Rinnai Internal Water Leak

Boiler leaks water from the bottom or from internal components; puddles may form under the unit.

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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

Corroded primary heat exchanger, Leaking pump seals, Loose compression fittings, Cracked plastic manifolds or hoses

How to Fix / Troubleshooting

Safety first: Turn off power and isolate water supply to the boiler. Water may be hot.

  • Identify leak source: Remove the front cover and carefully inspect for dripping or staining. Use a flashlight and mirror if needed.
  • Tighten fittings: Gently tighten accessible compression or union fittings that are visibly leaking. Do not overtighten plastic components.
  • Check condensate vs. system water: Determine if the leak is clear condensate (from the condensate trap) or system water (often discolored). This helps identify the source.
  • Professional repair: Leaking heat exchangers, pumps, or manifolds typically require component replacement by a technician.
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Repair Difficulty

Hard 4/5

Required Part

Primary Heat Exchanger
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