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NTI · Boiler troubleshooting

Access the low voltage wiring connections

TRX

What is going on

Anytime you wire a room thermostat or chase a low voltage problem on the TRX150, you have to get into the control panel first. What I usually see is people skip the shutoffs because it is only low voltage, but the main board has line voltage on it too, so power comes off first. The panel hinges forward once the screw and tabs are dealt with.

Likely causes

  • Control panel still held by the cross-member screw or the side tabs
  • Power left on while working near the main board
  • Factory jumper on TT1 left in place when a thermostat is wired

Check in this order

  1. Shut off power at the boiler and at the circuit breaker.
  2. Shut off gas at the manual shutoff.
  3. Remove the boiler front cover.
  4. Remove the screw holding the control panel to the cross-member.
  5. Push in the tabs and pull the control panel housing forward.
  6. Disconnect the two clips.
  7. Open the control panel cover to reach the main PCB. If you are wiring a room thermostat, remove the factory jumper from TT1.

Applies to: TRX150

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Source: NTI TRX150 manual, p. 54-55. Written in our own words; check the manual for your exact model.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.