How long does a hot tub take to heat up?

You’ve got your new tub all ready to go. You’ve invited a few (select) friends. The water is rising. But… how long does a hot tub take to heat up?

If you’ve left heating your tub to the last moment, there might be some bad news incoming!

There are a few factors that govern how long hot tubs take to heat up, but you’re looking at at least a few hours – possibly as long as a day depending on the season – before your water is that inviting temperature that’s just right slip into…

How Long Does It Take To Heat A Hot Tub (on average)?

Most hot tub models can reach 38°C (100°F), the recommended temperature of most manufacturers – though we’d actually recommend a little hotter (38.5°C is our favourite) – in about 24 hours. It’s not uncommon for some to take 32 hours though depending on the warmth of the air outside and how cold the water is when you fill your hot tub.

Factors Affecting How Long Hot Tubs Take To Heat Up

How long it takes to heat your tub changes depending on a huge range of factors:

1) Starting Temperature Of The Water

It’s perhaps a little obvious, but the starting temperature of the water plays a big role in how long it takes for a hot tub to heat up.

As a rule, liquids do heat up faster than solids. But the average hot tub holds around 1500 litres of water, which is quite a lot, so it will take some time to heat up that large a body of water.

2) Ambient Temperature Outside

It takes longer to get warm after being outside on a brisk autumn day than it does on a summer evening. In the middle of winter, it’s going to take longer still.

The same logic applies to your tub. Anything you can do to warm up the surroundings will help here:

Shorter term – if you have a hot tub canopy or more permanent cover with shutters, try closing these. If your tub is exposed, it can be worth setting up a windscreen.
Longer term – with the future in mind, planting shrubs or other natural protection is a good plan (the added benefit of this is it makes the area around your tub more pleasing to the eye and more secluded).

3) Insulation

Good insulation will help your hot tub warm up faster. It’ll also make it more likely to stay that way.

If the cabinet your tub is built into has gaps in it – between the seams, for example – this won’t provide much in the way of insulation. Filling those gaps is a smart idea if you want to make things easier for your tub’s heating system.

Equally, where is your hot tub positioned? If it’s built on a surface that doesn’t offer very good insulation, such as concrete, heat will be constantly seeping out.

4) Condition And Maintenance

As you might expect, brand-new tubs – especially models with heating elements that are a good match for the size of the tub – will tend to heat up more readily than older models.

You can stop this typical wear and tear and prevent slower heating by making sure the pump, heater, jets, and even the cover of your tub undergo regular maintenance.

You should also ensure you flush your hot tub through to remove any build up of hard water limescale when you clean your hot tub.

5) Heater Power

Every hot tub is fitted with its own kind of water heater. Of course, the more power the heater has, the shorter time it takes to heat the water.

A heater that’s powerful enough to heat the water fast will also reduce the bleeding effect of colder ambient or initial starting water temperatures.

Hot Tub Heating FAQs

Can I add hot water to my hot tub to speed up the process?

Though it sounds like an obvious solution, it’s not actually a good idea to add very hot water directly to your tub if you want to speed up the heating process.

The end result is often damage to the acrylic shell of the tub itself or melted plastic parts and pipes.

Slow and steady wins the race…

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

Good question! People argue it both ways, but it seems you can achieve the best results when heating your tub by turning the jets on and off intermittently.

Ideally, you want to leave the water alone as much as possible. This is because it will take less time to heat if undisturbed.

However, you want the warm water to be properly circulating by the time you’re ready to get in. This means turning the jets on every so often while heating and leaving them on for a while before you plan to climb aboard.