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How long does a hot tub take to heat up?

August 17, 2023

Estimated read time - 5 minutes

Author - Fin Green - Content Writer UK - Jacuzzi Group

How long will my hot tub take to heat up? Why does my hot tub take so long to heat up? How can I heat my hot tub up quicker? 

All of these are valid questions to ask whether you are planning to buy a hot tub, already own one, or just want more information on hot tub heat times overall. 

This article will discuss all these questions and include facts, statistics, advice and everything in between.

At the end of this read, you should have ample knowledge of, figuring out your own tubs heat up time, tips to help your hot tub heat up faster and much more. 

Jacuzzi® Hot Tub dials lit up at night

How quickly can I use my hot tub after it is delivered?  

It is generally recommended to wait at least 24 hours after your hot tub is delivered before using it. This waiting period is not primarily related to the temperature of the water, but rather to allow the chemicals to balance and initial shock sanitiser levels to reduce to a usable amount.

This ensures a safe and balanced water environment for your enjoyment. 

In this article, we will be putting chemicals aside, and only focusing on the time it takes for the water to reach a sufficient temperature.

The specific waiting time required in terms of temperature, may depend on the type of water treatment products used, the size of the hot tub and many more factors, which we will discuss in the below sections. 

What factors affect how quickly a hot tub heats up? 

It is difficult to say a set amount of time it would take for your hot tub to heat up, as each and every hot tub will have a different time frame, due to many variables:


Temperature of the water going into the hot tub 

The initial temperature of the water going into your hot tub will affect its heat up time. Usually, this is about 12 degrees Celsius out of an outdoor cold water tap in a garden, the warmer the water is, the less time it will take to heat up to your optimal temperature. 


In warmer climates you'll find that greater sun and air heat can lead to water temperature rising faster.



Greater insulation will lead to faster heating as the energy will be better retained in the spa pool. A hot tub retains heat through multiple layers of insulation from the base, through to internal foam and the cover. You can take a look at the best insulation types for your hot tub here. 

Heat source 

The type of heat source you own for your hot tub can determine how long your hot tub takes to heat up. Some options could be an electrical heater, air source heat pump and/or ground source heating.

The best type for you will depend on your specific needs and preferences, which you can ask your dealer about. 


Size of heat source 

The heating output of your heat source will dictate how powerful it is and therefore how quickly it can heat the water in your hot tub. 


Water volume 

Larger tubs will a higher water volume will naturally take longer to heat. A swim spa will take a lot longer than a hot tub for example. 


Desired water temperature 

Everyone has a preferred water temperatures however, the most common temperature range is usually 36-38 degrees Celsius. Read this article to learn more about why hot tub temperature matters, common questions and more.

Maintenance and efficiency 

Regular maintenance of your hot tub, including cleaning the filters and descaling your heater can contribute to more efficient heating.

If the filters are clogged, this can reduce circulation efficiency, which can slow the heating process. Similarly, if your heater has a build up of scale on it then it can be less effective in heating the water. 


How long does it take to heat up a Jacuzzi® hot tub - the facts 

Now lets get down to the numbers of how long a hot tub takes to heat up.

Based on Jacuzzi® products’ design and insulation, the figures show three examples of Jacuzzi® Hot Tub heat up times. Please note, this is only for Jacuzzi® Hot Tubs, other brands may vary. It's also worth noting that the factors discussed above can impact heat up time, even if you have the same model listed below. 

  • For a Jacuzzi® J-315™, with an average water volume of 795 litres and a 2.7kW heater, the hot tub will on average heat up 3 degrees every hour for around 8 hours to heat to 36 degrees Celsius. 

  • For a Jacuzzi® J-335™, with an average water volume of 1,325 litres and a 2.7kW heater, the hot tub will on average heat up 1.7 degrees every hour for around 14 hours to heat to 36 degrees Celsius. 

  • For a Jacuzzi® J-475™, with an average water volume of 1,667 litres and a 2.7kW heater, the hot tub will on average heat up 1.4 degrees every hour for around 17 hours to heat to 36 degrees Celsius. 

Using these three examples, the average Jacuzzi® hot tub heating time with a 2.7kW heater will take around 13 hours. 

How can outside temperature affect hot tub heating time? 

We tested a J-335™ with the above factors (volume of 1,325 litres and a 2.7kW heater) in two different temperatures: 

  • UK average heating as per above is 14 hours 
  • We tested the same model at –5 degrees overnight and it increased heat up duration to 20 hours 

Result: Drastic outdoor temperature difference affected heat up time by 6 hours. 

Jacuzzi® Hot Tub in summer flowers

Why does my hot tub take so long to heat up? 

This is a very common and valid question for a hot tub owner to ask. The factors in the section above should hopefully have at least one answer for your queries.


If you are already a hot tub owner and have never had this issue before, it may be worth checking on your insulation, filters, heater, or water circulation to see if there is any problems. 

If you can't pinpoint what could be wrong, it may be worth contacting your dealer to either get some advice on your specific hot tub, or for an engineer to come and check themselves and diagnose any issues. 

How can I heat my hot tub up quicker? 

Other considerations on how you can speed up your hot tubs heating time: 

  • Leave the cover on the spa to avoid unnecessary heat loss and avoid use until the spa is at temperature 
  • Increase the temperature of the water entering the spa as its filling up 
  • For commercial products, customers can add heater upgrades to increase power up to 6kw which can more than halve the heat up time 
  • If you have the Smart Tub® app, you can use the Smart Heat Mode feature to schedule when you want to use your hot tub. It acts like a programmable time for heating your home. The hot tub will program itself to heat the water to the temperature you want, when you want. To learn more about SmartTub® and Smart Heat Mode, read this article.

How soon can I use my hot tub after drain and refill? 

Once your water is chemically balanced and initial sanitiser shock levels reduced to a usable level, you can use your hot tub as soon as it has reached a comfortable temperature for your personal preference. This heat up time will depend on the above factors. 

How soon can a holiday home hot tub be used after drain and refill? 

Holiday home hot tubs should not be used by clients until they reach the desired temperature of the owners standard. This is usually around 36-38 degrees Celsius. 


Holiday parks and commercial properties may have a leg up with heating time however if they can fill their hot tub up directly from a boiler at the site, as their initial water going in will be a higher temperature. 

Jacuzzi® Hot Tub on decking


Hot tub heat up time is subjective to many factors ranging from product brand, design, insulation, climate, quality of components, heat source and power of heat source, maintenance levels and much more. 

Our recommendation is to allow 24-hours for your hot tub to get to desired temperature and chemicals in the appropriate levels. 

You can always contact your dealer or manufacturer if you want to understand more, for advice, or if you are having persistent issues. 

To work out your hot tub's heat up time, we recommend using online water heating calculators, such as this one

Interested in learning more about Jacuzzi® Hot Tubs? Download our Jacuzzi® Hot Tub brochure for a clear summary of our collections, key features, imagery and more.

Interested in speaking to a member of our sales teams? Click the button below to find your nearest Jacuzzi® Hot Tub showroom in the UK and arrange a visit.