Viessmann Short cycling / control or sizing issue

Furnace short cycles (frequent on/off) without maintaining stable temperature

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

Boiler oversized for load, Incorrect minimum output settings, Faulty room thermostat placement, Low system water volume

Safety: Short cycling reduces efficiency and can damage components over time.

Check thermostat location: Ensure the room thermostat is not near heat sources, drafts, or in direct sunlight.
Increase hysteresis: If possible, adjust the thermostat differential or cycle rate to reduce rapid cycling.
Open more emitters: Ensure enough radiators or zones are open when the boiler runs to provide adequate load.
Professional adjustment: A technician can adjust minimum burner output, add a buffer tank, or reconfigure controls to reduce cycling.

Medium 3/5

Room Thermostat / Control System

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