NTI Boiler: Display shows System Disconnected! constantly
Display shows System Disconnected! constantly on a NTI boiler: Display is powered but cannot talk to the controller.
Applies to: Trinity Tft60, Tft85, Tft110, Tft155, Tft175, Tft200, Tft250, Tft300, Tft399
Common causes of display shows system disconnected! constantly
- Communication wire off
- Blown 24 VAC fuse C
- Failed 24 VAC transformer
- Control board dead
How to fix display shows system disconnected! constantly: step by step
- Check the 4 by 1 Molex connector behind the top of the display is seated
- Check the wires on the back of the display: green to G, white to Y
- Check fuse C
- Look at the power LED on the control and measure 24 VAC at J8 pins 1 and 2; with fuse C good and no 24 VAC, replace the transformer
- If 24 VAC is present, make sure plug J8 is seated, cycle power, and replace the control if it still does not run
If the unit shows an error code, look it up: NTI Boiler codes
Models
Tft60Tft60Tft85Tft85Tft110Tft110Tft154Tft155Tft175Tft200Tft201Tft250Tft285Tft300Tft340Tft399Tft399
Source: NTI Tft60-399 Installation and Operation Instructions (rev. 2012-04-09), Sec. 15.0 Troubleshooting. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.