SmartStat- 4PIPE FCU (Fan Coil Unit)

| Overview

As the name suggests, a 4-pipe fan coil unit comprises 4 pipes, supporting two different coils. One favors the heating allowing a hot water supply into the heating coil, and the other favors the cooling, allowing a chilled water supply into the cooling coil. Along with the coils, a fan to run air over.

A fan runs air over the coil to convert it to conditioned air. The thermostat has control over whether to turn on the fan and at what speed and also which coil supply valve to turn on.

| How it Works.

The 75F SmartStat 4 Pipe Fan Coil unit is a unique profile, that provides both heating and cooling conditioning with,

3 Stage Fan Speed Control
Heating Valve Control
Cooling Valve Control
2 Thermistor inputs connecting to Airflow Temperature Sensor & Supply Water Temperature
Occupancy Sensing Control

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 are achieved.

Additionally, it also supports the Auto Force Occupied and Auto-Away occupancy-based controls.

| Application of Deadband and Hysteresis

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

| Wiring Diagram

| Configuration

Select the SmartStat option from the device screen.

Select 4 Pipe FCU from the module type.

The pairing options are displayed on the screen which provides the steps to successfully pair the device.

Click Pair to start the pairing.

Select the displayed Bluetooth address.

Enter the PIN displayed on the device and press Pair.

You can see the configuration screen for the 4 PIPE FCU with the following options available for configuration.

| Configuration Parameters

Once the SmartStat is paired as a 4 Pipe Fan Coil profile, you will need to enable the required configuration parameters as below, which define the physical characteristics of the device.

Parameters	Usage/Purpose/Trigger
Fan Medium Speed	Activated when space temp is 2 degrees less or 2 degrees more from the heating or cooling desired setpoint respectively.
Fan High Speed	Activated when space temp is 3 degrees less or 3 degrees more from the heating or cooling desired setpoint respectively.
Fan Low Speed	Activated when space temp is 1 degree less or 1 degree more from the heating or cooling desired setpoint respectively.
Water Valve - Energize in Heating	Activated when the central plant is in cooling, the zone demands heating.
Water Valve - Energize in Cooling	Controls the water valve to keep for the cooling coil input from the central plant.
Airflow Temperature Sensor	Enabled when an airflow temp sensor is used for the profile.
Supply Water Sensor (as an External 10k Temp Sensor)	Used to connect the supply water temperature sensor.
Enable Occupancy Setting	Select if you would like to use the Occupancy-based setpoint control.

Test Signal

This is used for troubleshooting and testing the equipment if the configuration and the field setup are in sync, and the device is communicating properly with the controlled equipment. Also at any point, you can override the value of the output the algorithm decides.

We can use the test signal for relays to turn them on or for analog out to ramp up and see if the equipment works according to commands from the device.

Test Signal Time Out

once enabled it will be active for an hour if the screen is not changed, after an hour of no interaction on the screen. zone screen displays and the test signal will be OFF.

If the screen changes from the test signal configuration screen it will be timed out in one minute (time for the algorithm to run next).

Enable the required parameters as below.

Click Set to confirm the parameters configured.

| Post Configuration

The zones paired with 4PIPE FCU profile is displayed in the CCU as below.

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

| Fan Modes

4 Pipe FCU profile 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

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

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

| Modes of Operation Based on User Intents

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

Mode

Operations

Off Mode

All relays associated with multiple inputs will be non-functional and set OFF

Heat Only Operation

Auxillary heating control is deactivated.
Water control is deactivated (Fan mode is off)

If	Then
The current temperature is less than the setpoint.	Heating Water valve activates when the current temperature is 1F less than the desired temperature. Fan stages activate. The Fan low, medium, and high activate when the current temperature is 1F, 2F, and 3F, less than the heating desired temperature. Fan stages (Low, medium, and High) deactivate when the current temperature is 0.5F, 1F, and 2F, less than the heating desired temperature.
The current temperature is more than the setpoint.	Fan stages deactivate if the fan mode is Auto. Else the fan stages activate as per the user-specified fan speeds. Heating and cooling Water valve control deactivate.

Cool Only Operation

If	Then
The current temperature is more than the setpoint.	Cooling Water valve activates when the current temperature is 1F more than the cooling desired temperature. Fan stages activate. The Fan low, medium, and high activate when the current temperature is 1F, 2F, and 3F, more than the cooling desired temperature. Fan stages (Low, medium, and High) deactivate when the current temperature is 0.5F, 1F, and 2F, more than the cooling desired temperature.
The current temperature is less than the setpoint.	Fan stages deactivate if the fan mode is Auto. Else the fan stages activate as per the user-specified fan speeds. Heating and cooling Water valve controls deactivate.

Auto Mode

Then

The current temperature is less than the setpoint.

Operate relays in heat-only mode.

The current temperature is more than the setpoint.

Operate relays in cool-only mode.

Setback Mode

During the setback mode the temperature drifts further away from the setpoint to save energy
information in the tool.

If	Then
the module is controlling heating-only equipment or mode is set to heat only the	the setback temperature is lower than desired as determined by tuners.
the module is controlling cooling only equipment or mode is set to cool only if the	the setback temperature is higher than desired as determined by tuners.
the module is assigned to equipment capable of heating and cooling,	Temp will be higher than or lower than the desired temp, the system follows the setback for cooling and heating equipment respectively determined by tuners.

| Equip Graphics for Smartstat 4Pipe FCU

Equipment graphics is available for all the terminal profiles. It provides a graphical representation of system-level equipment and enables monitoring of key point parameters associated with terminal profiles.

Smartstat 4 Pipe.png

The highlighted list of points is predefined for visualization alongside the graphic for the respective profile.

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