Issues with TAC Xenta 100 controller V outputs


The actuators or devices terminated off of the V outputs are not working properly.

Product Line

TAC Vista


  • ZBuilder
  • 121 FC/HP controllers


The triac outputs on the TAC Xenta 100-series controllers are sinking (switching the ground connection) rather then voltage sourcing (switching the hot connection) except for the Xenta 104-A.


Since most equipment requires voltage sourcing then there are two possible solutions:

  1. For the TAC Xenta 121, use the Zbuilder to reassign the I/O to use a relay output (max 4). This is sufficient for basic applications such as cooling, heating, and fan on a Fan Coil Unit or reversing valve, compressor, fan, and strip heat on a Heat Pump.
  2. Install interposing relays on the triac outputs.