How long does it take to heat a hot tub before you can relax and soothe your muscles after a long day at work?
Hot tubs and spa pools take between 4 and 12 hours to fully heat up from cold. It mostly depends on the capacity of your water heater and size of the hot tub. During the winter when the water is cooler it will take longer. Inflatable hot tubs take the longest as they have a smaller heater and pump.
Imagine coming home to a relaxing and luxurious heated hot tub that soothes your body and mind. Two thousand years ago the Romans knew of the great health benefits of relaxing in a heated hot tub. The jets of water soothe your body by increasing blood circulation to the areas that are causing aches, pain, inflammation and restrictive moment.
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How Long Does it take to Heat a Hot Tub?
Hot tubs can take between 4 and 12 hours to fully heat up. This is very much dependent on the size of hot tub and the water heater’s capacity.
There are several factors that influence how long it takes to heat up a hot tub.
The temperature of the water source
Mostly you fill a hot tub from a garden hose. The water temperature will vary depending on where you live and the time of year. The colder the water source the longer it will take to heat up.
The air temperature
When the outside air temperature is low it will take a lot longer to heat a spa or hot tub. The water heater will consume more electricity to maintain the temperature when the air temperature is cool.
The water heater capacity
Hot tubs have varying water heater capacities. Some of the small inflatable hot tubs take 12 hours to heat the water from cold. Some of the larger tubs have more powerful water heaters and heat up in only 4 hours to 100F.
The size of the tub
Small tubs with a low water volume will heat up faster than a large tub with the same heater capacity. Allow an extra hour to heat up a large tub.
The hot tub cover
Cover the hot tub to prevent heat escaping. A cover or lid will help speed up the heating process and save power.
An inflatable spa pool will take up to 12 hours to heat up from cold water depending on the temperature of the cold water. Usually the heaters will heat at the rate of 1 to 2C per hour. So cold water that is 15-20C will take 12 hours to heat to 30-35C. The larger capacity spa pools may take a little longer as there is more water to heat.
How long does it take to heat a hot tub for the first time?
Allow for the hot tub to heat up overnight as it will take up to 12 hours depending on the model of water heater and its heating capacity. Always keep the cover on to prevent heat loss and speed up the heating.
How Long Does It Take for a Hot Tub to Warm Up?
When the hot tub water is at the minimum temperature it will take at least 2 or 3 hours to heat up to normal operating temperature. Again this depends on the water heater and its heating capacity.
How long does it take to heat up in the winter?
During the winter the water in a hot tub will be much cooler and require more time to heat up. If you are filling your hot tub during the winter the water supply from your garden hose will be cold. This will require more power and a longer time to heat up.
Typically, it will take an extra two to three hours to heat up a hot tub in the winter than the summer.
How Can I Heat my Hot Tub Faster?
Generally, you are limited by the water heater’s capacity to heat the water. But there are a few things you can do to speed up the heating process.
- Purchase a more powerful, higher capacity water heater.
- Cover the tub to insulate it and prevent heat escaping. The heater may increase the temperature 4 degrees per hour but the water loses 1 degree per hour to heat loss. It’s like 4 steps forward and one step backwards without a cover.
- Turn on the jets to circulate the water which helps to speed up the process. Make sure the water level is above the jets before activating the pump.
- Don’t allow the water to fully cool down. Keep the water heater set to the lowest setting when not in use. When you want to use the hot tub it will only take an hour to heat up again.
- Partially fill the tub from your hot water supply. This really depends on the type and capacity of your hot water supply. If you have a large hot water tank or a continuous supply direct some hot water to your hot tub to speed up the process. Begin by filling the tub or spa with cold water and add hot water into the tub. When the tub is full turn on the jets to mix up the water. Avoid pouring hot water onto the surfaces of the tub or spa as it may damage it. Whether you use the hot tub heater or your hot water system to heat the water makes little difference to the cost of heating the water. The electricity cost will usually be less using the house’s hot water system especially if it’s on off peak power.
Should a hot tub be left on all the time?
Yes. If you are using the hot tub everyday leave the hot tub switched on permanently. Hot tubs are designed to remain heated at all times.
Switching a tub on and off daily will consume more electricity than leaving it on. Once the water is heated to your desired temperature the water heater doesn’t take much power to keep the tub at that temperature. When you allow the tub to cool down it will take more power to heat it up than keeping it at a constant temperature.
This is similar to a home’s hot water system. Water is heated in an insulated tank and kept at a constant temperature. This is the most energy efficient way to heat water and keep it hot.
Keep the tub insulated with the cover on to prevent heat loss.
Why does it take so long for my hot tub to heat up?
Unfortunately, hot tubs take many hours to heat up the water. Water has a high thermal latent heat capacity meaning it takes a lot of power to heat it up from cold.
Once the water is warm it doesn’t take much power to keep it warm.
Read the section above on how to heat the hot tub faster.
Does turning down a hot tub save money?
Yes. When your hot tub is not in regular use turn down the temperature to the minimum setting to save power. Always keep the tub covered to prevent heat loss and water evaporation. A cover will also keep the water clean and preserve your chemicals.
You still need to check the water chemistry every week and adjust the chemistry as required.
Read our post on Hot Tub Chemistry to find out how to look after your hot tub.
Can you fill a hot tub with hot water?
Most would advise not to fill your tub with hot water because you might damage the surfaces or hot tub plumbing.
However, it’s ok to half fill the tub with cold water and top up with hot water from your home’s hot water supply. Ensure the water is mixing and not forming hot spots. When the tub is near full turn on the jets to mix up the water. Don’t turn on the jets until the jets are well underwater to prevent any damage to the pump and filter.
Avoid pouring hot water onto the surfaces of the tub or spa as it may damage it.
It makes little difference to the cost of heating the water whether you use the hot tub heater or your home’s hot water system. When your home’s hot water system uses off peak power it is less expensive than using the hot tub water heater to heat up the water.
What’s the lowest temperature for a hot tub?
The minimum temperature setting varies from one model to the next. Some brands will go down to 80F which is no heating in the summer and minimal heating in the winter.
What is the ideal temperature for a hot tub?
The ideal temperature depends on the climate region and season. Most people will prefer a temperature around 95 to 100F (35 to 38C) for a comfortable spa experience.
Can you turn off a hot tub when it is not in use?
While the hot tub is not in use for more than a week turn off the water heater to save power. Keep the water pump on to circulate the water and sanitizer. When the water is not sanitized and circulated the water will become stagnant. Stagnant water will encourage algae and bacterial growth which makes the water green and smelly. This is not safe for bathing as people can become infected with diseases.
How much extra electricity does a hot tub use?
Hot tub motors and heaters do not use as much electricity as you think. The new spas and hot tubs have energy efficient pumps and heaters.
Depending on usage, a hot tub adds an extra $20 to $50 per month to an electricity bill. If you live in a cold climate the heating will cost more than a warmer region but it won’t be excessive.
Conclusion
Hot tubs and spa pools are a great way to relax and improve your health. The hot water is proven to stimulate your immune system to combat the effects of many medical conditions. Spas increase blood circulation to the areas of your body that are causing aches, pain, inflammation and restrictive moment.
However, it takes time to heat up the water before you can enjoy yourself in your hot tub. Always keep the water heater on and set to a low temperature. Plan when you want to use the tub. Set the timer to activate the heater several hours before you need want to use it.