Marey heater displays normal operation but hot water output is lukewarm or not hot enough.

Safety first: No immediate internal work required.

Steps:

• Reduce flow: Partially close the hot outlet isolation valve or use a lower-flow showerhead to reduce GPM and increase temperature rise.
• Increase set temperature: Raise the setpoint within safe limits (not above ~125°F / 52°C for general use).
• Check gas pressure and supply: For gas models, ensure the gas line and regulator meet Marey specs; low pressure requires a gas technician.
• Check elements (electric): If electric, one element may be out. Have a technician test and replace any failed elements.

When to call a technician: If the unit cannot achieve expected temperature rise even at low flow and proper supply conditions.