Viadrus Short Cycling / Control Misconfiguration

Furnace frequently short‑cycles (turns on and off rapidly) without maintaining stable room temperature.

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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.

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Possible Causes

Oversized Viadrus furnace for system load, Thermostat located in poor position, Incorrect control parameters (hysteresis, curve), Pump overrun time too short

How to Fix / Troubleshooting

Safety: Control parameter changes should follow the Viadrus manual to avoid unsafe operation.

  • Thermostat location: Ensure the room thermostat is not near heat sources, drafts, or direct sunlight. Relocate if necessary.
  • Adjust hysteresis: In the control menu, increase the temperature differential (hysteresis) so the furnace runs longer per cycle.
  • Pump overrun: Increase pump overrun time so residual heat is distributed and the furnace does not overheat and shut down prematurely.
  • System design review: If the furnace is significantly oversized, a heating engineer may recommend adding a buffer tank or reconfiguring zones.
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Repair Difficulty

Medium 3/5

Required Part

Room Thermostat
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