High Limit Operation: Return temp. is higher than supply temp.
1. - Verify boiler and system are full of water.
- Verify system does not have trapped air.
- Inspect and verify system piping and components.
- Verify water flow is not reversed or pipes crossed.
2. Use contact thermometer to check return water temp. Compare to temperature shown with display in “INFO” mode (“2” in first digit). Replace return temp. sensor if results are not close. Replace control module if sensor replacement doesn’t solve problem.
