Boiler displays F41, burner output limited, poor heating performance

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Insufficient circulation, pump speed too low, blocked heat exchanger, closed valves, undersized system volume

Safety: Avoid repeatedly resetting the boiler without addressing circulation issues.

Open all circuits: Ensure all heating zones and valves are open when testing.
Increase pump speed: If adjustable, set the pump to a higher speed as per Viessmann instructions.
System balancing: Check that bypass valves are correctly set to allow minimum flow.
Technician tasks: Clean strainers, check for sludge, and verify correct hydraulic design. In some cases, adding a low-loss header or buffer may be required.

Hard 4/5

Circulation Pump

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