Reliance tankless water heater displays E7 and will not ignite.

Safety first: Turn OFF the gas at the shutoff valve and disconnect power. Allow the unit to cool. Work in a well-ventilated area and avoid open flames.

Steps to check:

• 1. Verify gas supply: Ensure the gas shutoff valve to the heater is fully open. Confirm that other gas appliances in the home operate normally.
• 2. Inspect igniter and flame sensor: Remove the burner access cover. Locate the igniter and flame sensor rods. Clean them gently with fine emery cloth or a Scotch-Brite pad to remove oxidation. Do not bend or crack the ceramic insulators.
• 3. Check wiring: Inspect the igniter and flame sensor wires for cracks, burns, or loose connections at the control board. Reseat the connectors.
• 4. Examine burner: Look for debris, rust flakes, or spider webs in the burner and orifices. Clean with compressed air or a soft brush. Do not enlarge the orifices.
• 5. Test ignition: Restore gas and power, then attempt to start the unit while observing through the sight glass. If there is no spark or flame, the igniter or gas valve may be faulty and require replacement.

Warning: If you smell gas continuously or see signs of flame rollout, shut off the gas immediately and contact a professional.