Bosch Localized Overheating at Thermostat

Thermostat backplate or surrounding wall feels unusually warm to the touch.

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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

Thermostat mounted above warm pipe or flue in wall, Excessive current through internal relays due to miswiring, Poor contact causing resistive heating at terminals, Internal component fault

How to Fix / Troubleshooting

Safety: Turn off power to the HVAC system at the breaker before removing the thermostat.

  • Remove thermostat: Gently pull the thermostat off its wall plate and inspect for discoloration, melting, or burnt smell.
  • Check wiring: Ensure only low‑voltage control wires are connected; never connect 120/230 V mains to the thermostat. Tighten any loose terminal screws.
  • Inspect wall cavity: Feel inside the wall opening (carefully) for hot pipes or flues that may be heating the area. If present, relocate the thermostat.
  • Do not ignore burning smell: If you detect burning or see damage, leave power off and contact a professional immediately.
  • Replace thermostat if damaged: Any signs of heat damage warrant replacement of the thermostat.
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Repair Difficulty

Hard 4/5

Required Part

Bosch Smart Thermostat Main Control Assembly
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