Thermo Black 150 Steam Indoor Sauna

What is a steam sauna and how does it work?

A steam sauna uses an electric heater filled with sauna stones. Pouring water over the hot stones creates steam and increases humidity, giving you the traditional Finnish-style sauna experience with hot, humid air and a stronger, more intense heat.

How hot does a steam sauna get?

Steam saunas usually run at higher air temperatures than infrared models. The final temperature depends on the heater output, cabin size, and insulation. Some people prefer short, intense sessions, while others enjoy a slightly milder heat with added steam.

Do steam saunas need plumbing?

No. Steam is produced by pouring water onto the heated stones by hand. There is no built-in water supply or drain inside the sauna. The room around it simply needs normal ventilation so any moisture can clear when the door is opened.

What power supply does a steam sauna need?

Steam sauna heaters vary by model, with many home units ranging from 3 kW to 9 kW.
Important: Any heater above 3 kW must be hard-wired on a dedicated circuit by a qualified electrician. Always check the heater rating before installation.

How long does a steam sauna take to heat up?

Most steam saunas take around 30 to 45 minutes to reach temperature, depending on the heater size, cabin volume, insulation, and room conditions. Allowing enough preheat time helps the stones get hot enough to produce steady steam.

Do steam saunas create a lot of moisture?

Inside the cabin, yes, and that is part of the experience. Outside the sauna, moisture is usually limited and mainly escapes when the door is opened. Standard room ventilation, such as a window or extractor fan, is normally enough to manage it.

Where can a steam sauna be installed?

Steam saunas can be fitted in indoor areas such as home gyms, utility rooms, larger bathrooms, or dedicated wellness spaces. Outdoor-rated models can also be installed in gardens, on patios, or in sheltered outdoor areas. Always check whether the model is intended for indoor or outdoor use.

Are steam saunas safe to use?

Steam saunas are commonly used at home and in commercial settings. It is important to stay hydrated, avoid alcohol before use, and leave the sauna if you start to feel unwell. Anyone who is pregnant or has a medical condition, particularly heart-related issues, should speak to a healthcare professional first.

How often should I use a steam sauna?

Many people use a steam sauna three to five times each week. Beginners often start with shorter sessions of around 8 to 12 minutes, then gradually increase the time as they become more comfortable with the heat.

Do steam saunas need much maintenance?

Maintenance is generally simple. Wipe the benches after use, leave the door open so the cabin can dry, and occasionally check, clean, or reposition the stones in line with the manufacturer’s guidance. If the sauna is installed outside, exterior wood treatment may also be needed.

What is the difference between a steam sauna and an infrared sauna?

A steam sauna heats the air and adds humidity to create a traditional high-heat environment. An infrared sauna warms the body more directly while keeping the air temperature lower. The right choice depends on whether you prefer a hotter, classic sauna feel or a gentler style of heat.

Can any sauna be installed outdoors?

No. A sauna should only be placed outside if it has been built and rated for outdoor use. Outdoor models are made with features such as treated timber, stronger panel construction, and materials designed to cope with moisture and changing weather. Indoor saunas are not made for these conditions and may warp, leak, or develop electrical issues if used outside.

Does an outdoor sauna need extra cover or shelter?

A built-in roof gives the sauna a basic level of protection, but extra shelter can help a lot. Positioning it beneath a canopy or in a more protected part of the garden can improve its resistance to the elements and support longer-lasting performance. Features such as a roof overhang or cover kit can also help reduce direct exposure to rain and lower maintenance over time.

What sort of base does an outdoor sauna need?

An outdoor sauna should be installed on a firm, level, and well-drained surface. Common options include a concrete base, paving slabs, decking, or compacted gravel supported by a solid frame. Uneven ground or direct placement on soil should be avoided, as this can lead to stability issues and may affect how the door and structure sit over time.

Does cold weather impact the performance of an outdoor sauna?

It can. In lower temperatures, especially under 5°C, the sauna may take longer to reach its full operating heat. That said, outdoor saunas are designed to be used all year round. Windy or exposed locations can make heating less efficient, so a more sheltered position is often the better choice for comfort and performance.

Is the electrical setup different for an outdoor sauna?

Yes, outdoor installations need to be handled differently from indoor ones. Cabling must be suitable for external use, and the setup should include RCD protection and weather-resistant electrical components. Installation should always be completed by a qualified electrician. The exact requirements will depend on the model, heater type, and power rating.

Do outdoor saunas still need ventilation?

Yes, proper airflow is still important. Leaving some space around the sauna helps moisture escape and allows the structure to dry naturally. Internal vents also help manage airflow during use and support drying after each session, which helps maintain the cabin in good condition.

How much upkeep does an outdoor sauna need?

Outdoor saunas benefit from occasional exterior treatment, such as a wood protector or sealant, to help defend against the weather. It is also worth keeping the surrounding area clear of leaves, debris, and pooled water. Inside the sauna, maintenance is usually simple and involves wiping benches, cleaning any glass, and leaving the door open after use so the cabin can dry out.

Can an outdoor sauna be installed on decking?

Yes, as long as the decking is strong enough, level, and allows good airflow underneath. Hardwood and composite decking are often suitable options. It is also important to make sure water drains away properly rather than collecting beneath the sauna.

Can rain damage an outdoor sauna?

Outdoor saunas are designed to cope with normal exposure to moisture, but constant heavy rain, poor drainage, or standing water can still shorten the life of the exterior over time. Keeping the wood protected and choosing a more sheltered position can make a big difference to long-term durability.

Can an outdoor sauna be placed inside a summerhouse or garden room?

Yes, that is a popular option for some customers. Installing an outdoor sauna inside a garden room or summerhouse can provide extra protection from the weather and may also help with heat-up times. The space still needs to be dry, well ventilated, and suitable for the model’s electrical setup.