Most people like to keep their hot tub temperature at 102-104 degrees, especially in the winter. We generally don’t recommend setting the temperature below 90 degrees.
It is best to keep your hot tub at the same temperature all the time, if you’re going to use it regularly. If you like using it at 102, keep it at 102 between usages. If you like it at 104, keep it between usages at that 104 temperature.
If you’re not going to use your hot tub for a couple of weeks and you think you’re going to save money by turning it down, you can turn it down. Keep in mind, turning down the temperature is not likely to change your electric bill by much.
The concern with setting the temperature too low is that in the case of power failure it significantly reduces the time you have to solve the problem. At 102-104 degrees a Royal Spa hot tub has at least 7 days before freezing risk sets in.
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