H7
Buderus
DHW Flow Rate Too Low / DHW Sensor or Flow Fault
Boiler shows H7; DHW performance reduced or intermittent
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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
Partially blocked DHW plate heat exchanger, Scaled DHW flow sensor, Low mains water pressure, Faulty DHW NTC sensor
How to Fix / Troubleshooting
Safety: Isolate power and water before removing DHW components. Risk of scalding.
- 1. Check mains pressure: Ensure cold water pressure to the boiler is adequate and that inlet valves are fully open.
- 2. Clean inlet filter: Remove and clean the cold water inlet filter on the Buderus combi boiler.
- 3. Descale plate heat exchanger: If DHW temperature fluctuates or is low, the plate heat exchanger may be scaled. A technician can remove and chemically descale or replace it.
- 4. DHW sensor and flow sensor: Inspect and test the DHW NTC and flow sensor; replace if faulty.
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Repair Difficulty
Hard
4/5
Required Part
DHW Plate Heat Exchanger / DHW Flow Sensor
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