How Long Do Wood Fired Hot Tubs Take to Heat

When purchasing a hot tub the rather extensive selection regarding the various parts may be daunting for some. For this very reason, we at TimberIN try to make this process as simple, informative and smooth as possible. One of the most frequent inquiries of our clients is the expected heat generation of the electric heaters available. To explain what one may expect when purchasing an electric heater, we have prepared this theoretical heat calculation model. Please keep in mind, that the information provided is based on zero heat loss.

 The general formula for calculating the time required to reach a specific change in temperature

  •  Power required to increase water temperature by ΔT degrees in a fixed time (t), assuming no heat loss:
  • Time is taken to increase water temperature by ΔT degrees from a fixed power input, assuming no heat loss:

Example: Time is taken to heat 2 m3 of water from 10°C to 35°C with a 9-kW heater, assuming no heat loss:


2 person hot tub heating time

To save our clients time, we have pre-calculated the approximate heating time for some of our most popular hot tub models. Firstly, comes one of the smallest models, the Japanese Ofuro Bath for 2 persons with polypropylene liner. This model is ideal for clients with limited space, it provides coziness and intimacy without losing the functionality and quality of a larger tub. The polypropylene liner provides a possibility for an air bubble massage system, as well as, a hydro massage system to be installed creating an enhanced experience of the classic hot tub. Polypropylene also provides a waterproof environment; therefore, a client doesn’t have to worry about potential leaks, due to the change of weather. A wide selection of wood types, colors and LED lighting provides a possibility to both personalize, customize and tailor the hot tub to both its surroundings and the clients’ personal taste.


In the case of this model, an electric heater is quite a popular choice, as it provides a clean atmosphere, high mobility and requires minimal maintenance. Regarding heating up water, the volume of the object in question is one of the most important factors. In this case, the coziness of the Ofuro becomes an even bigger advantage as the heating time drops. The inside benches and the slope of the walls reduce the overall water volume even more. For example, if a client were to heat up the water from 10°C to 35°C with a 6-kW heater, the approximate time calculation, would look like this:


6-8 persons hot tub heating time

Nevertheless, clients who are interested in luxurious comfortable and relaxing experiences for both family and friends should look no further than the Wellness Royal model. The best seller of 2017 continues to provide unforgettable moments for clients from all around Europe. High-quality thermo wood exterior combined with the durability of a fiberglass interior provides a long-lasting product, which should not disappoint even the highest standards of our customers.

Much like the previously mentioned Ofuro model, the Wellness Royal provides even more customizability options to satisfy every need of the user. As this model is considerably larger in volume, higher output electric heaters can be accommodated to increase the speed at which the water is heated. For example, if a client were to heat up the water from 10°C to 35°C with a 9-kW heater, the approximate time calculation, would look like this:


Big 12-16 person hot tub heating time

For customers looking to host extravagant and grandiose social gatherings, we offer one of our largest hot tub models, which can comfortably fit an astonishing amount of 16 people. The rectangular shape of this massive hot tub provides easy accessibility for everyone looking to relax in the fusion of Nordic heritage and new age massage technology.

As the volume of the model increases, so does the power of the electric heater. In this example, we will be using the 12-kW electric heater to heat up the water from 10°C to 35°C.

how does wooden hot tub work

Wooden hot tubs heating time 4 – 10 persons

Last but not least, is the Canadian red cedar Wooden Royal model. This model provides the prestige and quality of a fiberglass hot tub while maintaining the natural and exclusive look of the Canadian red cedar finish. This is one of the most unique models currently on the market providing a real sense of individuality.


Red cedar maintains its reputation as the best thermal insulator among the commonly available softwood species and is far superior to brick, concrete, and steel. Both the interior and exterior of the tub can provide up to decades of relaxation and pleasure to the user if properly maintained. If a client were to heat up the water from 10°C to 35°C with a 9-kW heater in this hot tub, the approximate time calculation would look like:


how long do wood fired hot tubs take to heat

The answer is short, 2-3 hours. The exact timing depends on various factors: the size of the hot tub; the size of heater; if insulation was used; the outside temperature.

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