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Temperature control - what's right for your hot tub?

2 years ago 1890 Views No comments

game character thermometers

One question always asked in relation to owning hot tub is: Should we keep our hot tub constantly warm, or is it better to turn it off after usage. This is a very understandable concern as energy prices remain high and people want to make sensible choices.

While it is difficult to put a meaningful price on hot tub costs  because of factors such as different energy suppliers, your own usage, how often you use it  it is easier to lay down some guidelines that will help you make the decisions allowing you to run your hot tub as cheaply as possible.

Should you keep it constant?

The chances are, if you keep the hot tub constantly heated you might use it more regularly, but will you use it enough to justify keeping the water warm at all times?

Without throwing a lot of numbers and calculations around, industry experts say that its cheaper to heat the water when you want to use the hot tub rather than keeping the tub constantly hot, unless you really do use the hot tub every day or at least five times a week. Hot water will lose heat to the environment, particularly when the weather is cold. The greater the difference in temperature between the environment and the hot tub, the greater the ensuing heat loss.

We can demonstrate this point by using the example of a cup of tea. The time it takes for a cup of tea to become drinkable once it is served in the cup is quite quick  it cools quickly in the environment. However, as the tea approaches the temperature of its surroundings, it cools far less dramatically and stays warm while you drink it.

Heating costs

It is difficult to generalise about the heating requirements of a hot tub as the models vary so greatly in size, model, insulation, placement and many other factors. But we can look at the cost of heating the water.

A hot tub that is designed to accommodate eight people will hold about 500 gallons of water. To raise the temperature of a hot tub from about four degrees celsius (in the winter months) to about 37.5 degrees celsius, takes about 250,000 BTUs, which is roughly 75 kWh of energy. You only have to prove up how much a kWh costs from your energy company to see what this costs. As your hot tub constantly loses heat as the water temperature meets the environmental temperature, you will be using 75kWh of energy every day to keep the hot tub constantly warm.

Invest in quality

However, if you plan on using the hot tub every day, or on a very regular basis throughout the year, then maintaining the heat is the way to go. Our advice at this point is to invest in a high quality hot tub cover. Most of the heat in shot tub is lost through the hot tub cover  one user in the USA keeps a close tab on his energy usage and he says that it costs him an average of $30 per month to keep his hot tub working all year round, but that figure would rise to $50 a month if he did not have a high quality cover.

The best thing to do is to talk to your hot tub provider about a suitable cover to meet your needs. Each cover has an R-value, which is the numerical value of the insulation qualities of your cover. The more you are planning to use the hot tub and keep the temperature constant, the more it will pay you to invest in a good cover with a high R-value. As a very rough guide, an R-value that is twice the numerical value of your existing cover will retain the heat for twice as long. In the long run, if you are planning on running your hot tub throughout the colder months, then the investment you make into a cover will be repaid through energy savings.

Make the right choice for you

As a guide, if you are using the hot tub sporadically, then turn it on in the morning if you plan to use it that evening. However, if you are using the tub more than six or seven times a month, you may want to consider running it all the time and investing in a very high R-value cover for the hot tub.

This is one situation where getting the maths right will pay dividends in the long run.

Related article: Save Money with a New Hot Tub Cover.


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