Furnace shows A16, unit does not start, may be associated with low system water pressure on hydronic models

Safety: Turn off power. Allow the system to cool before adding water.

• Check system pressure: Read the pressure gauge on the Beretta furnace. If below the recommended value (often around 1.0–1.5 bar when cold), slowly open the filling loop valve and add water until the correct pressure is reached. Close the valve tightly.
• Bleed air: Bleed radiators or air vents to remove trapped air, then recheck pressure and top up if needed.
• Inspect for leaks: Look for visible water leaks around the furnace, radiators, and piping. Repair leaks before repeatedly topping up.

If pressure is correct but A16 remains, the water pressure switch or sensor may be faulty and should be replaced.