Water heater appliances and methods of sabbath operation

A water heater appliance comprising

• a casing;
• a tank disposed within the casing, the tank defining an inlet and an outlet;
• an inlet conduit mounted to the tank at the inlet of the tank;
• an electric heating system in thermal communication with the tank to heat water within the tank;
• a mixing valve mounted to the casing downstream from the tank;
• and
• a controller operably coupled to the electric heating system and the mixing valve, the controller being configured to initiate a Sabbath cycle, the Sabbath cycle comprising
• determining an anticipated Sabbath condition at the water heater appliance,
• directing a lower portion of the tank of the water heater appliance to a sub-cooking Sabbath temperature below 45 degrees Celsius based on the anticipated Sabbath condition,
• determining the sub-cooking Sabbath temperature is met at the lower portion of the tank,
• directing a mixing valve of the water heater appliance to a Sabbath set-point temperature in response to determining the sub-cooking Sabbath temperature is met at the lower portion of the tank, and
• directing an upper portion of the tank of the water heater appliance to a stratified Sabbath temperature above the sub-cooking Sabbath temperature.

A method of operating a water heater appliance, the method comprising:

• determining an anticipated Sabbath condition at the water heater appliance;
• directing a lower portion of a tank of the water heater appliance to a sub-cooking Sabbath temperature below 45 degrees Celsius based on the anticipated Sabbath condition;
• determining the sub-cooking Sabbath temperature is met at the lower portion of the tank;
• directing a mixing valve of the water heater appliance to a Sabbath set-point temperature in response to determining the sub-cooking Sabbath temperature is met at the lower portion of the tank;
• and
• directing the mixing valve to a fully open position based on the anticipated Sabbath condition prior to determining the sub-cooking Sabbath temperature is met at the lower portion of the tank.