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  • Writer's pictureAqua Warehouse

How Long Does a Hot Tub Take To Heat Up?

Updated: Jan 4, 2023

Most people who try hot tubs for the first time want to know how long it will take to heat up a hot tub. How long it takes to heat up depends on a number of factors. These include whether you cover the hot tub, the water heater rating, and the ambient temperature.

Hot tubs are a great addition to any house and can be ideal for relaxing after a long day with a therapeutic soak. Many hot tub owners wonder how long it takes for their tub to heat up, while others are puzzled about why it takes so long.

In this article, we will be looking at the time it takes to heat up a hot tub depending on these factors, what you should expect, and how to improve the heating process.

How Long Does It Take To Heat Hot Tub Water?

Most people ask, "how long does it take a hot tub to heat?" That information depends on a lot of things. Water is a liquid, and liquids happen to heat quicker than solids, but they still require some time to heat.

If this is the first time you are heating your hot tub, the time it takes to heat the hot tub's water depends on your tub's water heater. If you have a powerful heater, it will take less time for the hot tub's water to go from cold water to the ideal temperature.

Typically, water heats up by five to ten degrees Fahrenheit in an hour. Heating your hot tub to the desired temperature in the 100 to 102 degrees Fahrenheit range can take three to eight hours.

Why Does A Hot Tub Take So Long To Heat Up?

The overall condition of your hot tub and its components, such as the cover, jets, pump, and water heater, affect how fast the cold water reaches the desired temperature. The hot tub's components should be maintained in optimal condition to allow heat and water to flow freely.

If you place your hot tub outside, the ambient air temperature also affects the heating process. The warmer the temperature outside, the faster your hot tub heats up.

What Are The Factors That Affect How Long A Hot Tub Takes To Heat?

Most hot tubs can hold up to 320 gallons of water, which could be a lot to heat up when you are ready for a relaxing soak. Here are the factors which determine how long it takes to heat up your hot tub.

Base (Starting) Water Temperature

The initial water temperature is an obvious factor, but it still has to be mentioned. The starting temperature of your hot tub impacts how quickly your hot tub heats the water in it. Leaving your hot tub running all the time also affects the time it takes to heat up, making it a shorter process.

Ambient (Surrounding) Temperature

Ambient temperature is the measure of how cold or warm the air is surrounding your hot tub. The heating time for your hot tub will be longer if it's outside in the cold air rather than inside in a warmer environment.

If your hot tub is in a windy spot, you can control the air temperature around it and reduce the time it takes for your hot tub to heat by taking the following steps:

  • Plant two rows of shrubs as a natural wind barrier

  • Set up a windscreen for the hot tub to block the prevailing wind.

You can also choose to position your hot tub in a naturally sunny spot to take full advantage of the sun's warmth to heat the water.

Tub Insulation

It is important to remember that good insulation makes it faster to heat a hot tub, as it will retain heat inside better. Heat can escape from the surface of the heated water and into the air. It can also dissipate through the hot tub cabinet seams or if there are tiny cracks.

The hot tub's base is another area that could cause the heated water to lose its heat energy. Your hot tub will heat slower if on a concrete pad or similar base. You should identify all the sources that may reduce the heat inside the hot tub and insulate accordingly.

Hot Tub Size

Typically, it will take more time to heat a big hot tub. And less time to heat a small hot tub. Of course, if you own a large tub with a 1-kilowatt heating element, it could take a lot of time waiting to heat up your hot tub.

Ensure that you do not purchase a tub that is way too big for you. You will be unnecessarily heating a lot of water if you have a six-seater hot tub and it's only two people in it most of the time. Excessive heating will increase hot tub running costs and overall energy consumption and has an adverse environmental impact.

A well-designed tub should have a heating element that matches its water capacity. But check to find out the heating element capacity of any hot tub you consider buying.

Heater Efficiency And Power

Another thing that affects the time needed to heat up a hot tub is the efficiency and power of the heater. The power ratings are in kilowatts, and ideally, the higher the rating, the faster it heats up the water.

In theory, this means that a 4-kilowatt heating element will heat water two times faster than a 2-kilowatt heating element. There is the matter of it consuming more electricity in a shorter time. But there is also less heat loss to the air and surroundings as the water is heated faster.

Does A Hot Tub Heat Faster With the Jets On Or Off?

There is a bit of controversy regarding whether leaving the jets on or off affects the water temperature. A compromise is to run the jets periodically while heating or turn them on as the water gets closer to the ideal temperature. Doing so ensures that the warm water is already in circulation before you get in. Switching the jets on is advisable because they break up any cold pockets in the pipes.

How Can You Heat Your Hot Tub Faster?

It can be hard to know how long it will take to heat a hot tub as many factors are involved. However, you can improve heating efficiency by doing some simple things. Keep the filter clean, find the best location for your hot tub, and use a top-quality cover to prevent heat loss.

Use Hot Tub Cover

Hot air rises from hot tubs. So hot tub covers as the first line of defence when it comes to retaining heat and warming the water as quickly as possible. You might be wondering why you need a tub cover.

A thermally efficient cover helps the water become hotter faster and reach the desired water temperature. Using a hot tub cover will save energy and money.

Check for a sign of cracks or holes in your hot tub cover. If so, replacing it is the best option. You should not continue using an old hot tub cover if it has impaired efficiency.

There are plenty of cover options to select from for most models of hot tubs, even one that surrounds the entire hot tub. These models are ideal for winter use, but there is no harm in using them all the time to prevent any thermal loss.

Consider Floating Thermal Blanket

A thermal spa blanket is an insulated sheet designed to float on the surface. It looks like a sheet of bubble wrap.

It will trap heat inside the cabinet and water, particularly during winter. You can provide an extra layer of protection for your hot tub by using a thermal blanket underneath the cover to prevent heat from escaping from the surface.

For people looking to add more insulation than provided by a cover, a thermal blanket is a perfect solution. These thermal blankets come in different sizes, so you might have to trim them to fit your spa correctly.

Routine Maintenance & Servicing

If planning to enjoy a fun time in your hot tub at home, you should bear in mind that you have to keep it in perfect working condition by regularly maintaining and servicing it. If you notice or realize that any part of your hot tub needs attention, fix it immediately. Hot tubs in optimal condition help save on energy costs.

Maintenance is not a thing to enjoy, but it could make a difference in how the hot tub's heating system works. You can ruin the materials and elements of your tub if you don't take care of them properly.

Help your spa run efficiently, circulate water better, and finally, reduce the time it takes to heat up by:

  • Making sure the jets operate as they should

  • Regularly maintaining the pump

  • Cleaning the filters and replacing them when necessary

Use Standby And Sleep Modes

If you want your hot tub to heat faster, do not turn it off. Instead, use the sleep mode if you don't plan to use your spa for some days, as it is a great way to conserve energy and keep it ready to use.

Your hot tub will heat faster when it comes out of sleep mode as it is already at a warm temperature. The sleep mode is a beneficial feature for those looking to save money while keeping the tub well poised for use.

Portable Immersion Heater

Assuming your hot tub is very slow to heat the water, and you cannot figure out what else to do to speed up the process, try using a portable immersion heater. It's a small electric device that you place in the water. We live in a constantly evolving world, so you must move with the times.

By mixing the features of the immersion heater with the regular heating capacity of your hot tub, you can significantly reduce the time it takes to get your water to the desired temperature level.

When looking for a portable immersion heater, it is advisable to shop for one with at least 1500 watts as it will provide you with the best effect.

Is It Safe To Fill A Hot Tub With Hot Water And Heat It?

While you could lose patience filling your new hot tub with water from the garden hose while you wait hours for it to heat up, avoid using hot water to try and speed up the process. You might end up damaging the tub's shell as most hot water heaters exceed the heat rating for a hot tub. And it will be laborious to heat water on your stove-top, and it will take you a bit longer than you imagined.

Water that is above 104 degrees could damage your spa. Hot tubs are not designed to withstand scalding temperatures, meaning that they could begin to give way or melt.

While you might speed up the process slightly, it is not worth the risk as you could damage your spa. So, it's best to follow the above steps and wait for the water to reach the right temperature the correct way.


Most hot tub owners will do anything to reduce the time it takes for their hot tub to heat. Luckily, there are plenty of ways to shorten the time needed for your to get hot, like getting a new heater or planting shrubs.

To ensure that your hot tub heats up as efficiently as possible, you will need to pay attention to a few key things.

First, make sure your hot tub is properly insulated and sealed. This will help keep heat from escaping, allowing it to be stored in the water for a longer time. Additionally, you should take care to minimize how much condensation builds up on the inside of your enclosure. Excess humidity can reduce the effectiveness of your heating element by causing it to overheat, leading to inefficiencies and increased energy consumption.

Finally, you may want to consider investing in a high-quality filtration system. This will help maintain the water quality and keep chemicals at healthy levels, allowing for more efficient heating. With these tips in mind, you can rest assured that your hot tub will heat up efficiently every time!

You can choose any way to tackle the problem of prolonged heating time. What doesn't change is the fact that an average-sized hot tub will take about three to four hours to reach the ideal temperature. But, following the above recommendations can buy you some time and allow you to begin soaking quicker.




Jess Court

I'm Aqua Warehouse Groups Marketing Officer - overseeing all things news worthy in the hot tub industry, with tips and tricks that are bound to make a splash.

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