Reliance tankless or hybrid water heater shows E1 and shuts down, no hot water

Safety first: Turn OFF power at the breaker and close the cold water supply valve to the heater. Allow hot water lines to cool before disassembly.

Steps to check:

• 1. Verify water supply: Ensure the main cold water shutoff to the heater is fully open. Check that any isolation valves on a tankless manifold are fully open.
• 2. Clean inlet filter: Locate the cold water inlet filter screen (usually at the cold inlet connection). Shut off water, relieve pressure by opening a hot tap, then remove and clean the screen with a soft brush under running water. Reinstall and restore water.
• 3. Check for low flow: Open multiple hot water taps and observe if flow is weak. If house-wide, there may be a plumbing restriction upstream of the heater.
• 4. Descale heat exchanger (tankless/hybrid): If the unit is older or in a hard-water area, scale may restrict flow. Follow Reliance’s descaling procedure using a pump, hoses, and descaling solution connected to the service valves.
• 5. Test/replace flow sensor: With power OFF, locate the flow sensor on the cold inlet manifold. Inspect wiring and connector. If wiring is intact and E1 persists after cleaning and descaling, replace the flow sensor with the correct Reliance part.

Note: Never run the unit without the inlet filter installed. Always restore power only after all covers are reinstalled.