Wood Fired Hot Tub Guide

A wood-fired hot tub is the ultimate in-home water recreation. The easy-to-use and eco-friendly wood burning hot tub, while not a new technology, is seeing a resurgence in popularity.


In today’s face-paced world, people are seeking a way to find work-life balance and to enjoy some of life’s simple pleasures.

Nothing is as relaxing as a dip in a hot tub.

Read on to learn more about what makes a wood-fired hot tub so desirable, and what you should know before you buy a hot tub.

A History of the Wood Fired Hot Tub

First, let’s discuss the history of hot tubs and what led to the wood-burning hot tub we know of today.

Indeed, the history is quite interesting. Throughout the ages, people were always trying to find ways to enjoy water before the spa industry was ever a “thing.”

Hot Springs: Where it All Began

Long after the primordial “hot tub” grew their own multi-celled organisms, humans found their way to the hot springs that formed from pools of water and natural thermal vents in the earth. These natural hot springs were known for their high mineral content, such as calcium and lithium.

These made springs natural destinations for people seeking therapeutic benefits.

Hot springs exist on all the continents of the planet. Popular tourist destinations still visited today include the hot springs of Nachikatsuura, Wakayama, Japan and the Rio Hondo Hot Springs of Argentina.

Soon enough, ancient civilizations were altering hot springs to make them more comfortable. That’s where thermal complexes, or thermae, came into being.

Artificially Constructed Baths

Thermae were commonplace in almost all Roman cities. They were used for socializing, bathing, and known for medicinal folk medicine treatments. If baths were not heated by a natural hot spring, water was heated by a log furnace before being piped into the baths.

Men and women had separate entrances and areas in bathhouses. Many also housed an outdoor gymnasium where men could play games and exercise with weights. Then, men would oil their bodies, shower and enjoy the baths.

For many Romans, bathhouses were an important place to do business and socialize with other community members. In addition to that, bathhouses offered significant resources to people who did not receive access to certain levels of society. For instance, many bathhouses had libraries and areas where poetry was performed. Thermae were places to relax and learn.

After the fall of the Roman Empire, these facilities fell into disuse and public bathing was discouraged by the Catholic Church during the Dark Ages.

Hot Water in Homes

Believe it or not, the ancient Egyptians had bathing chambers and showers in their homes. Well, showers were mostly servants pouring water over their heads, but still, it was a sophisticated practice for that time in human history.

In some cases, servants would bring hot water from springs or heat the water before use in large vessels.

Eventually, water storage tanks were heated to allow bathers to enjoy warm water in the comfort of their own homes.

Japanese Influences

The Japanese culture likely had the greatest influence on the creation of the modern hot tub.

Due to the volcanic nature of the Japanese islands, there are many hot springs where people have bathed over the centuries. The country’s love of soaking in natural hot tubs led them to develop three kinds of hot baths:

  1. Ofuros: Ofuros is a wooden Japanese bath. They are short and steep-sided. Commonly found in homes and some bathhouses, they also appear in hotels, guest houses, or temples.
  2. Sentōs: Sentōs are bathhouses like traditional Roman bathhouses. They are artificial, and water is heated by furnaces or boilers.
  3. Onsens: These are natural Japanese hot springs. Again, since Japan is volcanically active, there are 1000s of onsens scattered throughout the country. Some are outdoor, some indoor, and they are run by either the government or private owners. Generally, onsens, like sentōs, are separated by genders.

All Japanese bathhouses have rules regarding etiquette. You can learn more about these rules here.

Undoubtedly, the Japanese have had a great influence on the spa culture and modern hot tubs.

Modern Hot Tubs

After World War II, troops brought back the spa and bathing traditions of Japan.

In the 1960s, creating household hot tubs from wine barrels, vats, tanks, and other large vessels was commonplace. People in California began creating tubs made of cement, gunite and other materials. More often than not, these hot tubs were wood fired.

Today’s hot tubs vary. Hot tubs are jetted baths that electrically maintain the heat of water. Some are free-standing, portable, or built into landscaping. Additionally, wood burning hot tubs as popular as typical modern hot tubs.

Why a Wood Burning Hot Tub?

For people who enjoy water recreation but do not want to invest in a product that uses a lot of energy, a wood fired hot tub is ideal.

Use in rural locations is not a problem since there’s no electricity. This makes a wood fired hot tub accessible for various festivals, home uses, and more.

Let’s talk more about the uses of a wood fired hot tub.


These days, music festivals and other multi-day events are quite elaborate. Before, after or during musical sets or events, hosts often schedule extra activities to keep attendees entertained. A set of wood burning hot tubs entices people to relax, soak and socialize. Soaking in a wood fired hot tub re-energizes people while allowing them to engage in a unique activity.

Home Use

For the serious user, having a wood fired hot tub at home means unlimited, on-demand access. Bathing in hot water has a number of health benefits including better sleep, diminished pain, lowered blood pressure, and reduced stress. bathhouses and spas are not always accessible or budget-friendly. Having a wood fired hot tub at home creates a personal oasis that’s consistent and private.

Rental Spaces

Vacation homes, rental spaces and other for-hire facilities see increased popularity when a wood fired hot tub is added to the amenities. A wood burning hot tub is novel for many. The intriguing design creates a unique aesthetic that draws in the adventurous and romantic.

Parties and Events

A wood fired hot tub elevates the mood for any event. Although it’s unconventional, under a sky at any time of year, a wood fired hot tub is a versatile addition. Party throwers should offer a variety of beverages to keep attendees hydrated and happy. People naturally gravitate toward a hot tub. Practically, wood fired hot tubs are easy to manage, too. So, whether you’re attending the party or throwing it, you’re sure to enjoy using a wood burning hot tub.

How is a Wood Fired Hot Tub Made?

Wood fired hot tubs are unique compared to portable hot tubs, jetted hot tubs, and other outdoor spa baths. Indeed, in looks alone, a wood fired hot tub has so much to offer. Let’s take a deep dive into the details of hot tubs, how they’re created, and how to maintain them.

Anatomy of a Wood Fired Hot Tub

Surprisingly simple, a wood burning hot tub features:

Tub: The tub is a basic round structure made of a variety of materials. A tub may be made of wood, PE plastic, stone, etc. Tubs vary in diameter depending on the capacity of the tub. Many tubs come with a drainage set for easy water filling and removal.

Bench: Often built into the shell of a tub, a bench provides comfort for those sitting in the tub. For some models, a bench may be made from wood and inserted into the tub. A good bench has no sharp edges for added comfort.

Wood Fired Stove: The important heating element mustn’t be forgotten! A wood fired stove comes in a variety of sizes depending on the capacity of a tub. Stoves may be internal (within the tub) or external. Important to note, external stoves take longer to heat tub water compared to submersible internal stoves. However, the advantage of an external stove is that it does not take up room in the tub. Stove pipes on both external and internal heaters carry smoke away from users.

Hot Tub Manufacture

Depending on the model of wood fired hot tub, manufacture varies. For instance, at Swedish Hot Tubs, our manufacturing facility is in northern Europe with specialist roto-moulding equipment. We have distribution facilities in Shropshire where we can assemble and ship out our tubs.

We create hot tubs using PE roto-moulded into our custom designs. This method ensures our hot tubs are completely recyclable, almost indestructible and safe for families.

Most hot tub manufacturers will offer both internal and external stove options depending on the needs of the consumer.

Popular Wood Burning Hot Tub Materials

There are a few different materials used in the manufacture of wood burning hot tubs. In general, a wood burning hot tub requires materials that are water resistant, mould resistant, able to withstand high temperatures and also aesthetically pleasing. Below are some different materials offered to create a modern wood burning hot tub:

Cedar: If you have been researching wood fired hot tubs, you’ve undoubtedly seen cedar wood mentioned as a common material. When cedar gets wet, it swells, leaving a watertight seal. As a durable wood, it’s just as strong wet as it is dry. Cedar also naturally discourages mould growth. Cedar even repels bugs and insects. Therefore, cedar is often used to line closets. For people using the hot tub, cedar gives off a lovely aroma that enhances the spa experience.

Spruce: Spruce wood is very light in colour and a popular choice for hot tub finishes. Unlike cedar, it’s not naturally resistant to rot and does require some maintenance. Treating the wood is as easy as wiping it down with linseed oil. Spruce’s strong, stiff characteristics are what make it popular amongst hot tub enthusiasts.

Thermowood: Thermowood is a processed and chemical-free wood that looks darker than cedar or spruce. It is far more weatherproof than natural wood. Also, unlike natural woods, Thermowood does not leak any resins when heated. Due to its manufacture, hot tubs made with Thermowood are lighter, less likely to become deformed, and perfect for outdoor use.

Polyethene: Moulded polyethene, or PE, is commonly used for the inner shell of a wood burning hot tub. PE is recyclable, and for that reason, often the choice for eco-conscious consumers. In addition, PE holds heated liquids well, is easy to clean, and because there is no welding or seams, is leakproof.

Types of Wood Fired Hot Tub Heaters

There are two types of heaters for a wood fired hot tub: internal and external.

Internal Heaters

Internal heaters sit directly inside of a wood burning hot tub. That means 100 per cent of the heat it generates goes into heating the water. It uses natural convection to heat the water. Naturally, less dense hot water rises to the top and cold water to the bottom. An internal heater needs to be installed on the side of the hot tub or fastened to the bottom otherwise the air volume in the heater would cause it to float. Wood is fed into the top of the heater with an air vent located above the water line that vents air into the heater. The chimney draws smoke away from those in the wood burning hot tub. The fire is adjusted by manipulating the air intake.

An internal wood fired hot tub heats quickly than its external counterpart, but it does take up more space in the tub.

External Heaters

External heaters are located outside the hot tub. Those who prefer an external heater will need to ensure they have the space to accommodate it. External heaters rely on a thermal syphoning, a process by which the heater, placed lower than the tub, circulates naturally rising hot water. This process does take time, however. Some large tubs require hours to heat. Of course, an electric pump can decrease the heating time significantly. For people who want a lot of tub space, the external heater is the best option.

Choosing Which Heater is Right for You

There are clear benefits to both types of tub heaters. To keep it simple, here are a few things to remember when choosing between an internal and external heated wood fired hot tub:

  • Internal heaters have less space within the tub but take less time to heat.
  • Internal heated hot tubs need less space for installation.
  • Externally heated tubs have larger tub capacity but take longer to heat.
  • External heaters need more space for accommodation.

Wood Fired Hot Tub Accessories

Take a wood fired hot tub to the next level by accessorizing. For optimal comfort and function, here are some available accessories:


Temperature control in a wood fired hot tub is manual. Therefore, you need a way to tell what the temperature is, when to dampen the fire, and when the water is ready for use. For ideal bathing, it’s recommended that you allow the water temperature to reach 38 degrees.

Sand Filtration

A sand filter works by pumping water into a multi-port valve on top of the filter tank. This diffuses water onto sand inside the tank. The water works its way through the sand, thereby depositing dirt and other debris onto the surface. The newly filtered water then passes through fine holes at the bottom of the tank and is forced up back into the hot tub. For people who want clean water all the time, a sand filter is a valuable accessory.


Take hot tubbing to the next level by installing a bar. A bar allows you to place beverages, books, snacks and even candles near the wood burning hot tub. Creating a great ambience improves the experience exponentially. During parties, a bar provides a place for items so that the host and guests don’t have to leave the hot tub to enjoy their time together.


For stairs, the goal is function that is pleasing to the eye. Materials such as Thermowood have a decreased chance of rotting or warping. Whatever stair material is chosen, be sure to prioritize durability.


Lids impart extra protection from the elements and minimize heat loss between use. Lids may be made from a variety of materials, including leather and foam insulation. Covers are available for both external and internal heater hot tubs.

Wood Fired Hot Tub Maintenance

Properly maintaining a wood fired hot tub is the key to its longevity and your enjoyment. Learn all you can about hot tub maintenance to keep your wood fired tub in top shape.

Keeping the Water Clean

The most crucial part of maintaining a wood burning hot tub is sanitation. Sanitizing kills harmful bacteria that like to grow in warm water. To do this, you need to check levels of sanitizer and the water’s pH. Acidic water irritates the skin and corrodes your tub while alkaline water leaves deposits and stains. Using test strips, you can find out what the water’s pH is. Then, you can drop in special additives to equalize the water. The recommended range for pH is balanced between 7.2 and 7.8.

When it comes to the removal of bacteria and organic matter like algae, we suggest an oxidation shock. We recommend only non-chlorine shock due to due to material corrosion.

Finally, the best way to always ensure water clarity and sanitation is to wash before entering the hot tub.

Daily Maintenance

There is no daily maintenance required unless you plan on using your hot tub daily. Before use, you’ll want to test the water with test strips for pH balance and sanitation levels. Adjust levels as needed.

Long-Term Maintenance

Every so often, you’ll need to empty your wood fired hot tub completely and give it a good scrub. This ensures no algae builds up in hard to reach areas. Currently, it’s important to check for any damage in the tub because catching something early makes repairs far easier.

What Wood Should You Use?

For starting your fire, paper and kindling are a great way to get things going. Dry wood in a variety of sizes is desirable as it allows you to feed the fire as you need.

In Freezing Weather

Hot tubs are designed to work in cold weather. Depending on your local climate, how much you use your tub, and if you have access to electricity, there are ways you can cope with freezing temperatures.

First, an appropriate insulated cover will go a long way to keep your hot tub warm. For instance, you should not lose more than 15 or so degrees per day unless the weather is extreme.

However, if you plan to take an extended trip away from your wood fired hot tub, here are a few things you can do:

  • Drain all but a few inches of water and allow it to freeze. A small amount of frozen water should not cause any damage to the tub structure.
  • Float a few empty beverage containers. If the water freezes, the bottles will absorb some of the shock. This is a good tactic when access to water is limited.
  • If the water in your tub freezes completely through and quickly, we do not suggest starting a large fire. Ice takes a while to melt and if water can’t flow, the fire may burn too hot and damage the stove. Make sure you make a small fire and work your way up from there as the ice melts. Extra caution is suggested with this method.
  • If the water only freezes a few inches, feel free to start a fire slowly and build it up until the ice melts.

How to Use a Wood Fired Hot Tub

A wood fired hot tub does not require electricity, however, there are some techniques to its manual operation.

Using a wood burning hot tub should be like maintaining a camp stove. Once the fire is lit and an ideal temperature is attained, it’s all about holding that temperature.

To light a wood fired hot tub, we suggest using clean-burning paper or kindling to ignite the fire. This should be placed on logs.

As the tub begins to warm, heat tends to stratify in the tub, with cooler water sinking to the bottom. Therefore, stirring the water with a large paddle is one way to get consistently warm water before dipping in.

It’s important to keep in mind that the more wood you use to heat the stove, the faster your water will reach the desired temperature and the longer it will remain hot. If the water gets too warm, the fire should be dampened and airflow to the stove reduced.

Improving Heat Time

For the fastest heating time, use split, dry wood (like birch). Feed the fire slowly with small quantities of wood. If you add too much wood, the stove may heat unevenly, which extends the heating time. As a general guideline, the heating chamber should be no more than ¾ filled with wood.

To Adjust the Temperature

The recommended water temperature is +39°C. Using the thermometer, check the temperature. When the water is two to three degrees from the optimal temperature, restrict the airflow to the heater using the draft damper. Then, add a small amount of wood. The temperature should increase just a few degrees before stabilising. If the water is too warm, add cool water or snow.

Heating While Using

Closing airflow to the flame slows the intensity of the burn. After, the temperature of the water will rise slightly by only a few degrees or remain the same. If the bathing water becomes too hot, add some cool water.

Personal Safety

As with any pool of water, safety is of the utmost importance. To ensure your safety, we suggest the following:

  • Keep your distance from the wood fired heater while operating.
  • Do not leave your wood fired hot tub unattended while lit.
  • Children should not enter the hot tub unless under the supervision of an adult.
  • As with any fire, you should have a fire extinguisher on hand.
  • Enter and exit the tub with care as wet surfaces may be slippery.
  • Do not jump or dive into the tub.
  • Prevent dehydration by drinking plenty of water.
  • Check the temperature of the water before entering.
  • Pregnant women, the elderly, those with health conditions and infants should exercise care and consult a doctor before use.
  • Do not use a hot tub while under the influence.
  • Exceeding the capacity of the wood burning hot tub may result in damage or injury.

Fire Prevention

We don’t mean to prevent the fire you use to warm the wood fired hot tub. With any fire, some precautions should be taken. For instance, avoid placing flammable items near the stove where the fire is burning. The chimney becomes very hot and should also be avoided.

If your stove is placed on a flammable surface, such as a wooden deck, extra measures should be taken to protect the floor. Contact a fire prevention expert for concerns of this nature.

A Note on Placement

For these reasons and more, the location of a wood fired hot tub is crucial for safety. Surfaces should be chosen and prepared with safety in mind. Hot tubs should be placed on level surfaces made of concrete, wood, stone or a flat lawn. For obvious reasons, the surface should be able to bear the load of a full hot tub.

Benefits of a Wood Fired Hot Tub

A wood fired hot tub offers more than just a spa experience. They are innovative in their design, easy to use, and therapeutic. Let’s uncover all the benefits of owning a wood fired hot tub.

Aesthetically Appealing

A wood burning hot tub adds appeal to any yard, festival or event. The natural wood finishes emote nature and comfort. Beside a crackling fire and under the sky, what more can a bather ask for? Rustic yet modern designs are compatible in almost any setting.

A wood hot tub made from cedar, spruce, or Thermowood is beautiful. Its round, symmetrical shape appealing, the natural grains in the wood are visually pleasing. If having natural materials around your home or property is a priority, a wood burning hot tub is preferable to any acrylic tub.

Enduring Investment

When it comes to savings, a wood fired hot tub can’t be beat. Each tub is durable and well-made to stand the test of time. With proper maintenance and cleaning, you can count on enjoying a wood fired tub for 15 to 18 years. Of course, using harsh chemicals and inconsistent use will dramatically shorten the lifespan. The stoves must also be cared for properly. If rain or water enters the stove between uses, the water may mix with ash to create a caustic environment that can rust the stove. Otherwise, with proper care, stoves should last the life of the wood fired hot tub.


Of all the hot tub products available on the market today, a wood burning hot tub is one of the most cost-effective in both initial cost and maintenance. Comparable acrylic or fibreglass hot tubs with complex jet systems are far costlier. Maintenance of the system often requires a professional repair person.

In terms of energy savings, electric hot tubs cost far more to operate. As long as you have a source for wood, you can enjoy the benefits of your wood fired hot tub.

Options for All Needs

Every hot tub manufacturer has different wood burning hot tub collections. Each is created with customer needs in mind. Not all wood fired hot tubs are created equal. Whether you need something small to accommodate a couple or one that fits a large family, the right wood fired hot tub is available.

At Swedish Hot Tubs, we have four options for our customers:

  • Essential: The Essential range collection features a one-piece polymer molded tub made from recyclable PE plastic and a quality wood surrounding the tub. You may choose from three quality wood surrounds: Spruce, Red Cedar, and Thermowood. You can also opt for a wood finished rim or a standard PE plastic rim. The Essential Swedish Tub Range offers a choice of a 20 to 35 KW heater. Heaters are an eco-friendly way of heating your two to six-person tub.
  • Premium: The Premium collection of Swedish Hot Tubs are accompanied by an aluminium or coated wood fired heater. The Premium Swedish Tub range is available with a choice of a 23 to 45 KW heater. This collection features hot tubs that accommodate four to six people.
  • Exclusive: Like the Essential and Premium lines, the Exclusive collection features a moulded tub with wooden surround. Surrounds are available in three options: Spruce, Red Cedar and Thermowood. In addition, the tubs come with a 25 to 45 KW heater and accommodate four to six people.
  • Tub Hire: Need a wood fired hot tub for Christmas, a wedding, or Valentine’s Day? Tub hire is available! Our standard packages include a Premium Swedish Hot Tub, wood to keep your hot tub warm for hours, an operation manual and on-demand training, and free delivery within 30 miles of our depot.

Therapeutic Benefits of Hot Tub Use

Many cultures value the health benefits of soaking in a hot bath. Now there’s science to support folk medicine claims. There are a variety of therapeutic benefits to hot tub use.

Hot Baths and Energy

Physiologist Steve Faulkner, PhD studied the body’s ability to burn calories when core temperature was raised. According to the study, “The researchers found energy expenditure increased by 80 per cent sitting in a hot bath for an hour. This didn’t approach the energy expenditure from riding a bike for an hour but was extremely close to a brisk 30-minute walk.” That’s good news for people who love to take a long soak!

Healthy Sweat

Sweating helps you remove toxins, like phthalates found in personal care products, from your body. Be it through exercise, saunas, or a long hot tub soak, sweating is good for you. Sweating is also a good way to get rid of extra fluid on your body, such as water weight. However, be sure to drink plenty of water while bathing in order to replenish what is lost during a soak.

Improve Glucose Sensitivity

Heat shock proteins, a molecule seen in all animals when stressed, are increased when exercising or during “passive heating” such as a hot bath. Heat shock proteins regulate blood glucose levels. Manipulating heat shock protein levels through a hot bath is one way to regulate blood sugar and get some of the benefits of exercise.

Stimulate Your Immune System

Increasing your core body temperature to 38.2 degrees celsius triggers an immune response (much like a fever). Frequent bathing or sauna use can even lower your risk of getting the common cold or flu.

Fight Pain

Nothing feels better on achy joints and muscles than a hot bath. Saunas help the endocrine system by the secretion of growth hormones. These hormones help rebuild muscle and tissues. In addition, heat reduces inflammation of the body’s tissues.

Get Better Sleep

Sleep matters, and baths can help fight insomnia and poor sleep habits. A study in Finland showed, “Furthermore, sauna, shower and bath, stability in life, psychological factors, positive experience in work, satisfactory sexual life and good and quiet sleeping environment were reported to have positive effects on sleep.” A long hot soak assists the process of regulating our circadian rhythm. As a body cools down from a hot shower, heart rate drops, breathing rate, and digestion. This is the best way to sleep.

Be Heart Healthy

According to a 2015 study out of Finland, “Increased frequency of sauna bathing is associated with a reduced risk of sudden cardiac death, fatal coronary heart disease, fatal cardiovascular disease, and all-cause mortality. Further studies are warranted to establish the potential mechanism that links sauna bathing and cardiovascular health.”

Environmentally Friendly Recreation

A wood burning hot tub is an eco-conscious upgrade to your home that is sure to entertain your family for years. When it comes to guilt-free spa products, a wood fired hot tub is the way to go.

Energy Savings

If you have wood, you have power. It’s a simple idea, but an eco-friendly one. For those with access to a plentitude of timber, heating a wood fired hot tub is no problem. Even people in rural areas with limited access to electricity can enjoy the comforts of a soaking tub.

There’s no need to burn fossil fuels when you use a wood fired hot tub. With a renewable resource such as wood, there are fewer drawbacks to using a hot tub.

With a proper wood fired hot tub cover, maintaining temperatures is easy too. Lids keep water warm until the next use. Therefore, less wood is needed.

Chemical-Free Water Option

Although not mandatory, you have the option of not using chemicals in your wood fired hot tub. With a molded interior, either option is available to you. However, with some all-wood designs, chemicals are not an option. For untreated water, you can reuse water for your lawn or for washing your deck.

If you decide to chemically treat your water, there are a variety of products on the market that are more environmentally friendly and not chlorine based.

Recyclable Design

At Swedish Hot Tubs, all our designs include roto-moulded PE liners. Our hot tubs are completely recyclable, safe and perfect for extended use.

Also, because our tubs are locally manufactured, there is less fuel needed to transport our tubs.

Water Saving

With a PE molded design, seating assists in saving water. Molded tubs require less water than those with an open wooden bench. Another way to save water is to opt for an internal heater, which takes up more space in the tub, thereby displacing water. Less water means faster heat times, less water waste, and less wood needed to heat the tub.