Chaffoteaux Insufficient Heating / Underfiring

Water heater ignites but hot water temperature is too low even at maximum setting.

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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

Low gas pressure, Partially blocked burner injectors, Scaled primary heat exchanger, Faulty gas valve modulation

How to Fix / Troubleshooting

Safety: Gas pressure and combustion must be checked by a qualified gas engineer.

  • Verify tap flow rate: Excessive flow can reduce outlet temperature. Throttle the hot tap slightly and see if temperature improves.
  • Clean burner and injectors: Remove burner and gently clean ports. Do not use sharp tools on injectors.
  • Descale heat exchanger: Circulate descaling solution through the primary or plate heat exchanger to restore heat transfer.
  • Professional gas check: Have a technician measure inlet and burner pressure and adjust or replace the gas valve if underfiring.
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Repair Difficulty

Hard 4/5

Required Part

Primary Heat Exchanger
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