HVACopediaHTP · Boiler troubleshooting
Boiler overheating lockout (F00, F05, F06)
What is going on
Water temperatures running too high and boiler locking out with the pump running.
Likely causes
- Circulator failed or wrong direction
- Closed valves, no water or low flow
- Failed ECO or thermistor
Check in this order
- Check the circulator runs and flows the right way
- Confirm water in system and valves open
- Confirm less than 50 F rise from return to supply in the status menu
- Check thermistor resistance against the chart
- Check ECO wiring; replace ECO if water is not hot
Applies to: EL-80, EL-110, EL-150, EL-220, EL-299, EL-399 (N/LP)
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Source: Elite EL-80 N Installation Manual (LP-293), p. 69, p. 70. 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.