High Limit Operation: Burner off until outlet water temperature drops below 180°F
1. Happen when heat demand is lower than lowest firing rate of boiler, such as operation of single, small zone. Check system for:
- Verify boiler and system are full of water.
- Verify system does not have trapped air.
- Inspect and verify system piping and components.
- Verify piping agrees with boiler manual recommendations.
2. Use contact thermometer to check outlet water temp. Compare to temperature shown with display in “INFO” mode (“1” in first digit). Replace return temperature sensor if results are not close. Replace control module if sensor replacement doesn’t solve problem.
