HVACopediaNTI · Boiler
Hold / Lockout 85 Inlet/outlet inversion limit
What the control is telling you
Inlet water reads hotter than outlet, which means water is going through the boiler backwards (or the sensors are swapped).
Applies to: Trinity Tft60, Tft85, Tft110, Tft154, Tft201, Tft285, Tft340, Tft399
Likely causes
- Pump pushing water through the boiler in the wrong direction
- Factory sensor wiring wrong
Test and repair steps
- Make sure circulation runs in the direction shown in the piping drawings
- Unplug the flue sensor cable the display should show Hold 95 - if it does not, contact NTI
Models that show this code
13 models in Trinity Tft
Other codes on the same units
- Hold / Lockout 79 Outlet high limit
- Hold / Lockout 81 Delta T limit
- Hold / Lockout 81 Delta T limit
- Hold / Lockout 85 Inlet/outlet inversion limit
- Hold / Lockout 88 Outlet temperature rise limit
- Hold / Lockout 88 Outlet temperature rise limit
- Hold / Lockout 9 Flame bias out of range
- Hold / Lockout 9 Flame bias out of range
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Source: NTI Trinity Tft399 Installation and Operation Manual (2018-09-07), Sec. 16.0 Troubleshooting, Table 16-3. Summarized in our own words; check the original manual for your model.
Homeowner looking at this code? See what it means for you and when to call a technician.
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.