Unlike an in-ground spa, Caldera hot tubs are designed to be hot and ready for use at all times. Caldera hot tubs are highly energy efficient and feature hot tub insulation and hot tub covers with the highest possible efficiency to ensure the lowest possible energy costs.
If you just filled your hot tub with fresh water, it will take several hours to heat up initially, depending on how many gallons of water need to be heated. Check the Owners Manual for your specific hot tub model to find out how long it should take to get up to temperature after a water change.