Boiler shows E13 and may shut down during domestic hot water demand
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.
Possible Causes
How to Fix / Troubleshooting
Safety first: Turn off power and close domestic water isolation valves before working on DHW components.
- Step 1 – Locate DHW sensor: On combi Rheem boilers, find the DHW temperature sensor attached to or inserted into the domestic plate heat exchanger.
- Step 2 – Inspect wiring: Check the sensor harness and connector for damage or corrosion. Reseat connectors at both ends.
- Step 3 – Test sensor: With power off, disconnect the sensor and measure resistance. Compare to Rheem’s DHW sensor chart. Replace if readings are incorrect.
- Step 4 – Check for scale: Heavy scale in the plate heat exchanger can cause hot spots and sensor errors. If DHW temperature fluctuates or flow is reduced, a technician should descale or replace the plate heat exchanger.
- Step 5 – Reset and test: After replacing the sensor or cleaning the exchanger, restore power and test DHW operation.
Warning: Domestic hot water circuits are under mains pressure. Always isolate and depressurize before removing sensors or exchangers.
Repair Difficulty
Required Part
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