John Wood Thermostat Control Failure (Electric)

John Wood electric water heater has power but no hot water; elements test good

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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

Failed upper thermostat, Failed lower thermostat, Loose thermostat-to-element wiring, Miswired replacement thermostat

How to Fix / Troubleshooting

Safety: Turn off power at the breaker and verify with a meter before touching any wiring.

  • 1. Check voltage: Confirm correct voltage is present at the input terminals of the upper thermostat.
  • 2. Test thermostat continuity: With power off and wires removed, check continuity across the thermostat contacts when calling for heat. Replace any thermostat that does not close properly.
  • 3. Verify wiring: Compare wiring to the John Wood schematic on the access panel. Correct any miswiring from previous repairs.
  • 4. Replace faulty thermostat: Install OEM-compatible thermostats and ensure they are firmly against the tank surface.
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Repair Difficulty

Medium 3/5

Required Part

Upper and Lower Thermostats
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