S.53 — Water shortage (VL-RL spread too big), operation blocked

What does S.53 mean?

The boiler has detected a water shortage condition, specifically a large temperature difference between the flow (VL) and return (RL) pipes. This has activated a waiting period, blocking the boiler's operation.

• Too little water in the appliance.
• Blocked pump or defective pump.
• Air in the system.

Click steps to track your progress.

1. 1

   Check the system pressure on your boiler's gauge. If it's low, refill the system to the recommended pressure.

2. 2

   Vent radiators to release any trapped air in the heating system.

3. 3

   If the problem recurs after checking pressure and venting, contact a qualified service technician to inspect the pump and system circulation.