FCU

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Description

The W7752 D, E, F, and G Controllers are communicating mains-powered Fan Coil Unit Controllers in the Excel 10 product line. They cover a wide range of fan coil control applications. The controllers can operate as stand-alone units or networked using the standard Echelon LONWORKS bus. Interfaces are provided for a wide range of actuator types. Heating systems can be water or electric, and cooling systems can be chilled water supply or compressors. Extensive timing and interlock features make the W7752 especially suitable for systems using electric heat and compressors.

Features

FCU Controller Models

The following table lists the FCU Controller models.

OS Number Power Input Reheat Relay
W7752D2xxx 230 VAC X
W7752E2xxx 230 VAC  
W7752F2xxx 115 VAC X
W7752G2xxx 115 VAC  

The W7752D,E,F and G are LonMark compliant Fan Coil Unit Controllers in the Excel 10 family product line. These controllers provide room temperature control for two and four pipe fan coil units with optional electric heating coils W7752D,F) and can control single, two or three speed fans. The controller is provided with default configuration settings from the factory and is fully operable on installation. Using standard Echelon configuration tools, the controller can be configured with job-specific settings. A variety of optional wall modules interface with the FCU controllers and provide any or all of the following: setpoint adjustment, fan speed adjustment, and occupancy bypass button. All wall modules include a space temperature sensor, however a remote C7068A return air sensor can also be used.

Supported Output Types

The following table lists the supported output types.

Ouput Options
Heating Floating, thermal, PWM, on/off, multi-stage electric
Cooling Floating, thermal, PWM, on/off, multi-stage compressor
Fan On/Off, 2-speed, 3-speed
Electric Reheat On/Off

Navigating to FCU Pages

Learn how to navigate to the FCU pages.

Sequences

Heat and cool sequences can be selected to be active or not active, giving a total of eight different sequence options (each can be with or without fan control)::

Modes of Operation

The controller has the following modes of operation.

This is the normal operating condition for a room or zone when it is occupied. The controller can be switched into this mode by a network command, by the room occupancy sensor, or by a bypass button on the wall module. In the occupied mode the fan is controlled by the setting of the fan speed switch on the wall module or by the control algorithm when the switch is set to "auto." The fan can be configured to remain on or turn off during the zero energy band.

The standby mode saves energy by reducing heating or cooling demand during periods where the room is temporarily unoccupied. In this mode the fan is switched off during the zero energy band.

This mode is used for longer unoccupied periods, such as at night or during weekends and holidays.

The controller is configured for window open detection, the controller automatically disables heat and cool control until the window is closed again. Frost protection remains active.

If the temperature drops below 46 Deg.F (8 Deg.C), the controller enables the heating circuit as frost protection.

When configured with an air flow detector, the controller protects equipment by disabling the system when the fan fails

The controller operates two-pipe FCUs configured with a changeover input.

Input/Output

Input Output Specifications

Inputs Function Characteristics
Digital Window/occupancy/changeover/air flow Closed <= 400 ohm, open >= 10K ohm
Analog/Digital
(Wall Module connection only)
Fan speed/Override Resistor Network
Analog Temperature Sensor 20K ohm NTC
Analog
(Wall Module connection only)
Setpoint adjustment 10k Ohm
Outputs    
Digital
(Wall Module connection only)
Override LED 0/5 VDC
Triac (2 pairs)
(See Supported Output Types table for options)
Heat and cool 24 VAC, 250 mA max continuous, 650 mA max surge (<=30 sec)
Relay (3) Fan Switching 20 to 253 VAC, 3A max
High Power relay
(W7725D, F only)
Electric heat (resistive load) 20 to 300 VAC, 10A max, 6A max