BASstat Series BAST-421 Modulating Thermostats

Product Overview

The BASstat series of BACnet-compliant wired or wireless communicating thermostats ensure effortless integration into BACnet/IP (Wi-Fi) or BACnet MS/TP (EIA-485) networks. These thermostats are suited for modulated heating, cooling, and ventilation with analog output control in 4-pipe applications such as Fan Coil Units (FCU) or Air Handlers. A configurable control algorithm allows adaptability to the specific application. This adaptive algorithm applied to the modulated valve control saves energy and ensures comfort for the occupants. Three sensing options are available: built-in temperature sensor, input for remote temperature sensor, or temperature override network command from Building Automation System. Occupancy status can be set from thermostat buttons, a wired ESI input, or over the BACnet network. Thermostat buttons are optionally lockable to prevent unauthorized control or configuration changes. Digital display with graphical icons is easy to read and understand.

NOTE: This unit is designed for 4-pipe HVAC systems and not recommended for 2-pipe HVAC systems.

Versatile BACnet Communication in Two Options

  • BACnet MS/TP in B2 models with MS/TP baud rates 9.6kbps – 76.8kbps (BTL Listed)
  • BACnet/IP in BW2 models with 802.11 b/g/n 2.4GHz Wi-Fi
  • Both B2 and BW2 models are BACnet compliant with a B-ASC device profile

Flexible Installation

  • 24VAC (+/-10%) power input
  • Digital Display with graphical icons of operation, °C or °F display
  • Modulating valve control, analog Outputs for Fan Coil Operation
  • Suitable for 4-pipe modulating heat/cool control applications with manual or automatic changeover
    NOTE: 2-pipe heat/cool applications and floating-type valve actuators are not supported by this device
  • Occupied/Unoccupied modes with 2 sets of Cool/Heat set points
  • Effective run time accumulation for energy consumption calculations
  • Built-in temperature sensor
  • Remote temperature sensor input (NTC Thermistor 3kΩ)
  • Occupancy status can be switched (1) locally by the user, (2) by using a separate occupancy sensor, or (3) by using BACnet network command
  • Networked current temperature override from BACnet client (BMS)
  • Fully Configurable Algorithm control parameters: Deadband, Proportional Gain, Integral Rate, Stage Trip Points, Stage Widths, Short Cycle Delay, Maximum Cycles Per Hour
  • Stand-alone operation with setpoints reset and schedule from BACnet BMS or optional full BACnet BMS control
  • Non-volatile memory (EEPROM) retains user settings during power loss
  • Lockable buttons/user interface
  • Operating Environment: 0-50°C, 5-95% RH (non-condensing)
  • Wiring: 14 to 22 AWG wires or 1.5 mm2 wires
  • Dimensions: 94×118×34 mm (W × H × D)
  • Mounts directly onto wall, panel, standard 65×65 mm junction box (hole pitch 60 mm) or standard 2×4 inch vertical junction box (hole pitch 83.5 mm)

Product Details

Note: This unit is designed for 4-pipe HVAC systems and not recommended for 2-pipe HVAC systems.

The BASstat's white backlit LCD display is large and easy to read, even from a distance. It incorporates graphical icons to aid visual indication of current state of operation. Several icons indicate parameters such as: Active Mode, Cooling stage 1 or 2, Heating stage 1 or 2, Ventilation Only, Fan Active, Occupied/Unoccupied state, and Clock icon to indicate Short Cycle Delay or Max Cycles per hour active waiting state. These icons are very useful in indicating the thermostat's current state of operation.

Six buttons on the BASstat allow users to manipulate temperature set point, change HVAC modes, turn the thermostat ON/OFF, and more. Pressing the Set and Up/Down buttons can manually toggle the thermostat from occupied/unoccupied modes, where BACnet occupancy command is not an option. All 6 of these buttons are lockable in a configurable manner to prevent unauthorized configuration change. Some or all buttons can be locked for application flexibility, making the stat suitable for applications where limited user control is allowed.

Sometimes the ideal location to install the thermostat is not the ideal location to capture a correct representation of the temperature in the room, either because it is near a draft, exposed to sunlight, directly under a ceiling fan, near exterior doors or close to equipment that create hot or cold air. In that scenario, a remote temperature sensor is available. Featuring an NTC type 3kΩ thermistor, the temperature sensor is directly compatible with any BASstat model.

Ordering Information

Model Description    
BAST-421C-B2 BACnet MS/TP FCU 4-pipe, single-speed Fan, Wired $155
BAST-421C-BW2 BACnet/IP FCU 4-pipe, single-speed Fan, Wi-Fi $175


Model Description    
TAS-THTRAD0I Room Aero, 3K, with Insulated Pad (Data Sheet) $10

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