Attack
DHW Production Failure
Radiators get hot but domestic hot water from taps is cold or only lukewarm on a combi boiler.
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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
Faulty DHW flow sensor on Attack combi boiler, Blocked plate heat exchanger due to limescale, Stuck diverter valve not moving to DHW position, Incorrect DHW temperature setting on control panel
How to Fix / Troubleshooting
Safety: Close cold water inlet and isolate power before opening DHW components.
Steps:
- Check settings: Ensure DHW mode is enabled and temperature is set high enough on the Attack control panel.
- Observe boiler during DHW draw: Open a hot tap fully and watch the boiler. The burner should ignite and the display should show DHW operation. If not, the flow sensor or diverter valve may be faulty.
- Clean inlet filter: Remove and clean the cold water inlet filter to ensure adequate flow through the plate heat exchanger.
- Descale plate heat exchanger: In hard water areas, have a technician chemically descale or replace the DHW plate heat exchanger.
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Repair Difficulty
Medium
3/5
Required Part
DHW Plate Heat Exchanger
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