How long does a hot tub take to heat up?

How long does a hot tub take to heat up?

You just got home after a hard day at work and one of the first things you would like is just to jump in your hot tub and forget about everything? It sounds like a perfect plan but the problem could be water that hasn’t heated up yet. So you might want to know how long does a hot tub take to heat up? In short, it will take you between 4 and 20 hours to heat up the water in your hot tub. It sounds too long and it is, but most hot tubs will heat up the water between 3 and 6 degrees by the hour. It depends on my factors but we will explain that below.


What temperature should a hot tub be?

We mentioned that water heats up between 3 and 6 degrees by the hour. The average water temperature that comes from the tap in the USA is about 50 degrees. In our earlier articles about hot tubs, we mentioned that the maximum recommended temperature is 104 degrees so we talk about an increase of 50+ degrees. So if you have a tub with a lower rate when it comes to heating up (around 3 degrees by the hour) it will take around 16 hours to reach 104 degrees. If your tub is faster (around 6 degrees by the hour) it will take about 8 hours. It's between 8 and 16 hours to be more precise. It can be really frustrating to wait that long but you should buy a floating thermometer and measure the temperature rise. Actually, many floating thermometers can be connected to your phone so you can follow temperature rises anywhere.


Water temperature

Starting water temperature is definitely one of the most important factors in determining how long will it take to heat your hot tub. You can also add some warm water while you are waiting to speed up the whole process but if you decide to go for it, you need to be aware of some issues. First of them is the function that the tub will switch off if the temperature is above 40 degrees centigrade, so keep that in mind. Adding hot water too quickly can damage your tub because the tub needs some time to adjust to new temperatures. Another thing you must have if you add warm water is a filter between the tap and hot tub to eliminate calcium and other metals from the water. So, when you put all this on paper it's a safer option to let the cold water from the tap heat up in its own expected time.


Hot tub size

Size is another factor because it's not the same to heat up the tub with 800 L or a smaller one with 300 L. It's important not to have a too large tub, for example, if you have a hot tub with 5 seats and use only one or two of them then you heat up a huge amount of water completely unnecessarily. Today well-designed tubs will have a heater that fits the size of the tub and water capacity.



Insulation will play a huge role, not only when it comes to warming the water but also to keep the heat later. This could be a problem with older hot tubs where insulation is very poor and that means the heat will easily leak away but also tub will spend much more energy to keep the water warm. If you think your insulation is not good enough you can always use insulation froth and spray it in any voids you find.


External temperature and position of the tub

This is another thing that can affect on time needed to heat up your hot tub. In fact, you can't do anything about that but keep in mind that heating your tub in winter surely will be much longer than in summer when temperatures are around 35 degrees. Just like external temperature, the position can also play a major role when it comes to heating. If your hot tub is placed in a sheltered space with walls around it and the sun beating most of the day, of course, it will help and the tub will heat up quickly. On the other hand, if the tub is in a windy spot and a cooler environment without the sun, the effect will be the opposite.


Hot tub covers

It's well known that hot air will rise and because of that cover is an important item to keep the warm air and help to heat it up faster. There are many covers today, different qualities but if you invest in one of the 'better ones' it could save you a lot of energy and money too. They have a restricted lifespan and it's around 5 or 6 years. No matter how good the cover is, by the time he will absorb humidity from the tub and start to fall apart.


Final thoughts

As we can see there are many factors included in the process of heating up your hot tub. You must look at all of them if you want to reduce warm-up time. Get yourself a floating thermometer and connect it to your phone so you can track it easily. We know it's a frustrating thing to wait for 10 or more hours to get a proper soak but be patient and enjoy your bath.