16
Ruud
Outlet Water Temperature Too High
Ruud tankless water heater displays error code 16; water may be excessively hot before shutdown.
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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
Scale buildup in heat exchanger, Faulty outlet thermistor, Incorrect temperature setting, Low water flow rate
How to Fix / Troubleshooting
Safety first: Turn OFF power and gas. Hot water can cause scalding; use caution when testing.
- Step 1 – Check temperature setting: Verify the set temperature on the control panel is appropriate (typically 120°F/49°C for residential use).
- Step 2 – Ensure adequate flow: Open hot water faucets fully during testing. Very low flow can cause overheating.
- Step 3 – Clean inlet filter and descale: Remove and clean the inlet filter. If scale is suspected, perform a full descaling of the heat exchanger using a pump and descaling solution.
- Step 4 – Inspect outlet thermistor: Check wiring and connector. Replace the outlet thermistor with an OEM Ruud part if damaged or out of spec.
If code 16 persists, a technician should check gas valve modulation and control board operation.
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Repair Difficulty
Medium
3/5
Required Part
Outlet Thermistor
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