| Overview
The 75F MyStat 4 Pipe Fan Coil Unit (4PFCU) is a unique profile that provides both heating and cooling conditioning.
Based on the system's conditioning and fan modes and the temperature of the supply water from the chiller, the heating and cooling operations are triggered, and the corresponding actions and conditioning are achieved.
The reheat capability is enabled with the auxiliary heating stage, which is only triggered during Auto and Heat Only mode (where additional heat is required).
The MyStat 4 Pipe Fan Coil Unit (4PFCU) provides the flexibility to choose between fully modulating and staged equipment control. The possible equipment configurations include:
- Two-Stage Fan Speed Control
- Single-stage auxiliary heating control
- Single-stage water valve control
- Single-Stage DCV Damper Control
- Humidifier & Dehumidifier Controls
- Fan Enable and Occupied Enable
- Modulating fan, water valve, and DCV damper control
- Universal Input for supply water temperature measurement
| Wiring
MyStat V1 Wiring
MyStat V2 Wiring
| Configuration Steps
Once the zone is added
- Select the zone
- Click Pair Module.
- Click MS MyStat from the select device type.
The Mystat version selection window displays
- Select the version of the MyStat based on the back plate details of the MyStat
- Click Next to proceed.
Note: Based on the Mystat version selection, the configuration parameters in the configuration screen would differ.
- 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.
The profile configuration screen is displayed, as shown below.
Note: Based on the Mystat version selection, the configuration parameters in the configuration screen would differ.
Mystat V1 Configuration
Mystat V2 Configuration
| MyStat V1 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 Water Valve |
Fan Low Speed Fan High Speed Aux Herating Cooling Water Valve Heating Water Valve Fan Enable Occupied Enable Humidifier Dehumidifier Externally Mapped DCV Damper Fan Low Speed - Ventilation |
Relay 2 |
To enable staged conditioning controls |
Heating Water Valve |
|
Relay 3 |
To enable staged conditioning controls |
Fan Low Speed |
|
Relay 4 |
To enable staged conditioning controls |
Aux Heating |
|
Analog-Out |
To enable modulating conditioning controls |
Cooling Modulating Valve |
Cooling Modulating Valve Heating Modulating Valve Fan Speed Externally Mapped- Analog DCV Modulating Damper |
Universal- In |
To enable the supply water temperature measurement |
Discharge Air Temperature |
NA |
Space & Desired Temperature options are made available to enable display on the homescreen.
Installer Access and Conditioning Mode & Fan Access PIN locks are also available from the configuration screen.
| MyStat V2 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 |
Water Valve |
Fan Low Speed Fan High Speed Aux Herating Cooling Water Valve Heating Water Valve Fan Enable Occupied Enable Humidifier Dehumidifier Externally Mapped DCV Damper Fan Low Speed - Ventilation
|
Relay 2 |
To enable staged conditioning controls |
Aux Heating |
|
Relay 3 |
To enable staged conditioning controls |
Fan Low Speed |
|
Universal- Out 1 |
To enable staged conditioning controls |
Fan Low Speed |
Relay-Based Controls Fan Low Speed Fan High Speed Aux Herating Cooling Water Valve Heating Water Valve Fan Enable Occupied Enable Humidifier Dehumidifier Externally Mapped- Relay DCV Damper Fan Low Speed - Ventilation Analog Out-Based Controls Cooling Modulating Valve Heating Modulating Valve Fan Speed Externally Mapped- Analog DCV Modulating Damper |
Universal- Out 2 |
To enable modulating conditioning controls |
Fan High Speed |
|
Universal In |
To enable the supply water temperature measurement |
Supply Water Temperature |
NA |
Space & Desired Temperature options are made available to enable display on the homescreen.
Installer Access and Conditioning Mode & Fan Access PIN locks are also available from the configuration screen.
- Configure the required parameters.
Mystat Version 1 Configured
Mystat Version 2 Configured
For More information on the jumper settings for the Mystat, refer to Mystat Jumper Settings
- 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 Onboard |
| Humidity | Input | MyStat Onboard |
| 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 |
| Auxiliary Heating | Output | Mystat Relay |
| Water Valve | Output | MyStat Relay |
| Fan Low Speed | Output | MyStat Relay |
| Fan High Speed | Output | MyStat Relay |
| Humidifier | Output | MyStat Relay |
| Dehumidifier | Output | MyStat Relay |
| Modulating Water Valve | Output | MyStat Analog Out |
| Modulating Fan Speed | Output | MyStat Analog Out |
| Modulating DCV Damper | Output | MyStat Analog Out |
| Cooling Water Temperature | Input | MyStat Universal In |
| Heating Water Temperature | Input | MyStat Universal In |
| waterValveSampleingWaitTime | Tuner | 58 Mins |
| waterValveSamplingOnTime | Tuner | 2 Mins |
|
waterValveSampling DuringLoopDeadband WaitTime |
Tuner | 5 Mins |
|
waterValveSamplingDuring LoopDeadband OnTime |
Tuner | 2 Mins |
auxHeatingActivate |
Tuner | 3F |
| 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
Warm-up:
- If the space temperature is below the occupied heating temperature setpoint, the pre-conditioning shall initiate the morning warm-up via HeatingLoopOutput / Auxiliary Heating Stages, as below.
| If | Then | ||
Supply water temperature is above the 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
|
||
Supply water temperature is below the 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
|
||
Supply water temperature is greater than 2-pipe Fancoil Heating Threshold (85F) (Tuner) & less than 2-pipe Fancoil Cooling Threshold (65F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
||
Supply water temperature is between 2-pipe Fancoil Cooling Threshold (65F) & 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
- The dcvLoopOutput is disabled.
Pre-cooling:
- If the space temperature is below the occupied heating temperature setpoint, the pre-conditioning shall initiate the morning pre-cooling via CoolingLoopOutput, as below.
| If | Then | ||
Supply water temperature is below the 2-pipe Fancoil Cooling Threshold (65F) (Tuner) |
|
||
Supply water temperature is above the 2-pipe Fancoil Heating Threshold (65F) (Tuner) |
|
||
Supply water temperature is greater than 2-pipe Fancoil Heating Threshold (85F) (Tuner) & less than 2-pipe Fancoil Cooling Threshold (65F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
||
Supply water temperature is between 2-pipe Fancoil Cooling Threshold (65F) & 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
- The dcvLoopOutput is disabled.
| 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:
During Heating:
- When the space current temperature falls below the HeatingDesiredTemperature the HeatingLoopOutput is enabled as below.
| If | Then | ||
Supply water temperature is above the 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
|
||
Supply water temperature is below the 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
|
||
Supply water temperature is greater than 2-pipe Fancoil Heating Threshold (85F) (Tuner) & less than 2-pipe Fancoil Cooling Threshold (65F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
||
Supply water temperature is between 2-pipe Fancoil Cooling Threshold (65F) & 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
- When the space CO2 level is above the CO2 threshold set, the dcvLoopOutput is enabled with the dcvCalculatedDamperPos = (sensorHyperStatCo2 - zoneCO2Threshold )/zoneCO2DamperOpeningRate, modulating between the analogOutxAtMinDCVDamperPos and analogOutxAtMaxDCVDamperPos
During Cooling:
- When the space current temperature is above the Cooling Desired Temperature the CoolingLoopOutput is enabled as below.
| If | Then | ||
Supply water temperature is below the 2-pipe Fancoil Cooling Threshold (65F) (Tuner) |
|
||
Supply water temperature is above the 2-pipe Fancoil Heating Threshold (65F) (Tuner) |
|
||
Supply water temperature is greater than 2-pipe Fancoil Heating Threshold (85F) (Tuner) & less than 2-pipe Fancoil Cooling Threshold (65F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
||
Supply water temperature is between 2-pipe Fancoil Cooling Threshold (65F) & 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
- When the space CO2 level is above the CO2 threshold set, the dcvLoopOutput is enabled with the dcvCalculatedDamperPos = (sensorHyperStatCo2 - zoneCO2Threshold )/zoneCO2DamperOpeningRate, modulating between the analogOutxAtMinDCVDamperPos and analogOutxAtMaxDCVDamperPos
| 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, Auxiliary Heating Stages & CoolingLoopOutput, are disabled.
During Heating:
- When the space current temperature falls below the heating autoaway setback temperature, the HeatingLoopOutput is enabled as below.
| If | Then | ||
Supply water temperature is above the 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
|
||
Supply water temperature is below the 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
|
||
Supply water temperature is greater than 2-pipe Fancoil Heating Threshold (85F) (Tuner) & less than 2-pipe Fancoil Cooling Threshold (65F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
||
Supply water temperature is between 2-pipe Fancoil Cooling Threshold (65F) & 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
During Cooling:
- When the space current is above the cooling the CoolingLoopOutput is enabled as below.
| If | Then | ||
Supply water temperature is below the 2-pipe Fancoil Cooling Threshold (65F) (Tuner) |
|
||
Supply water temperature is above the 2-pipe Fancoil Heating Threshold (65F) (Tuner) |
|
||
Supply water temperature is greater than 2-pipe Fancoil Heating Threshold (85F) (Tuner) & less than 2-pipe Fancoil Cooling Threshold (65F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
||
Supply water temperature is between 2-pipe Fancoil Cooling Threshold (65F) & 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
| 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, Auxilliary Heating Stages & CoolingLoopOutput, are disabled
During Heating:
- When the space's current temperature falls below the heating the HeatingLoopOutput is enabled as below.
| If | Then | ||
Supply water temperature is above the 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
|
||
Supply water temperature is below the 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
|
||
Supply water temperature is greater than 2-pipe Fancoil Heating Threshold (85F) (Tuner) & less than 2-pipe Fancoil Cooling Threshold (65F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
||
Supply water temperature is between 2-pipe Fancoil Cooling Threshold (65F) & 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
- The dcvLoopOutput is disabled
During Cooling:
- When the space current temperature is above the cooling the CoolingLoopOutput is enabled as below.
| If | Then | ||
Supply water temperature is below the 2-pipe Fancoil Cooling Threshold (65F) (Tuner) |
|
||
Supply water temperature is above the 2-pipe Fancoil Heating Threshold (65F) (Tuner) |
|
||
Supply water temperature is greater than 2-pipe Fancoil Heating Threshold (85F) (Tuner) & less than 2-pipe Fancoil Cooling Threshold (65F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
||
Supply water temperature is between 2-pipe Fancoil Cooling Threshold (65F) & 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
- The dcvLoopOutput is disabled.
| 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 | ||
Supply water temperature is above the 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
|
||
Supply water temperature is below the 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
|
||
Supply water temperature is greater than 2-pipe Fancoil Heating Threshold (85F) (Tuner) & less than 2-pipe Fancoil Cooling Threshold (65F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
||
Supply water temperature is between 2-pipe Fancoil Cooling Threshold (65F) & 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
- The dcvLoopOutput is disabled.
During Cooling:
- When the space current temperature is above the Cooling Desired Temperature the CoolingLoopOutput is enabled as below.
| If | Then | ||
Supply water temperature is below the 2-pipe Fancoil Cooling Threshold (65F) (Tuner) |
|
||
Supply water temperature is above the 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
|
||
Supply water temperature is greater than 2-pipe Fancoil Heating Threshold (85F) (Tuner) & less than 2-pipe Fancoil Cooling Threshold (65F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
||
Supply water temperature is between 2-pipe Fancoil Cooling Threshold (65F) & 2-pipe Fancoil Heating Threshold (85F) (Tuner) |
During this condition, To ensure that the water is flowing and the water temperature is not measured for stagnant water, the Water Sampling Process is enabled, as below.
|
- The dcvLoopOutput is disabled.
| Sequence of Operation During Emergency Conditioning
When the building limits are violated, and the recorded temperature is within the building limit plus leeway the conditioning will happen in the direction of the 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
- 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.
| Control Mode Summary
|
User Intent Modes & Operation based on Setpoint & Setback |
Pre-Conditioning | Occupied | AutoAway | Unoccupied | Forced Occupied |
| Auto |
(HeatingLoopOutput FanLoopOutput) / (HeatingLoop Output + Auxiliary Heating FanLoopOutput) / (CoolingLoopOutput FanLoopOutput) |
(HeatingLoopOutput FanLoopOutput) / (HeatingLoop Output + Auxillary Heating FanLoopOutput) dcvLoopOutput) / (CoolingLoopOutput FanLoopOutput) dcvLoopOutput |
(HeatingLoopOutput FanLoopOutput)/ (HeatingLoop Output + Auxillary Heating FanLoopOutput) / (CoolingLoopOutput FanLoopOutput) |
(HeatingLoopOutput FanLoopOutput)/ (HeatingLoop Output + Auxillary Heating FanLoopOutput) / (CoolingLoopOutput FanLoopOutput) |
(HeatingLoopOutput FanLoopOutput) / (HeatingLoop Output + Auxillary Heating FanLoopOutput) dcvLoopOutput/ (CoolingLoopOutput FanLoopOutput) dcvLoopOutput |
| Heat Only |
(HeatingLoopOutput FanLoopOutput) / (HeatingLoop Output + Auxillary Heating FanLoopOutput) |
(HeatingLoopOutput FanLoopOutput) / (HeatingLoop Output + Auxillary Heating FanLoopOutput) dcvLoopOutput |
(HeatingLoopOutput FanLoopOutput) / (HeatingLoop Output + Auxillary Heating FanLoopOutput) |
(HeatingLoopOutput FanLoopOutput) / (HeatingLoop Output + Auxillary Heating FanLoopOutput) |
(HeatingLoopOutput FanLoopOutput) / (HeatingLoop Output + Auxillary Heating FanLoopOutput) dcvLoopOutput |
| Cool Only |
CoolingLoopOutput FanLoopOutput |
CoolingLoopOutput FanLoopOutput dcvLoopOutput |
CoolingLoopOutput FanLoopOutput |
CoolingLoopOutput FanLoopOutput |
CoolingLoopOutput FanLoopOutput dcvLoopOutput |
| Off | All Loops Deactivated |
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