Heater shuts down with E04 after running briefly; may be hot to the touch

Safety: Turn off power and allow the heater to cool completely before touching internal components. Do not bypass safety switches.

• Verify water flow: Ensure the pump is running at full speed and that the filter is clean. Check for closed valves or partially blocked lines to the heater.
• Bleed air from system: If your Sta-Rite heater or plumbing has air relief valves, open them briefly to purge trapped air that can cause hot spots.
• Inspect high limit switches: Locate the high limit switches on the water manifold. Check wiring for loose or corroded connections. With power off and heater cool, test each high limit switch for continuity. An open switch at normal temperature indicates failure.
• Check for scale buildup: If the heater is older or used with hard water, the copper or cupronickel heat exchanger may be scaled internally, restricting flow and causing overheating. Look for signs of reduced flow and elevated outlet temperature. Chemical descaling or heat exchanger replacement may be required.
• Replace faulty high limit: If a high limit switch fails continuity testing at room temperature, replace the Sta-Rite high limit switch with an OEM-rated part.