Vaillant
Short Cycling / Control Instability
Water heater frequently cycles on and off with short burner run times
Advertisements
Safety Warning
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.
Advertisements
Possible Causes
Oversized appliance for demand, Faulty temperature sensor, Poor water flow modulation, Incorrect minimum burner setting
How to Fix / Troubleshooting
Safety: Isolate power and gas before internal adjustments. Burner settings must be adjusted only by qualified personnel.
- Check flow stability: Ensure a stable and sufficient hot water flow. Very low flow can cause rapid cycling.
- Test NTC sensors: Replace any sensor that shows erratic readings.
- Check modulation (engineer): Verify that the gas valve can modulate down to the correct minimum rate. Adjust or replace as needed.
- Review sizing: If the appliance is significantly oversized for the application, consider hydraulic changes or consult Vaillant for solutions.
Advertisements
Repair Difficulty
Hard
4/5
Advertisements