Heatrae Sadia Overheating / Thermostat Failure

Water from a Heatrae Sadia cylinder is excessively hot at the taps, even at low draw-off.

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

Stuck immersion thermostat, Faulty cylinder thermostat, Thermostatic mixing valve failed or mis-set, Wiring bypassing thermostat

How to Fix / Troubleshooting

Safety first: High water temperatures can cause severe scalding. Turn off power to the heater immediately and warn occupants.

Steps to correct overheating:

  • 1. Verify thermostat setting: Check immersion and cylinder thermostats are set to around 60°C.
  • 2. Test and reset: Press the manual reset on any overheat cut-outs. If they trip repeatedly, the control thermostat is likely faulty.
  • 3. Inspect wiring: Ensure the immersion is wired through the thermostat and not directly to the supply.
  • 4. Check TMV: If a thermostatic mixing valve is fitted, confirm it is correctly set and functioning. Replace if it does not regulate outlet temperature.
  • 5. Replace faulty thermostat: Fit a genuine Heatrae Sadia thermostat if the existing one does not control temperature correctly.
Advertisements

Repair Difficulty

Medium 3/5

Required Part

Immersion Thermostat / Thermostatic Mixing Valve
Check Price on Amazon

We may earn a commission from links on this page.

Advertisements