MyStat Heat Pump Unit (HPU)

| Overview

The 75F MyStat Heat Pump Unit is a unique profile, that provides both heating and cooling conditioning.

Based on whether the unit is in the heating operation or cooling operation the reversing valve is set to reverse the direction of the flow of the refrigerant switching the condenser and the evaporator coil of the system to provide the necessary conditioning.

The reheat capability is enabled with the auxiliary heating stages which only gets triggered during the Auto and Heat Only mode when the compressor-provided heat is not sufficient (where additional heat is required).

The MyStat Heat Pump Unit (HPU) provides the flexibility to choose between fully modulating and staged equipment control. The possible equipment configurations include:

• 2 Stage Compressor Control
• 1 Stage auxiliary heating control
• 2 Stage Fan Speed Control
• Changeover (Type O or Type B)
• 1 Universal input
• 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 Heat Pump Unit 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	Compressor Stage 1	Compressor Stage 1 Compressor Stage 2 Aux Heating Fan Low Speed Fan High Speed Fan Enable Occupied Enable Humidifier Dehumidifier 0 - Energize in Cooling B - Energize in Heating Externally Mapped DCV Damper
Relay 2	To enable staged conditioning controls	Aux Heating
Relay 3	To enable staged conditioning controls	Fan Low Speed
Relay 4	To enable staged conditioning controls	0 - Energize in Cooling
Analog Out	To enable modulating conditioning controls	Compressor Speed	Compressor Speed 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/ OWI Sensor
Humidity	Input	MyStat/ OWI Sensor
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
Compressor Stage 1	Output	MyStat Relay
Compressor Stage 2	Output	MyStat Relay
Aux Heating Stage 1	Output	MyStat Relay
Fan Low Speed	Output	MyStat Relay
Fan High Speed	Output	MyStat Relay
Humidifier	Output	MyStat Relay
Dehumidifier	Output	MyStat Relay
Modulating Compressor Speed	Output	MyStat Analog Out
Modulating Fan Speed	Output	MyStat Analog Out
Modulating DCV Damper	Output	MyStat Analog Out
Airflow Temperature	Input	MyStat Thermistor
analogFanSpeedMultiplier	Tuner	1
auxHeating1Activate	Tuner	3F

 

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, 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

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	Then
The compressor stages with Fan stages meet the zone load	The HeatingLoopOutput is mapped to the Analog-based Compressor Speed/ relay-based Compressor Speed. The FanLoopOutput is enabled based on HeatingLoopOutput (FanLoopOutput= HeatingLoopOuptut* analogFanSpeedMultiplier(1)) the FanLoopOutput is mapped to the Analog- based / relay-based fan speeds.
The compressor stages with the fan stages do not meet the zone load	Then the Auxiliary heating is enabled.  Fan speeds are enabled based on the Auxiliary Heating.

 

• The dcvLoopOutput is disabled.

Pre-cooling:

• If the space temperature exceeds the occupied cooling temperature setpoint, the pre-conditioning shall initiate the morning pre-cooling via CoolingLoopOutput. The CoolingLoopOutput is mapped to the Analog-based Compressor Speed/ relay-based Compressor Speed.
• The FanLoopOutput is enabled based on CoolingLoopOutput (FanLoopOutput= CoolingLoopOuptut* analogFanSpeedMultiplier(1)) the FanLoopOutput is mapped to the Analog- based / relay-based fan speeds.
• The dcvLoopOutput is disabled.

Note:  Fan control (for user intent) is configured as modulating using analog out the percentages for the low, medium, and high are altered to 70% 80%, and 100% respectively. 

| 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 relay based fans.

During Heating:

• When the space current temperature falls below the HeatingDesiredTemperature the HeatingLoopOutput is enabled as below.

If	Then
The compressor stages with Fan stages meet the zone load	The HeatingLoopOutput is mapped to the Analog-based Compressor Speed/ relay-based Compressor Speed. The FanLoopOutput is enabled based on HeatingLoopOutput (FanLoopOutput= HeatingLoopOuptut* analogFanSpeedMultiplier(1)) the FanLoopOutput is mapped to the Analog- based / relay-based fan speeds.
The compressor stages with the fan stages do not meet the zone load	Then the Auxiliary heating is enabled. Fan speeds are enabled based on the Auxiliary Heating.

 

• When the space CO2 level is above the CO2 threshold set, the dcvLoopOutput is enabled with the dcvCalculatedDamperPos = (sensorMyStatCo2 - zoneCO2Threshold )/zoneCO2DamperOpeningRate, modulating between the analogOutxAtMinDCVDamperPos and analogOutxAtMaxDCVDamperPos

During Cooling:

• If the space temperature exceeds the occupied cooling temperature setpoint, the pre-conditioning shall initiate the morning pre-cooling via CoolingLoopOutput. The CoolingLoopOutput is mapped to the Analog-based Compressor Speed/ relay-based Compressor Speed.
• The FanLoopOutput is enabled based on CoolingLoopOutput (FanLoopOutput= CoolingLoopOuptut* analogFanSpeedMultiplier(1)) the FanLoopOutput is mapped to the Analog- based / relay-based fan speeds.
• When the space CO2 level is above the CO2 threshold set, the dcvLoopOutput is enabled with the dcvCalculatedDamperPos = (sensorMyStatCo2 - zoneCO2Threshold )/zoneCO2DamperOpeningRate, modulating between the analogOutxAtMinDCVDamperPos and analogOutxAtMaxDCVDamperPos

Note:  Fan control (for user intent) is configured as modulating using analog out the percentages for the low, medium, and high are altered to 70% 80%, and 100% respectively.

 

| 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, FanLoopOutput, and Auxiliary Heating Stages are disabled.

During Heating:

• When the space current temperature falls below the heating autoaway setback temperature, the HeatingLoopOutput is enabled as below.

If	Then
The compressor stages with Fan stages meet the zone load	The HeatingLoopOutput is mapped to the Analog-based Compressor Speed/ relay-based Compressor Speed. The FanLoopOutput is enabled based on HeatingLoopOutput (FanLoopOutput= HeatingLoopOuptut* analogFanSpeedMultiplier(1)) the FanLoopOutput is mapped to the Analog- based / relay-based fan speeds.
The compressor stages with the fan stages do not meet the zone load	Then the Auxiliary heating is enabled. Fan speeds are enabled based on the Auxiliary Heating.

During Cooling:

• If the space temperature exceeds the cooling autoaway setback temperature, the pre-conditioning shall initiate the morning pre-cooling via CoolingLoopOutput. The CoolingLoopOutput is mapped to the Analog-based Compressor Speed/ relay-based Compressor Speed.
• The FanLoopOutput is enabled based on CoolingLoopOutput (FanLoopOutput= CoolingLoopOuptut* analogFanSpeedMultiplier(1)) the FanLoopOutput is mapped to the Analog- based / relay-based fan speeds.
• The dcvLoopOutput is disabled.

Note:  Fan control (for user intent) is configured as modulating using analog out the percentages for the low, medium, and high are altered to 70% 80%, and 100% respectively.

| 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, FanLoopOutput, and Auxiliary Heating Stages are disabled.

During Heating:

• When the space's current temperature falls below the heating unoccupied setback temperature, the HeatingLoopOutput is enabled as below.

If	Then
The compressor stages with Fan stages meet the zone load	The HeatingLoopOutput is mapped to the Analog-based Compressor Speed/ relay-based Compressor Speed. The FanLoopOutput is enabled based on HeatingLoopOutput (FanLoopOutput= HeatingLoopOuptut* analogFanSpeedMultiplier(1)) the FanLoopOutput is mapped to the Analog- based / relay-based fan speeds.
The compressor stages with the fan stages do not meet the zone load	Then the Auxiliary heating is enabled. Fan speeds are enabled based on the Auxiliary Heating.

• The dcvLoopOutput is disabled

During Cooling:

• If the space temperature exceeds the cooling unoccupied setback temperature, the pre-conditioning shall initiate the morning pre-cooling via CoolingLoopOutput. The CoolingLoopOutput is mapped to the Analog-based Compressor Speed/ relay-based Compressor Speed
• The FanLoopOutput is enabled based on CoolingLoopOutput (FanLoopOutput= CoolingLoopOuptut* analogFanSpeedMultiplier(1)) the FanLoopOutput is mapped to the Analog- based / relay-based fan speeds.
• The dcvLoopOutput is disabled.

Note:  Fan control (for user intent) is configured as modulating using analog out the percentages for the low, medium, and high are altered to 70% 80%, and 100% respectively.

| 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 as below.

If	Then
The compressor stages with Fan stages meet the zone load.	The HeatingLoopOutput is mapped to the Analog-based Compressor Speed/ relay-based Compressor Speed. The FanLoopOutput is enabled based on HeatingLoopOutput (FanLoopOutput= HeatingLoopOuptut* analogFanSpeedMultiplier(1)) the FanLoopOutput is mapped to the Analog- based / relay-based fan speeds.
The compressor stages with the fan stages do not meet the zone load	Then the Auxiliary heating is enabled. Fan speeds are enabled based on the Auxiliary Heating.

• The dcvLoopOutput is disabled.

During Cooling:

• If the space temperature exceeds the occupied cooling temperature setpoint, the pre-conditioning shall initiate the morning pre-cooling via CoolingLoopOutput. The CoolingLoopOutput is mapped to the Analog-based Compressor Speed/ relay-based Compressor Speed
• The FanLoopOutput is enabled based on CoolingLoopOutput (FanLoopOutput= CoolingLoopOuptut* analogFanSpeedMultiplier(1)) the FanLoopOutput is mapped to the Analog- based / relay-based fan speeds.
• The dcvLoopOutput is disabled.

Note:  Fan control (for user intent) is configured as modulating using analog out the percentages for the low, medium, and high are altered to 70% 80%, and 100% respectively.

| Sequence of Operation During Emergency Conditioning

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
• Auxiliary Heating Stages
• 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

User intent Modes  & Operation based on Setpoint & Setback	Pre-Conditioning	Occupied	AutoAway	Unoccupied	Forced Occupied
Auto	(HeatingLoopOutput FanLoopOutput) / (HeatingLoop Output +Auxillary Heating Stages  FanLoopOutput) / (CoolingLoopOutput FanLoopOutput)	(HeatingLoopOutput FanLoopOutput) / (HeatingLoop Output +Auxillary Heating Stages  FanLoopOutput) dcvLoopOutput) / (CoolingLoopOutput FanLoopOutput) dcvLoopOutput	(HeatingLoopOutput FanLoopOutput)/ (HeatingLoop Output +Auxillary Heating Stages  FanLoopOutput) /  (CoolingLoopOutput FanLoopOutput)	(HeatingLoopOutput FanLoopOutput)/ (HeatingLoop Output +Auxillary Heating Stages  FanLoopOutput) / (CoolingLoopOutput FanLoopOutput)	(HeatingLoopOutput FanLoopOutput) / (HeatingLoop Output +Auxillary Heating Stages  FanLoopOutput) dcvLoopOutput/ (CoolingLoopOutput FanLoopOutput) dcvLoopOutput
Heat Only	(HeatingLoopOutput FanLoopOutput) / (HeatingLoop Output +Auxillary Heating Stages  FanLoopOutput)	(HeatingLoopOutput FanLoopOutput) / (HeatingLoop Output +Auxillary Heating Stages  FanLoopOutput) dcvLoopOutput	(HeatingLoopOutput FanLoopOutput) / (HeatingLoop Output +Auxillary Heating Stages  FanLoopOutput)	(HeatingLoopOutput FanLoopOutput) / (HeatingLoop Output +Auxillary Heating Stages  FanLoopOutput)	(HeatingLoopOutput FanLoopOutput) / (HeatingLoop Output +Auxillary Heating Stages  FanLoopOutput) dcvLoopOutput
Cool Only	CoolingLoopOutput FanLoopOutput	CoolingLoopOutput FanLoopOutput dcvLoopOutput	CoolingLoopOutput FanLoopOutput	CoolingLoopOutput FanLoopOutput	CoolingLoopOutput FanLoopOutput dcvLoopOutput
Off	All Loops Deactivated