MyStat Conventional Package Unit (CPU)

| Overview

The 75F MyStat Conventional Package Unit profile is a standalone profile that provides heating and cooling equipment controls for conditioning.

The Mystat provides the flexibility to choose between fully modulating and staged equipment control. Possible equipment configurations include:

• 2 Stages of cooling equipment control
• 2 Stages of heating equipment control
• 2 Stages of fan speed control
• Linear and Staged Fans for cooling and heating equipment control
• 1 Universal inputs
• Fan Enabled and Occupied Enable
• Humidifier & Dehumidifier Controls

| Wiring

 

| Configuration Steps

Once the zone is added

• Select the zone
• Click Pair Module.

• Click MS MyStat from the select device type.

• Click 2 Pipe FCU from the select module type screen

• Take note of the steps pair on the device.
• Click Pair

• Set the MyStat to pairing mode, broadcasting the MAC address.
• Select the broadcasted MAC address.

Alternatively, you can also pair the Mystat manually. For more information on manual pairing refer to Alternate/ Manual Pairing for MyStat

• Enter the PIN displayed on the device UI into the CCU window.
• Click Pair to complete the pairing process.

The profile configuration screen is displayed, as shown below.

 

| Configuration Parameters

Parameter	Purpose	Default Value	Values in the drop-down list
Temperature Offset	To set the temperature offset value for the profile.	0 (°F)	Range from -10 to + 10 in .1 increments
Auto Force Occupied	To enable Auto force occupied Note: Auto Forced occupied/forced occupied and Auto-Awayc cannot work together.	Disabled	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 controls	Cooling Stage 1	Cooling Stage 1 Cooling Stage 2 Heating Stage 1 Heating Stage 2 Fan Low Speed Fan High Speed Fan Enable Occupied Enable Humidifier Dehumidifier Externally Mapped DCV Damper
Relay 2	To enable staged conditioning controls	Fan Low Speed
Relay 3	To enable staged conditioning controls	Heating Stage 1
Relay 4	To enable staged conditioning controls	Fan High Speed
Analog Out	To enable modulating conditioning controls	Water Modulating Valve	Cooling Linear Fan Speed Heating Staged Fan Speed Externally Mapped DCV Modulating Damper
Universal In	To enable the supply water temperature measurement	Key Card Sensor (AI)	Supply Air Temperature Generic Alarm NO Generic Alarm NC Key Card Sensor (AI) Door/Window (N/C) - Title 24 Door/Window (AI) - Title 24

• Click Save to complete the configuration.

| Control System Object List

Object Name	Type	Input/Output Type/Default Value
Heating Desired Temp	User Intent	NA
Cooling Desired Temp	User Intent	NA
Current Temp	Input	MyStat
Humidity	Input	MyStat
User Cooling Max Limit	User Intent	NA
User Cooling Min Limit	User Intent	NA
User Heating Max Limit	User Intent	NA
User Heating Max Limit	User Intent	NA
Conditioning Mode	User Intent	NA
Operation Mode	Input	NA
Fan Mode	User Intent	NA
Occupancy Mode	Input	MyStat Onboard
Cooling Stage 1	Output	MyStat Relay
Cooling Stage 2	Output	MyStat Relay
Fan Low Speed	Output	MyStat Relay
Fan High Speed	Output	MyStat Relay
Heating Stage 1	Output	MyStat Relay
Heating Stage 2	Output	MyStat Relay
Fan Enabled	Output	MyStat Relay
Humidifier	Output	MyStat Relay
Dehumidifier	Output	MyStat Relay
Modulating Cooling	Output	MyStat AnalogOut
Modulating Heating	Output	MyStat AnalogOut
Modulating Linear Fan Speed	Output	MyStat AnalogOut
Modulating Staged Fan Speed	Output	MyStat AnalogOut
Keycard Sensor	Input	MyStat Analog In
Door/Window Sensor	Input	MyStat Analog In
analogFanSpeedMultiplier	Tuner	1
standalonehumidityHyteresis	Tuner	5 %RH

 

Note: For a comprehensive list of tuners and their details, refer tothe  Tuners Complete List

 

| Sequence of Operation

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

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

Warm-up:

• • If the space temperature is below the occupied heating temperature setpoint, the pre-conditioning shall initiate the morning warm-up via HeatingLoopOutput
  • The FanLoopOutput is enabled based on HeatingLoopOutput (FanLoopOutput= HeatingLoopOuptut* analogFanSpeedMultiplier(1))
  • The DCVLoopOutput based on the zone CO2 levels is disabled if configured.

Pre-cooling:

• • Suppose the space temperature is above the occupied space cooling temperature setpoint,  the pre-conditioning shall initiate the morning pre-cooling via CoolingLoopOutpu
  • The FanLoopOutput is enabled based on HeatingLoopOutput (FanLoopOutput= HeatingLoopOuptut* analogFanSpeedMultiplier(1))
  • The DCVLoopOutput based on the zone CO2 levels is disabled if configured.

| 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 fan speed is maintained, and the minimum fan analog voltages are set to 2V (customizable) for linear fans, and a recirculation fan speed voltage for staged fans.

During Heating:

• • When the space current temperature falls below the Heating Desired Temperature the HeatingLoopOutput is enabled. based on the difference in the space current temperature and heating desired temperature.
  • The FanLoopOutput is enabled based on HeatingLoopOutput (FanLoopOutput= HeatingLoopOuptut* analogFanSpeedMultiplier(1))

During Cooling:

• • When the space current temperature is above the Cooling Desired Temperature the CoolingLoopOutput is enabled, based on the difference in the space current temperature and cooling desired temperature.
  • The FanLoopOutput is enabled based on CoolingLoopOutput (FanLoopOutput= CoolingLoopOuptut* analogFanSpeedMultiplier(1))
  • When the space CO2 level is above the CO2 threshold set, the dcvLoopOutput is enabled with the dcvCalculatedDamperPos is determined by the loop calculated using the  MyStat Co2 sensor & zoneCO2Threshold, modulating between the analogOutxAtMinDCVDamperPos and analogOutxAtMaxDCVDamperPos

•  

Humidifier:

• • The humidifier shall modulate to maintain a return air humidity setpoint of 45% (adjustable), subject to the duct's high limit setpoint of 90% (adjustable). Humidification shall be locked out whenever the fan is de-energized or the duct humidity exceeds the high limit setpoint.

| 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:

• • FanLoopOutput, HeatingLoopOutput, & CoolingLoopOutput, are disabled

During Heating:

• • When the space current temperature falls below the heating autoaway setback temperature, the HeatingLoopOutput is enabled. based on the difference in the space's current temperature and the heating autoaway setback temperature.
  • The FanLoopOutput is enabled based on HeatingLoopOutput (FanLoopOutput= HeatingLoopOuptut* analogFanSpeedMultiplier(1))
  • The DCVLoopOutput based on the zone CO2 levels is disabled if configured.

During Cooling:

• • When the space current is above the cooling autoaway setback temperature, the CoolingLoopOutput is enabled. based on the difference in the space's current temperature and the cooling autoaway setback temperature
  • The FanLoopOutput is enabled based on CoolingLoopOutput (FanLoopOutput=CoolingLoopOuptut* analogFanSpeedMultiplier(1))
  • The DCVLoopOutput based on the zone CO2 levels is disabled if configured.

| 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:

• FanLoopOutput, HeatingLoopOutput, & CoolingLoopOutput, are disabled

During Heating:

• • When the space current temperature falls below the heating unoccupied setback temperature, the HeatingLoopOutput is enabled. based on the difference in the space's current temperature and the heating unoccupied setback temperature.
  • The FanLoopOutput is enabled based on HeatingLoopOutput (FanLoopOutput= HeatingLoopOuptut* analogFanSpeedMultiplier(1))
  • The DCVLoopOutput based on the zone CO2 levels is disabled if configured.

During Cooling:

• • When the space current temperature is above the cooling unoccupied setback temperature, the CoolingLoopOutput is enabled. based on the difference in the space's current temperature and the cooling unoccupied setback temperature.
  • The FanLoopOutput is enabled based on CoolingLoopOutput (FanLoopOutput=CoolingLoopOuptut* analogFanSpeedMultiplier(1))
  • The DCVLoopOutput based on the zone CO2 levels is disabled if configured.

| 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 FanLoopOutput is enabled regardless of no conditioning.

During Heating:

• • When the space current temperature falls below the Heating Desired Temperature the HeatingLoopOutput is enabled. based on the difference in the space current temperature and heating desired temperature.
  • The FanLoopOutput is enabled based on HeatingLoopOutput (FanLoopOutput= HeatingLoopOuptut* analogFanSpeedMultiplier(1))
  • When the space CO2 level is above the CO2 threshold set, the dcvLoopOutput is enabled with the dcvCalculatedDamperPos is determined by the loop calculated using the  sensor MyStatCo2 & zoneCO2Threshold, modulating between the analogOutxAtMinDCVDamperPos and analogOutxAtMaxDCVDamperPos

During Cooling:

• • When the space current temperature is above the Cooling Desired Temperature the CoolingLoopOutput is enabled, based on the difference in the space current temperature and cooling desired temperature.
  • The FanLoopOutput is enabled based on CoolingLoopOutput (FanLoopOutput= CoolingLoopOuptut* analogFanSpeedMultiplier(1))
  • When the space CO2 level is above the CO2 threshold set, the dcvLoopOutput is enabled. based on the following if enabled.
  • If the Zone CO2 value > zoneCO2Threshold then the 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.
  • When the space CO2 level is above the CO2 threshold set, the dcvLoopOutput is enabled with the dcvCalculatedDamperPos is determined by the loop calculated using the   MyStatCo2 & zoneCO2Threshold, modulating between the analogOutxAtMinDCVDamperPos and analogOutxAtMaxDCVDamperPos

| Sequence of Operation During Emergency Dead

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

| Sequence of Operation During Temp Dead

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

• • CoolingLoopOutput
  • HeatingLoopOutput
  • FanLoopOutput
  • dcvLoopOutput

| Humidifier Control

The humidifier is turned ON whenever the humidity level for the system drops below the targetMinInsideHumidty set. The humidifier will be turned OFF after being turned on when the humidity levels go humidityHysteresis above the targetMinInsideHumidty. Humidity control will not be maintained during UNOCCUPIED or VACATION modes.

| DeHumidifier Control

If the dehumidifier is selected, it turns ON whenever the humidity level for the system goes above the targetMaxInsideHumidty set. The dehumidifier will be turned OFF after being turned on when the humidity drops humidityHysteresis below the targetMaxInsideHumidty. Dehumidifier control will not be maintained during UNOCCUPIED or VACATION modes.

Note: The humidity level for the system is either the average level reported by all the zones serviced by the RTU/AHU.

| Control Mode Summary

Modes &  Operation	Pre-Conditioning	Occupied	AutoAway	Unoccupied	Forced Occupied
Auto	(HeatingLoopOutput  FanLoopOutput) / (CoolingLoopOutput FanLoopOutput	(HeatingLoopOutput FanLoopOutput dcvLoopOutput) / (CoolingLoopOutput FanLoopOutput dcvLoopOutput	(HeatingLoopOutput FanLoopOutput) /  (CoolingLoopOutput FanLoopOutput)	(HeatingLoopOutput FanLoopOutput) / (CoolingLoopOutput FanLoopOutput	(HeatingLoopOutput FanLoopOutput dcvLoopOutput) / (CoolingLoopOutput FanLoopOutput dcvLoopOutput)
Heat Only	HeatingLoopOutput FanLoopOutput	HeatingLoopOutput FanLoopOutput dcvLoopOutput	HeatingLoopOutput FanLoopOutput	HeatingLoopOutput FanLoopOutput	HeatingLoopOutput FanLoopOutput dcvLoopOutput
Cool Only	CoolingLoopOutput FanLoopOutput	CoolingLoopOutput FanLoopOutput dcvLoopOutput	CoolingLoopOutput FanLoopOutput	CoolingLoopOutput FanLoopOutput	CoolingLoopOutput FanLoopOutput dcvLoopOutput
Off	All Loops Deactivated

 

| Pointers that Need Attention

• When the Fan Enabled is configured alongside the AnalogOut-based Staged fan speeds, or Relay-based fan speeds.

• The minimum Fan speed in an Analog-based fan configuration, or low fan speed in a Relay-based fan configuration is turned ON when the Fan loop output is <10% without considering the relay activation hysteresis.

When the Door/Window sensor is enabled, A Minimum fan speed is operated when the door/window is open, and conditioning will be OFF.

• In an Analog-based fan configuration, the Fan is operated at the AnalogoutatMin, and in a staged fan speed configuration the Fan is operated at the AnalogOutatRecirculate speed. 
• A tuner parameter Minfanruntimepostconditioning defines the period for which the Last known fan speed, in an Analog-based fan configuration / minimum fan speed in a Relay-based fan configuration, needs to run after the conditioning is turned off.