Protherm Electromagnetic Interference (EMI) from Switching Components

Thermostat causes interference with nearby audio equipment or radio when switching.

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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

Inductive load switching without snubber, Poorly routed control cables, Defective relay arcing excessively

How to Fix / Troubleshooting

Safety: Mains voltage may be present on controlled circuits. Isolate power before modifications.

  • Step 1 – Check load type:
    • Identify if the thermostat is directly switching pumps or valves with high inductance.
  • Step 2 – Add snubber (qualified electrician):
    • Install an RC snubber or surge suppressor across the load or relay contacts as per Protherm recommendations.
  • Step 3 – Reroute cables:
    • Separate thermostat control cables from audio or antenna cables.
  • Step 4 – Replace thermostat if relay is arcing:
    • Excessive arcing can indicate a failing relay; replace the Protherm smart thermostat.
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Repair Difficulty

Hard 4/5

Required Part

Protherm Thermostat Relay Output
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