Marey tankless heater shuts off when another fixture is opened; water goes cold mid-use.

Safety first: No internal work required initially.

Steps:

• Limit simultaneous use: Avoid running multiple showers or large hot water loads at the same time. Compare your Marey model’s GPM rating to your actual usage.
• Reduce temperature setpoint: Lowering the set temperature reduces required energy and may allow more stable operation under higher flow.
• Check gas/electric supply: Ensure gas line size and regulator match Marey specifications, and that electrical breakers and wiring are sized correctly.
• Clean inlet filter and aerators: Restore proper flow characteristics by cleaning filters and fixtures.

When to call a technician: If the unit shuts off even at low demand, or if gas/electrical supply sizing needs verification.