Boiler makes loud banging or knocking noises when firing or shortly after

Safety first: Turn off power and allow the boiler to cool. Hot water and steam can cause burns.

• Check system pressure: Verify pressure is within Utica's recommended range. Very low pressure can promote boiling.
• Bleed air: Use the boiler's air vent and system vents to remove trapped air, especially near the boiler.
• Verify circulator operation: Ensure the pump is running and sized correctly for the system. A failed or undersized pump can cause kettling.
• Descale if needed: If the system has hard water and the boiler is older, the heat exchanger may need chemical descaling. This should be done by a professional familiar with Utica condensing or cast-iron heat exchangers.