ACV Scale Buildup in Heat Exchanger

Water heater emits rumbling or kettling noise during operation

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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

Limescale accumulation on ACV heat exchanger surfaces, High hardness water with no softening, Low flow rates causing localized boiling

How to Fix / Troubleshooting

Safety: Turn off power and allow the unit to cool before descaling. Follow chemical safety instructions.

  • 1. Assess water hardness: If in a hard water area, plan regular descaling or install a water softener.
  • 2. Chemical descaling: Isolate the ACV heat exchanger and connect a descaling pump with appropriate descaling solution. Circulate until noise and scale are reduced, then flush thoroughly with clean water.
  • 3. Flow check: Ensure pumps and valves provide adequate flow through the exchanger to prevent localized boiling.
  • 4. Replace if necessary: If descaling does not restore quiet operation, replace the heat exchanger.

Use only descaling chemicals compatible with ACV stainless steel or copper components as specified by the manufacturer.

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Repair Difficulty

Hard 4/5

Required Part

Primary Heat Exchanger
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