Ravenheat DHW Modulation / Flow Instability

Furnace starts and stops repeatedly when hot water tap is partially open, causing temperature fluctuations.

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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

Minimum flow rate not achieved, Partially blocked inlet filter, Faulty DHW flow sensor, Incorrect gas modulation settings

How to Fix / Troubleshooting

Safety: Water temperature may fluctuate; risk of scalding. Use caution at taps and showers.

User checks:

  • Open the hot tap fully to see if operation stabilises.
  • Clean tap aerators and shower heads to improve flow.

Technician checks:

  • Clean or replace cold inlet filter on the appliance.
  • Test DHW flow sensor and replace if readings are unstable.
  • Check gas valve modulation and minimum rate settings.
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Repair Difficulty

Medium 3/5

Required Part

DHW Flow Sensor
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