Atlantic water heater heats water but temperature is too low compared to thermostat setting.

Safety: Isolate electrical power before removing covers.

• Verify the thermostat setting and ensure the knob has not been accidentally turned down.
• Measure actual hot water temperature at a tap after a full heating cycle; compare with the setpoint.
• On dual-element Atlantic models, test each element's resistance individually; replace any open element.
• Inspect the element for heavy limescale; if present, drain the tank and descale or replace the Atlantic heating element.
• If elements are good and scaling is moderate, replace the thermostat cartridge or electronic sensor assembly to restore accurate temperature control.