HVACopediaNTI · Boiler troubleshooting
Stack limit lockout (Lockout 82)
What is going on
Flue temperature went past the stack limit.
Likely causes
- Dirty combustion chamber or heat exchanger
- Stack limit set wrong
- Bad stack sensor
Check in this order
- Clean the combustion chamber and heat exchanger
- Set the stack limit to 220 F (104 C) maximum, or 149 F (65 C) for PVC exhaust in Canada
- Compare sensor resistance with the thermistor chart
Applies to: Trinity Tft60, Tft85, Tft110, Tft155, Tft175, Tft200, Tft250, Tft300, Tft399
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Source: NTI Tft60-399 Installation and Operation Instructions (rev. 2012-04-09), Sec. 15.0 Troubleshooting. 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.