Rheem
No DHW Flow Detection
Boiler display shows normal operation but there is no domestic hot water flow when a tap is opened (combi models)
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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
Stuck DHW flow sensor or turbine, Blocked inlet filter on cold water supply, Closed isolation valve on DHW inlet, Faulty diverter valve not switching to DHW
How to Fix / Troubleshooting
Safety first: Turn off power and close domestic water isolation valves before removing filters or sensors.
- Step 1 – Check valves: Ensure the cold water inlet and hot water outlet isolation valves at the Rheem combi boiler are fully open.
- Step 2 – Clean inlet filter: Remove and clean the cold water inlet filter screen. Debris here can completely block DHW flow.
- Step 3 – Inspect DHW flow sensor: Remove and clean the DHW flow sensor or turbine. Ensure it spins or moves freely.
- Step 4 – Diverter valve: If the boiler heats the heating circuit but not DHW, the diverter valve may not be switching. Inspect and repair as described in the diverter valve fault section.
Warning: Do not run the boiler dry on the DHW side; always ensure water is present before testing.
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Repair Difficulty
Medium
3/5
Required Part
Cold Water Inlet Filter
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