Platform & Control Notes
Trinity Tft/TFTN (Honeywell SOLA) show bare numeric codes (e.g. 110). Trinity Tx/FTV (Argus display) show 'Loc' lockout and 'Err' blocking codes. Numbering does NOT map across the two — identify yours by whether the display shows a bare number or a 'Loc'/'Err' prefix.
Model Families & Platforms
- Trinity Tft & TFTN (Honeywell SOLA control platform)
- Trinity Tx & FTV (Argus control display platform)
Diagnostic Characteristics & Common Service Topics
NTI boilers utilize specific display codes and safety lockouts to protect the heat exchanger, combustion system, and hydronic loop. Everyday issues like pressure loss, flame sensing errors, or circulator faults trigger specific responses depending on the controller generation.
| Code | Meaning | Action Required |
|---|---|---|
| 110 (Tft) | Ignition failure — tried the max times and couldn't light or hold flame, so it locked out. | Confirm gas is on and the thermostat is calling, then press Reset once. If it locks out again, stop and call a licensed technician. Never repeatedly reset a boiler that won't light. |
| 67 (Tft — ILK OFF) | Safety interlock open — a device in the interlock loop (low-water cutoff, external high-limit, blocked-vent/air switch) tripped or lost continuity. | Check that system pressure is ~12–25 psi. Beyond confirming pressure, an open safety interlock should be diagnosed by a tech. Do not bypass. |
| 79 (Tft — outlet high limit) | Supply water temperature exceeded the high-limit setpoint. | Make sure valves are open and the circulator runs; bleed obvious air if you know how. If it keeps tripping, call a pro. |
| 81 (Tft — Delta-T limit) | Temperature difference between supply and return is too large — inadequate flow. | Confirm the circulator runs and valves are open. Persistent delta-T limits are a flow problem — have a tech verify pump sizing and purge air. |
| 91 / 92 / 93 (Tft — sensors) | Temperature sensor fault: 91 return, 92 supply, 93 domestic hot water. Out-of-range reading. | No homeowner action beyond one reset. A failed sensor needs a tech to test and replace the specific probe. |
| 100 (Tft — pressure sensor) | Control sees an invalid reading from the water-pressure sensor. | Check the gauge — if under ~12 psi the system may need topping up by someone familiar with the fill valve. If pressure is normal, the sensor is suspect; call a pro. |
| Loc 1 (Tx) | Ignition error — repeated unsuccessful ignition attempts; locked out. | Confirm gas is on and press Reset once. If it locks out again, stop and call a technician. |
| Loc 5 (Tx — limit/safety) | A safety-limit device opened: external limit/low-water cutoff OR the internal heat-exchanger thermal fuse opened from overheating. | You may check system pressure, but an open limit/thermal fuse must be investigated by a technician. Do not bypass. |
Complete Error Code Library
For the complete searchable error-code lookup table for NTI equipment (including all 11 codes, exact lockout causes, and technician actions), visit the Phillips Hydronics Error Code Library.
Related Symptom & Diagnostic Guides
Sources & Documentation
- error-codes.json — https://www.manualslib.com/manual/846337/Nti-Tft60-399.html?page=70