Description

The DNT-T221BX-FCU is an intelligent room thermostat package for fancoil units with multi-speed fans. It consists of an intelligent LCD thermostat (DNT-T221BX) for control and BACnet communications, and an analog to binary output for fan control. The DNT-T221BX communicates on Delta’s LINKnet network or directly on a BACnet MS/TP network. It displays a wide-range of digital or analog values including set- points, temperature, heating and cooling status, fan speed and valve position. 

Application

The DNT-T221BX-FCU is designed to be a low cost solution for control of a Fan Coil Unit utilizing a multi- speed fan. 

Features (BACstat)

—Native BACnet™ firmware
—BACnet MS/TP or LINKnet communications —Configurable 3-value, 96 segment, LCD display —4 Configurable push buttons
—Controller firmware can be flash loaded over the

network
—Network termination is jumper selectable on each

device
—Derived Network Addressing (DNA) for simple

integration into a standard network architecture —Field selectable applications
—Service port

Features (Relay Board)

—5 Output board for multi-speed fans and 2 and 4 pipe configurations

—Diagnostic LED’s
—Power
—Fan Speed (Hi, Medium, Lo) —Cooling Mode
—Heating Mode

—Step Down Transformer

The DNT-T221BX-FCU has a built-in algorithm specially designed for this purpose. The controller can be used with single stage digital heat or cool or in a switched mode. 

Specifications BACstat

BACnet Device Profile

BACnet Application Specific Controller

(B-ASC)

LCD

3-value and various icons (96 total segments)

with optional backlighting Temperature Sensor

Thermistor Input - 10k½ at 77°F (25°C) Accuracy +/-0.36°F from 32-158°F

(+/- 0.2°C from 0-70°C)

Display resolution of 0.1°

Stability 0.24°F over 5 years (0.13°C) Inputs

Space temperature input (internal)

Occupancy Input - 10 bit (0-5v, 0-10v, 10k½) Window Contact Input - 10 bit (0-5v, 0-10v,

10k½)

Supply air temperature - 10 bit (0-5v, 0-10v,

10k½)**
Discharge water temperature - 10 bit (0-5v, 0

10v, 10k½)* Outputs

Fan speed - 0-10 VDC @ 20mA maximum Heating /Cooling (normally closed) - 0-10 VDC

@ 20mA maximum
Electric Reheat - triac (supporting binary, pwm,

tri-state )*
Valve Changeover - triac (supporting direct or

reverse )**

*2 Pipe configuration only

**4 Pipe configuration only