What Temperature Do You Keep a Hot Tub When Not in Use?


The thought of running a hot tub permanently sounds like a huge waste of electricity. The good news is that you can save money by lowering the temperature between uses. So how much should you reduce the temperature?

It’s best to lower your hot tub temperature by 10°F (5°C) overnight when it’s not in use. Lowering the temperature reduces energy consumption, saving you money on your electricity bill. Lowering more than 10°F may not be cost-effective due to the amount of energy required to raise the temperature each time.

In this article, I’m going to show you:

  • When and when not to lower the temperature
  • How much money you can expect to save
  • When it’s okay to turn the power off between uses

Should I lower the temperature of my hot tub when not in use?

Turning the temperature down overnight while the hot tub is not in use is an easy way to save money on your energy bill.

Good hot tubs heat up at a rate of 11°F (6°C) per hour. By lowering the temperature of your spa 10°F (5°C), the water will be back up to your favorite temperature in less than an hour.

So why not lower the temperature even further between uses? After all, the more you lower the temperature, the greater the savings will be, right? Not so fast.

It’s important to strike a balance between financial savings and practicality. If you were to lower the temperature by 20°F (11°C), you would have to wait almost 2 hours each time you fancied a soak.

And the wait would be even longer for those that own an inflatable, plug-and-play, or budget hot tub that has a less powerful heater. We’re talking at least twice as long.

That means having to plan quite a bit in advance each time you want to enjoy your hot tub. I don’t know about you, but that sounds to me like quite a bit of hassle.

By keeping your spa close to optimum temperature, you’ll find yourself using it far more often because of the fact that you can get in on a whim without much planning.

During the winter, it might be worth lowering the temperature by only 5°F (3°C), depending on the quality of your spa’s heater, its insulation, and how harsh the winters are where you live.

The reason being that the cold weather will have a significant impact on heating times, especially if your hot tub isn’t well-insulated.

It’s also better to reduce the temperature by only 5°F (3°C) in an inflatable hot tub when not in use too. This is because the heaters are nowhere near as powerful as those found in hard-shell hot tubs.

Lowering the temperature by more would make it impractical because you’ll end up having to wait several hours each time you want a soak.

So this begs the question: is lowering the temperature actually worth it?

Does turning down your hot tub save a lot of money?

Initially, it seems like a great idea to lower the temperature to save a bit of money on electricity. But is it really worth it? How much can you expect to save?

Turning your hot tub down by 10°F (5°C) results in a saving of $0.41 per 24 hours that the hot tub is not in use. The cost to raise the temperature back up by 10°F is $0.31. If your spa is in daily use, turning it down overnight between uses only saves $0.10 per day.

The average cost per month to run a modern, hard-shell hot tub is $30. Every time you turn the temperature down by 2°F (1°C), you can expect to save 10% on electricity.

We’ve seen that lowering by 10°F (5°C) results in a saving of $0.41 per day ($12.29 per month), but that figure assumes you never use it.

Each time you fancy a soak, you’ll have to heat the water back up. Raising the temperature requires a lot more energy than maintaining it.

The cost to raise the temperature by 10°F (5°C) in a 400-gallon tub is approximately 31 cents. So on the days you reheat the water, the saving becomes just 10 cents.

The answer as to whether or not it’s worth lowering the temperature depends on how much you use your spa.

If you only use it once or twice a week at the most, then I can see it being worth it to lower the temperature each time. On the other hand, if you use your spa 4 or more times per week, then it’s more practical to keep it up to temperature.

You’re not going to save much money turning it down each time, and having it ready to go is so much better if you’re a frequent user.

In terms of practicality, our circumstances are all different. If you’re retired, then hopping out into the yard an hour before you want to get in probably isn’t much hassle.

But if you’re out at work all day, and you really fancy an unplanned soak after a stressful day, then having to wait an hour before you get in could be the difference between bothering and not.

Your hard-shell hot tub has probably set you back at least $5,000. Is saving a few pennies each day worth it if it means you’re not going to make full use of it?

If you only used your hot tub once per week, religiously turning it down by 10°F between uses, the maximum annual savings would be $133.

For the price of one night out a year, only you can decide if it’s worth the effort.

Can you turn off a hot tub when it is not in use?

What about switching the hot tub off between uses if you’re an infrequent user? We’re talking about using the hot tub once or less per week here.

While some argue that you should switch it off between uses, the truth is that you would probably end up spending more on electricity because of having to heat the water from cold each time.

Modern hot tubs are equipped with excellent insulation that makes it far more economical to keep the water heated between uses.

Running a modern hot tub costs around $1 dollar per day in electricity. The cost to heat water from cold in a 400-gallon hot tub is about $6.

Heating the water once per week would result in a saving of $50 or so over the course of a year. But just imagine how impractical it would be having to wait some 9 hours each time while the water heated up.

It would require you having to plan your soak the day before, which just isn’t going to happen if you’re already an infrequent user.

The savings are irrelevant anyway as switching the power to your hot tub off completely between uses would end up damaging it unless you drained the water each time.

Power needs to be left on at all times while water is inside a hot tub in order for it to function properly. The circulator pumps need power to prevent the water from stagnating.

The movement of the water stops you from having to skim off algae each time you get in. The pump ensures that the water flows through the filters, trapping any unwanted debris, and dispersing the chemicals evenly to keep the water sanitized.

Turning the power off during the cold, winter months could cause freezing within the plumbing and motor. Having the pump running ensures that water is constantly moving through the heater so that it never freezes.

Infrequent use and economy mode

If you use your hot tub just a handful of times per month, then it’s well worth lowering the temperature significantly between uses.

Running economy mode lowers the temperature by around 20°F (11°C) and also runs the pump cycles less often, saving you a few hundred dollars each year.

If you’re going to leave your hot tub unattended for more than 2 weeks, then it’s best to drain all of the water.

Draining the water isn’t to save money on unnecessary running costs. The bacteria in a spa can start growing in as little as 2 – 3 days if no chemicals are added to balance the water.

The build-up of bacteria can cause a lot of damage to the hot tub, potentially reducing its lifespan. Unless you have a trusted friend or neighbor that can take care while you’re away, I would advise you to get rid of the water.

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