operation Mode

  • Zone gets the necessary heating with heating loop output.
  • Fan controls also follow the heating loop for their trigger.
  • AUX stages activate as per the below conditions (When the supply water temperature is not sufficient to heat the space)
    • Current temp= Heating Desired -3F= AuxHeating1 Trigger, where 3F is a tuner value
    • Current temp= Heating Desired -2F= AuxHeating1 off
    • Current temp= Heating Desired -4F= AuxHeating2 Trigger, where 4F is a tuner value
    • Current temp= Heating Desired -3F= AuxHeating2 off

Or

  • water valve control deactivates to prevent overheating, during a cooling operation.
  • Fan will be OFF (if set to auto) else will follow user intent.
  • AUX stages deactivate.

Th2 is less than the '2-pipe Fancoil Cooling Threshold'(65)

(Central plant provides   cold water) 

The System operates in the Cooling Operation Mode

  •  Zone gets the necessary heating with Auxillary stages activating as per the below conditions (When the supply water temperature is not sufficient to heat the space)
    • Current temp= Heating Desired -3F= AuxHeating1 Trigger, where 3F is a tuner value
    • Current temp= Heating Desired -2F= AuxHeating1 off
    • Current temp= Heating Desired -4F= AuxHeating2 Trigger, where 4F is a tuner value
    • Current temp= Heating Desired -3F= AuxHeating2 off
  • water valve control deactivates to prevent overcooling. (Where the central plant is providing cold water)
  • Fan stages ramp up based on the Auxillary Heating stages.

Or

  • water valve control activates and follows the cooling loop output for ramping.
  • Zone gets the necessary cooling with cooling loop output. 
  • Fan controls also follow the cooling loop for their trigger.
  • AUX stages deactivate. 
Unoccupied Mode
  • Staged fan controls activate (If fan mode is auto). Else staged fan controls activate as per the user specified fan speed.

 

| Modes of Operation Based on User Intents

Heat Only Operation

If

Then

Th2 is more than the '2-pipe Fancoil Heating Threshold'(85) 

(Central plant provides   hot water)       

  • Zone gets the necessary heating with heating loop output.
  • Fan controls also follow the heating loop for their trigger.
  • AUX stages activate as per the below conditions (When the supply water temperature is not sufficient to heat the space)
    • Current temp= Heating Desired -3F= AuxHeating1 Trigger, where 3F is a tuner value
    • Current temp= Heating Desired -2F= AuxHeating1 off
    • Current temp= Heating Desired -4F= AuxHeating2 Trigger, where 4F is a tuner value
    • Current temp= Heating Desired -3F= AuxHeating2 off

Th2 is less than the '2-pipe Fancoil Cooling Threshold'(65)

(Central plant provides   cold water) 

  •  Zone gets the necessary heating with Auxillary stages activating as per the below conditions (When the supply water temperature is not sufficient to heat the space)
    • Current temp= Heating Desired -3F= AuxHeating1 Trigger, where 3F is a tuner value
    • Current temp= Heating Desired -2F= AuxHeating1 off
    • Current temp= Heating Desired -4F= AuxHeating2 Trigger, where 4F is a tuner value
    • Current temp= Heating Desired -3F= AuxHeating2 off
  • water valve control deactivates to prevent overcooling. (Where the central plant is providing cold water)
  • Fan stages ramps up based on the Auxillary Heating stages (if set to auto), else will follow user intent. 
Cool Only Operation

If

Then

Th2 is more than the '2-pipe Fancoil Heating Threshold'(85) 

(Central plant provides   hot water)       

  • Fan will be OFF (if set to auto) else will follow user intent.
  • AUX stages deactivate.
  • water valve control deactivates to prevent overheating, during a cooling operation.

Th2 is less than the '2-pipe Fancoil Cooling Threshold'(65)

(Central plant provides   cold water) 

  • water valve control activates and follows the cooling loop output for ramping.
  • Zone gets the necessary cooling with cooling loop output. 
  • Fan controls also follow the cooling loop for their trigger.
  • AUX stages deactivate.

| Controls and Triggers Strategy

Controls

Trigger Strategy

Auxiliary Heating Stages 

Auxiliary heating stages are triggered based on the below scenarios.

  • Current temp= Heating Desired -3F= AuxHeating1 Trigger, where 3F is a tuner value (auxHeating1Activate), and when Current temp= Heating Desired -2F= AuxHeating1 off
  • Current temp= Heating Desired -4F= AuxHeating2 Trigger, where 4F is a tuner value (auxHeating2Activate), and when Current temp= Heating Desired -3F= AuxHeating2 off.
Fan Stages

Fan stages trigger based on the fan loop output which is a result of cooling loop and heating loop outputs, during cooling and heating operation respectively.

Fan control configured as modulating using analog out the percentages for the low, medium, and high are altered to 70% 80%, and 100% respectively.

Fan stages during the aux heating are driven by aux heat stages, but along with the actual scaled fan stage, the lower stages are also triggered.

Higher stages of the fan along with the lower ones run if the mapped stages are not available, the system looks for the next higher fan stage along with the lower stages of.

Fan Enable

Fan enable is a provision introduced to enable additional fan control, which switches "ON" during the occupied schedule, and when any conditioning is happening during the unoccupied schedule.

Example:

  • Fan Enable is used in a modulating VFD-controlled fan, where the variable frequency drives need to be switched "ON" before ramping up and down the fan speeds.
  • It can also be put to use for additional fan control within a staged HVAC unit or a zone, which should remain "ON" during their occupied hours.

Note: Fan Enabled is not a control option for the Fan stages. the fan stages control needs to be mapped separately for the system to start conditioning. 

Occupied Enable  A relay mapped to Occupied Enable is "ON" whenever the zone is in an occupied schedule and "OFF" when any conditioning happens during an unoccupied schedule.
Humidifier 

A Relay mapped to the humidifier is turned on whenever the humidity level for the 2 Pipe Fan Coil Unit (2PFCU) drops below the target Minimum Inside Humidity, a tuner value.

 And shows the user a target humidity control in Zone Screen on CCU and Facilisight apps.

De Humidifier 

A Relay mapped to the dehumidifier is turned on whenever the humidity level for the 2 Pipe Fan Coil Unit (2PFCU) goes above the target Minimum Inside Humidity, a tuner value.

 And shows the user a target humidity control in Zone Screen on CCU and Facilisight apps.

Demand Control Ventilation (DCV)

The DCV control is used to control an independent damper for the ventilation of air into the zone.  based on the following additional parameters set during configuration.

  • zoneCO2DamperOpeningRate   
  • zoneCO2Threshold
  • zoneCO2Target

This allows for very granular control of the IAQ.

It is driven or triggered by the DCV Loop Output which is a resultant of the above-configured parameters.

Example:

During an occupied time

If the Zone CO2 value > zoneCO2Threshold then DCV damper control triggers based on the DCV loop output.

If the Zone CO2 value < zoneCO2Threshold there will be no DCV damper trigger, and the relay will be set to OFF.

Door/Window Sensing

The door/window sensors are used to automatically override the operation of a zone, for the presence of doors and windows in the zone, Where the door/window can be opened and there can be a loss of the actual conditioning that is in effect.

When the door/window sensor is a part of the Analog IN, a Voltage is detected, based on which the zone operations are overridden.

  • If the Voltage detected is less than 2.0V the door is in closed condition, and the zone enters the door/window closed state, and the zone operates normally.
  • If the Voltage detected is more than 2.0V the door is in open state condition, and the zone enters the door/window closed state, during which the heating, cooling, and demand ventilation are turned off.

For more information on the door and window sensor working refer HyperStat Installation

Note: If this option is enabled by the user, this affects the conditioning status of the entire zone if multiple modules are paired in the zone. 

Keycard Sensor

The Keycard sensors are also used to automatically override the operation of a zone, where when the key card is removed from the keycard slot in a room/zone, which means the occupant of the room is no longer in the room leading to loss of the actual conditioning that is in effect. Up to one keycard sensor can be connected for a zone.

When the Keycard sensor is a part of the Analog IN, a Voltage is detected, based on which the zone operations are overridden.

  • If the Voltage detected is less than 2.0V the Keycard switch is closed and the card is in the slot, and the zone operates normally or the zone enters into auto force occupied if the zone is in occupied or the unoccupied schedule respectively.
  • If the Voltage detected is more than 2.0V the Keycard switch is opened and the card is not in the slot, and the zone enters into unoccupied from forced occupied or zone enters into Key card auto away if the zone is in unoccupied or occupied schedule respectively.

For more information on the keycard sensor working refer HyperStat Installation

Note:  Keycard functioning is separate from the "Auto Away" toggle. There is no interlinking between keycard-based functioning and Occupancy sensor-based functioning.

Current Transformer

Current transformer is another analog input option in the profiles for HyperStat, it connects to a transformer in the circuit and simply measures the current consumption in the circuit.

For more information on the current transformers as Analog IN refer HyperStat Installation

Note: Each module configured can have upto 2 door/window sensors but sensor type keycard can only be one for the given equipment. If keycard is present, the zone is considered occupied by default.

| Configurations Confirmed

Considering the Auto-Away and Auto Occupied toggle is enabled, then the following are the relay mapping options available to select.

 

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Enabling the relay and configuration toggle button provides an option to set up the configuration parameters which can be further mapped to each relay and inputs.

Scroll further to view all the available options under the relays and inputs.

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It is to be noted that additional parameters are made available, only when DCV Damper is one of the Analog Outputs. The parameters for the same are discussed below.

Parameter Purpose Default Value Values in Drop Down
Analog Out at Min DCV Damper To set the minimum analog out value for modulating DCV Damper Control 2V Range from 0V to 10V in 1V increments
Analog Out at Max DCV Damper To set the maximum analog out values for modulating DCV Damper Control 10V Range from 0V to 10V in 1V increments
CO2 Damper Opening Rate To set damper opening rate based on the CO2 Thresholds 10% Range from 0% to 200% in 10% increments 

 

  • Click Set to confirm the parameters configured.

The configuration also provides an option to disable the targets and thresholds for the IAQ parameters CO2, VOC, and PM2.5 as below. Scroll further to view all the drop-down values under the CO2 Threshold and CO2 Target values.

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| IAQ Parameters Display Settings in the HyperStat Device

The profile also allows the user to set IAQ (Indoor Air Quality) parameters that can be displayed on the HyperStat device's home screen.                   

Note: Only two of the IAQ parameters can be set at a time, to be displayed in the HyperStat device's home screen, or none can be enabled. 

Before the parameters are enabled, the HyperStat device screen is showcased as below:

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When parameters are enabled, and thresholds set as below, the screen is displayed as

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The enabled parameter values and the threshold breach message are displayed on the HyperStat device's screen as below. 

 

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