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HUUM Steel Mini Series

The HUUM Steel Mini is the heater for anyone who wants full sauna performance without giving up half the room to get it. It comes only in 3.5 kW, covers rooms up to 5 m³, and mounts flush with the wall to keep bench space free and the room uncluttered. Its clean Nordic design lets it blend seamlessly into a variety of sauna interiors while saving space.

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Technical Specifications

Specification

3.5 kW

Output

3.5 kW

Voltage

230V single phase

Suitable room volume

Up to ~5m³

Stone capacity

15 kg

IP rating

IP34

Housing material

Stainless steel

Mounting

Wall-mount bracket

Country of origin

Estonia

The Steel Mini requires a dedicated electrical circuit and installation by a qualified electrician. The IP34 rating means the heater is protected against splash water from any direction, which is appropriate for a sauna environment.

Is the Steel Mini the Right Fit for Your Room?

The 3.5 kW Steel Mini is designed for sauna rooms up to approximately 5 m³. In practical terms, this means a compact two-person sauna with a standard ceiling height and good insulation.

However, keep in mind that certain design features increase a sauna’s heat requirements. For instance, large glass surfaces, glass doors, and higher ceilings can make the room feel larger, which can reduce heating performance if the heater is undersized.

Before choosing the Steel Mini:

  • Measure the internal volume of your sauna room (length × width × ceiling height in metres).
  • Add 20% to that figure if you have a glass wall or a ceiling above 2.2m.
  • If the adjusted figure exceeds 5m³, step up to the HUUM Steel range rather than pushing the Mini beyond its designed output.

If you are unsure, our sauna experts can advise on the right model for your specific dimensions.

Controls and Connectivity

The Steel Mini works with the UKU Wi-Fi controller, which lets you preheat your sauna remotely via the HUUM app on iOS or Android. Set a start time before you leave work, adjust the target temperature from your sofa, or check the heater has switched off — all from your phone. The UKU supports a temperature range of 40°C to 110°C and includes a built-in timer.

The controller is sold separately, so you choose the level of connectivity that suits you. If you prefer a physical control panel without an app dependency, the UKU Local offers the same temperature and timer controls via a wall-mounted unit.

Your electrician wires the controller and heater at the same time, so it makes sense to order both together rather than retrofitting the controller later.

Installation and Safety Clearances

The Steel Mini requires installation by a qualified electrician on a dedicated 230V single-phase circuit. Sauna installations have specific requirements that a general domestic electrician may not encounter regularly, so experience with sauna wiring makes a real difference.

Loading the stones

Use rounded igneous rock, such as granite, olivine diabase, or HUUM’s own sauna stones. When you get your heater, stack the stones loosely around the heating elements rather than packing them tightly, to allow airflow and even heat distribution. Avoid sedimentary or layered rock, which can crack under repeated heating cycles.

Ready to Choose Your Steel Mini?

The Steel Mini is the right heater for a compact home sauna where the room size is fixed, but the build quality does not have to be. Whether you are starting a new installation or replacing a heater that is no longer keeping up, the decision comes down to your room’s cubic volume and how much glass or ceiling height you have to work with. Browse the full collection or get in touch, and we will help you land on the right configuration.

Frequently Asked Questions

Does the HUUM Steel Mini come with a controller?
No. The controller is sold separately. You can choose the UKU Wi-Fi controller for remote preheat via the HUUM app, or the UKU Local for straightforward wall-panel control without Wi-Fi. Both are compatible with the Steel Mini.
How long does the Steel Mini take to reach temperature?
Typically, warm-up takes 30 to 45 minutes, depending on room volume, insulation quality, and your target temperature. A well-insulated 4 m³ room will reach 80 °C in about 30 minutes under normal conditions.
What sauna stones should I use?
Use rounded igneous rock such as granite, olivine diabase, or HUUM’s own sauna stones.
Is the controller included in the price?
The Steel Mini is priced without a controller. The UKU Wi-Fi controller and UKU Local are available separately. Contact Heracles Wellness to confirm current bundle options.
What warranty does the Steel Mini carry?
HUUM provides a standard 2-year warranty. The warranty is valid only if a qualified electrician installs the sauna per the HUUM installation manual and you use compatible sauna stones.

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