Wood fired hot tub for garden

Hot tub is the simplest variant of a bath tub for the garden. Wait – hot tub? Yes, exactly – because a hot tub is by no means a classic whirlpool.
Hot tub for your own garden or terrace

What is a hot tub?

A hot tub is a type of wooden barrel that is fueled with firewood via a stove and can be placed on the lawn or patio. Traditional hot tubs are still made of wood today, though there are now models made of other materials such as stainless steel or plastic. The hot tub is filled with water, which is then heated to a temperature of  98,6 °F on average.

Wood-fired hot tubs for outdoor use – what is it exactly?

The origin of the classic hot tub comes from Scandinavia, where they have a long tradition. Even today, there are numerous thermal springs there, which are used by the inhabitants for recreation and healing. These springs were felt with a kind of wooden barrels to be able to relax at home in the garden to your heart’s content. Especially in Norway, Sweden and Finland many people own their own hot tub – but also in this country more and more people decide to buy a hot tub for the garden. People often equate the hot tub with a classic hot tub for the garden, but it is not a bubble bath at all.

Rather, a hot tub is a kind of bath barrel, the water of which is fired with wood and heated in this way. The traditional method of manufacturing these tubs is with wood, but they can leak over the years. If you use your hot tub frequently, this can cause the natural material to contract over time, causing leaks to develop in certain areas. For this reason, many people now opt for a modern version made of stainless steel or plastic, which is only covered with wooden slats on the outside for the sake of appearance. The tub can thus be manufactured in one piece – leaks do not occur.

Important: The hot tub is not a whirlpool

Most hot tubs require a power connection. Here an installation should be taken over in each case by a specialist, if one is not a straight electrician. In this way, a whirlpool will continuously incur electricity costs – even if you do not use it at all. An essential feature of a classic whirlpool is its massage jets – but these do not exist in a classic hot tub. Here, the use is limited solely to the warm water, which is supposed to provide relaxation.

However, more and more manufacturers now offer special models with integrated massage jets, if you do not want to completely do without the features of a hot tub. However, integrated jets also increase the noise level, which may not be pleasant for everyone. In addition, it is wonderfully relaxing to sit in a traditional hot tub while listening to the crackling of the wood – more idyllic and cozy is hard to imagine.

The materials of a modern hot tub

As a rule, modern hot-tubs are made of polyethylene plastic, which is enriched by fiberglass-reinforced plastic. Modern hot-tubs with plastic trays offer significant advantages over wooden models. For example, during the production of the tubs, several layers of material are layered on top of each other and then covered with special gels. These act as a kind of protective shield against lime, chlorine, and water deposits. In addition, the gel layers ensure that cracks cannot occur in the tub, and they are resistant to UV rays. Meanwhile, hot tubs come in a wide variety of colors and designs, so they can be perfectly matched to your own taste and style of garden.

How a hot tub with outdoor heater works

In a hot tub with an outdoor oven, an external oven is located at a distance of about 20 cm from the hot tub, which heats the water in the tub through hoses. This creates a natural circulation of water: the water flows through the hoses, can be heated by the wood stove and then flow back into the hot tub. Due to the small distance between the stove and the hot tub, the circulation of the water is favored, and at the same time overheating does not occur. However, if the distance were greater, this danger would exist due to the slower flow of water.

External ovens on a hot tub offer the great advantage of leaving much more space in the hot tub itself. Especially with a larger hot tub, an external heater is a plus, as they allow larger amounts of water to be heated more quickly than with an internal heater. As a rule, the stoves are double-walled and thus offer the possibility of lighting a fire quickly and safely. The ash can be easily removed from an ash drawer after heating. Furthermore, a drawer allows you to regulate the air supply of the stove, which simplifies cleaning. On an external furnace is also a kind of chimney, which removes smoke from the furnace.

The hot tub with internal furnace – how it works

Another option is a hot tub with a built-in oven, which are also called underwater ovens and are located directly in the bath tub. Thus, the oven has direct contact with the water and provides a high level of comfort. It is relatively easy to use, because you can easily add firewood even during the bath. Here it is recommended to install a wooden grate around the stove to protect yourself from possible burns.

Built-in stoves are much more space-saving, but take away a seat in the bath barrel. Usually the stove is made of aluminum and equipped with a chimney. Pipes laid inside reliably transfer heat to the water. The exact power of the stove always depends on the number of pipes and the size of the stove.

What kind of wood is suitable for a wood-fired hot tub?

Soft softwoods such as pine, spruce, or fir have proven to be most suitable for hot tubs. Once a certain base heat has developed in the kiln, harder hardwoods such as walnut, beech, or oak can be added. Hardwoods have a higher calorific value and can generate more heat over a longer period of time – so you need to add firewood less often. It is important that the firewood is as dry as possible. Coal is unsuitable for heating, as it pollutes the stove in the long term, and is also not a particularly environmentally friendly solution.

Tips for the right location of a hot tub

A hot tub looks especially good on terraces or even directly on the lawn. The condition of your own garden should always be taken into account. This is because the hot tub usually remains in its location even through the winter months. It should therefore be placed where it will not be disturbed when not in use. For the winter months, special covers are available so that the tub is protected from frost and ice.

Terraces, of course, often offer the advantage of a roof, in addition, the way into the house is then also short, and you can talk to other people who are not bathing. For example, if you have friends over in the evening, some can enjoy the warmth of the bath and the others sit comfortably together at the table – due to a short distance, you can still easily talk to each other. In any case, the right location should not be chosen too far away from the entrance to the house, if you want to bathe outdoors in the colder season – so you also do not run the risk of catching a cold after the bath.


Frequently asked questions

How long does a hot tub take to heat up?

This question cannot be answered in a blanket manner here. This is because the heating up of a hot tub depends on various factors, such as the heating capacity of the stove, the volume of water in the hot tub, the weather conditions, the firewood and also whether the stove has sufficient draught. In general, however, we can say that a hot tube with a water volume of 800 liters needs about 1.5 hours. But as I said, it also depends on several other factors.

How do I take care of my wooden hot tub?

If you want to use your hot tub for as long as possible, it is important that you take proper care of the wood in the tub. Wood in an untreated hot tub will quickly turn gray when exposed to water and sun, and eventually it will become infested with green algae and fungus. To maintain and protect your hot tub, treat the wood with a stain, oil or varnish. Ideally, this treatment should be done shortly after purchase.

How do I keep the water in the hot tub clean?

Regular disinfection of the bath water is necessary to keep out unwanted visitors such as bacteria and germs. The best known and most widely used method of water treatment is chlorine treatment. The germicidal properties of the disinfectant guarantee a clean bathing experience. In addition, a filter system can be used to filter out small impurities, which is both cost-effective and ecologically sound. This means that the water only needs to be changed every three weeks.

Do I need a permit for a hot tub?

A wood-fired hot tub often does not require a special permit from the chimney sweep or a municipal or local permit. However, care must be taken to ensure that neighbors are not inconvenienced by the smoke. You should still familiarize yourself with the appropriate boundary distances in your community. In some areas, you must maintain a distance of 3 meters from the boundary.

What is the ideal temperature in a hot tub?

The ideal water temperature is 98,6  to 100,4 °F. If the water temperature is lower than your body temperature, you will quickly freeze. A water temperature of 102,2 °F for a long time is uncomfortable and may even be harmful. People with health conditions, especially heart disease and high blood pressure, should adjust the water temperature to their needs.


David Brunner