E20
Triangle Tube Delta-T Too Low / Excessive Flow or Sensor Error

Boiler displays E20: supply/return temperature difference too low.

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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 circulator pump, bypasses or mixing valves wide open, faulty supply or return sensor, control board misreading temperatures.

How to Fix / Troubleshooting

Safety: Turn off the power before adjusting any wiring. Hydronic adjustments should be performed carefully to avoid comfort issues.

  • Step 1 – Check sensors: Confirm the supply and return NTC sensors on the Triangle Tube boiler are firmly attached and wired correctly. Reseat connectors.
  • Step 2 – Review system valves: Look for bypass valves or mixing valves that may be fully open, causing very high flow and a low temperature drop. Adjust according to system design.
  • Step 3 – Pump speed: If the system pump is variable-speed, reduce the speed setting slightly to increase delta-T, following manufacturer guidelines.
  • Step 4 – Reset boiler: Restore power and monitor operation.
  • Professional evaluation: If E20 persists, a technician should verify sensor accuracy and system design flow rates.
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Repair Difficulty

Medium 3/5

Required Part

Supply NTC Temperature Sensor
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