How do you control the temperature of a wood-fired hot tub?

How do you control the hot tub temperature?

A question we often receive and our answer is actually always very simple: namely, experience. The temperature is not adjustable and a hot or cold hot tub is common in the beginning. The more often you use the hot tub, the faster you will become adept at this. Of course, we do have some tips to help you with this, because experience is there to share with others.

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Don't be too enthusiastic! I say this often, because mostly people are quick to leave the stove on full blast until the temperature is reached. Only here is where it usually goes wrong. After reaching the temperature, with a reasonably full stove, the water will still continue to heat up.

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Therefore, you will soon find out that the water is getting too hot. How hot you want the water to be depends on personal preference and the outside temperature. For now, I'll go with my own preference, which is 38 degrees.

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When I start firing I make sure that the stove is always almost completely full of wood and the ash drawer is well open (10 to 15cm). So that I can heat the hot tub as optimally and efficiently as possible. In between, I refill the stove several times, how often depends on the initial temperature of the water. I always check the thermometer I have floating in my tub.

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The moment the water reaches about 30 to 32 degrees, I always check the amount of wood left in my stove. If it is almost burned out, I fill it to a quarter to keep the fire going. If the stove is more than a quarter full, I do nothing. I close the ash drawer a bit, leaving it open about 5cm. The fire gets a little less air and will burn a little less brightly.

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Now it is waiting for the last degrees, this will not take long! The moment my hot tub reaches 37 degrees and there is still plenty of fire burning in the stove, I close the ash pan. This minimizes the fire and will stop the heating and then the relaxation can begin!

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Do not be afraid that the hot tub will lose its heat quickly if there is no more fire in the stove. The large amount of water in your hot tub will not lose temperature quickly. If you do notice this, start another small fire in your stove with 2 to 4 blocks of wood to maintain the hot tub temperature.

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We always recommend firing with the Swiss method, also called reverse firing. We explain exactly how this works in the video below.