How long does it take to heat a hot tub (and how to speed it up)?

Posted by Nick Clamp in Maintaining a Hot Tub Guides on 14th March 2022

Most hot tubs take between four and six hours to heat up.

But you can speed that up by following the tips we’ve laid out in this short guide.

Read on to find out how to get your home spa up to temperature as quickly and cost-effectively as possible.

What temperature should a hot tub be?

Most people like their hot tub between 36°C and 38°C, while it’s recommended you drop that to 35°C if kids will be using your spa

If you prefer your hot tub a little less hot – or if you’re looking to use your spa to cool down on a hot summer’s day – most go as low as 26°C. At the other end of the spectrum, the highest recommended hot tub temperature is 40°C, as anything higher can be dangerous to sit in for an extended period.

How long does it take to heat up a hot tub?

If your hot tub is in good working condition, it’s water will get between 3°C and 6°C hotter every hour until it hits the temperature you’ve set. This means your hot tub will usually take between four and six hours to heat up after you’ve refilled it (or filled it for the first time).

Of course, the temperature outside will have a big impact on how quickly your spa heats up. You’ll have to wait a lot longer to enjoy a soak during a snowstorm than during a heat wave.

The good news is that hot tubs are very effective at maintaining their heat once they’re up to temperature. So, you’ll only have to wait for your hot tub to heat up when you’re filling it up for the first time or after refilling it as part of your regular hot tub maintenance routine – the rest of the time you’ll be able to hop straight in.

How can I make my hot tub heat up faster?

Luckily, there’s plenty you can do to make your hot tub heat up faster – and keep your hot tub running costs down at the same time.

Tick all these boxes to make sure your home spa gets up to temperature as quickly and efficiently as possible: 

Make sure you’ve got a first-class cover

Photo © Hot Tub Studio

Hot tubs lose around 60% of their heat through the surface of their water. Which means a poorly insulated, cracked, or damaged hot tub cover that does a terrible job of trapping your hot tub’s heat in could cost you an arm and a leg over the years.

So, make sure your spa has a high-quality, thoroughly insulated cover. Look out for one that’s filled with high-density polyurethane foam, locks in place, and has a ‘continuous heat seal’ that creates an airtight seal. The best covers are also at least four inches thick at the centre and have tapered edges so rain and snow run straight off.

Want to test whether your hot tub’s cover needs replacing – or whether the cover of a spa you have your eye is up to scratch? Place your hand on the top of it while the hot tub is running. If it’s room temperature, that means it’s trapping in heat as efficiently as possible.

Invest in quality insulation

How well a hot tub has been insulated is one of the biggest factors in how long it takes to heat up – and how much it costs to run.

Your hot tub will heat up as fast as possible if it’s been fully insulated with high-quality foam. Partially foamed hot tubs are a good second choice if a fully-foamed model is out of your budget – although your monthly energy bills will be higher, so bear in mind that it might actually work out as more expensive in the long run. 

We’d strongly recommend you avoid home spas that are only insulated by a thermal wrap or have no insulation at all. Only buying from WhatSpa? recommended hot tub brands is a simple way to avoid being stung by a cheap grey import that misleads you on how well it’s insulated in its product description (a common corner for less reputable brands to cut).

Make sure your hot tub’s components are in ship shape

Your hot tub’s water heater, pump, and jets are the “engines” that drive up its temperature. Which means that if your spa has first-class components, it will heat up a lot faster. That’s why – if you can afford the upfront cost – it often pays to go for a high-end hot tub rather than a middle-of-the-pack option, as the better components and insulation will make a serious difference to your hot tub running costs.

Of course, a broken or worn out heater is going to take a lot longer to bring your hot tub up to temperature. So, no matter how high-end your home spa is, follow a proper hot tub maintenance routine to keep its components in proper working order and working as effectively as possible.

Plan your landscaping

How protected your hot tub is from the elements can have a big impact on how fast it heats up.

If your spa is sitting in a windy spot it’s going to take longer to get up to temperature – and not be as nice to sit in to boot. That’s why it’s always a good idea to install your hot tub in a natural alcove if you can. 

If your only option is to leave your spa at the mercy of the elements, you can cut the time it takes to heat up by installing a windscreen, planting a hedge, or building hot tub housing around it to act as a buffer from the wind. This will also have the added benefit of lending some extra privacy to your soaks.

Turn the jets on

Turning on your hot tub’s will help circulate the heat from its heaters around the whole body of water and prevent cold patches from forming. This simple hack can make a big difference to how long your spa takes to hit the temperature you’ve set.

Use a thermal spa blanket

A thermal spa blanket is an insulated sheet that floats on your hot tub’s surface and helps trap the heat in. Placing one on your hot tub’s water while it heats up will help bring it up to temperature as quickly as possible – and help keep it there when you’re done using it, too. 

Should I leave my hot tub on all the time?

Photo © Hot Tub Studio

It might seem counterintuitive, but leaving your hot running all the time will actually save you money.

Firstly, turning your home spa off every time you get out of it would mean having to wait a few hours before you can use it again. And no one wants that. 

Plus, since a quality home spa is so well insulated, it can very efficiently maintain a steady water temperature. That means it will also cost you a lot more to heat your hot tub from scratch every time you want to hop in for a soak.

It’s so much more efficient to keep your hot tub running than turning it off and reheating it that it’s actually more cost-effective to turn it down to around 30°C while you’re away on holiday for a week or two rather than turning it off completely and heating it up from scratch. Plus, your spa will get up to temperature a lot faster when you get back (just be sure to shock your hot tub before you get in). 

The only time it’s worth leaving your spa off for an extended period is when you winterise your hot tub after deciding you’re not not going to use it over the cold months.

Summing up

Most hot tubs take between four and six hours to heat up with smaller hot tubs generally take a shorter amount of time. Follow the tips we’ve laid out in this guide to make sure yours gets up to temperature as quickly and cost-effectively as possible.

Looking for more hot tub maintenance tips? Grab your free copy of the latest edition WhatSpa? magazine for the latest guidance on how to get the most from your home spa and our picks of the best buys on the market today.

About the author

Nick Clamp

I am the Editor-in-Chief at WhatSpa? Media Group and my job is to keep you informed about the very latest hot tubs on the UK market... the best job in the world! When I'm not being deluged with press releases and hot tub brochures I enjoy keeping fit and participating in endurance events including triathlons and distance running.

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