How to Choose the Best Sauna Heater: A Complete Buyer’s Guide

Selecting the right sauna heater is essential for creating an authentic, enjoyable, safe and efficient sauna experience. Whether you’re seeking the rustic charm of a wood-burning heater or the convenience of a modern electric model with smart control options, this guide will help you navigate the key considerations, ensuring you choose a heater that aligns with your sauna’s specifications and your personal preferences.

Choosing the right sauna heater depends on the size of your sauna, the sauna's specifications, location and your personal preference. Image provided by HUUM.

Determining the Appropriate Heater Size

Calculate Your Sauna’s Volume

Begin by calculating the volume of the sauna to determine the necessary output of your heater. Often, the basic rule is that 1 kW of heater power is required for every 1 m³ of sauna volume. However, the power of your sauna heater must be matched to the internal computational volume of your sauna. This volume is not just the physical dimensions (length x width x height) - it also accounts for materials and design features that influence heat loss. This includes uninsulated surfaces, such as windows and glass doors.

Volume Adjustments for:

Glass Surfaces: Add 1m³ for every 1m² of glass.
Uninsulated Walls: Add 1.5m³ for each square metre of uninsulated surfaces.

These adjustments account for heat loss through materials that are less efficient at retaining heat.

A slightly oversized heater is preferable to one that is underpowered, as you can moderate the output of a larger unit, but an underpowered unit will struggle to heat the space effectively.

Typical Power vs. Sauna Volume Guidelines:

Model Power Output	4.5 kW	6/6.8 kW	9 kW	10.5 kW
Capacity of the sauna	4-7m³	5–8/9 m³	8–14 m³	10–18 m³

Note: Always consult the manufacturer’s specifications for each individual model for precise recommendations before making a purchase.

You can also use our sauna heating calculator for guidance on heater sizing.

IKI Electric Sauna Heater in a Finnmark Bespoke Home Sauna

Choose a sauna heater that is powerful enough for the size of your sauna. Uninsulated areas, such as windows, add to the internal computational volume of the space.

Electric vs Wood-Burning Sauna Heaters

Choosing between electric and wood-burning sauna heaters depends on your desired experience, installation setting, and lifestyle. Electric heaters offer convenience, precise control, and are ideal for residential and urban settings, while wood-burning heaters deliver a traditional, off-grid experience with atmospheric charm.

Electric Sauna Heaters

Electric sauna heaters are a popular choice for UK installations due to their ease of use, precise control, and minimal maintenance.

Key Advantages:

User-Friendly Operation: Simple startup and shutdown; programmable timers for scheduled use.
Flexible Control Options: Choose from built-in, external, or smart Wi-Fi controls for maximum flexibility.
Clean and Efficient: No flue or firewood required; ideal for indoor or residential settings.

Narvi Velvet Electric Sauna Heater in a Finnmark Bespoke Home Sauna Installation

Electric sauna heaters are popular in home saunas as they provide convenience and often smaller safety distances to combustible materials, allowing for installations in smaller spaces. Narvi Velvet electric sauna heater mounted into a floating bench system.

Understanding Electrical Requirements

Single-Phase vs. Three-Phase Power

In the UK, most residential properties have a single-phase power supply. Heaters up to 9kW can typically operate on single-phase power, but it’s essential to verify compatibility, as there are exceptions to this. Heaters exceeding 9kW often require a three-phase supply, which is more common in commercial settings.

Dedicated Electrical Circuits

Electric sauna heaters demand power and should be connected to dedicated circuits. Always refer to the heater installation manual and consult a qualified electrician to assess your home’s electrical capacity and to perform the installation safely.

Control Units and Thermostats

Modern electric sauna heaters often come with integrated control units and thermostats, allowing you to set and maintain desired temperatures and program heating schedules. Some models offer Wi-Fi connectivity, enabling remote control via smartphone apps. Ensure the control system is compatible with your heater and meets your usability preferences. Read more about how to choose the best controller for your sauna.

UKU Wi-Fi Glass Black Electric Sauna Heater Controller

Modern electric sauna heaters often come with a variety of control options from manual dials to Wi-Fi control systems. UKU Wi-Fi glass black in the image.

Wood-Burning Sauna Heaters

For those seeking the traditional sauna experience, wood-burning heaters offer an unmatched atmosphere.

Key Considerations:

Authentic Feel: Crackling fire and soft steam recreate the true Finnish and Nordic sauna experience.
Off-Grid Friendly: No electricity required - ideal for rural and wilderness locations as well as zones that aren't smoke-free.
Installation Requirements: Must be fitted with a flue kit and often require additional heat shielding. We always advise consulting a HETAS-certified professional for a safe installation.

Maintenance & Operation:

Requires regular firewood loading and ash removal.
Flue and chimney should be inspected periodically for safe operation.

Special Features:

Tunnel Models: Allow external firewood loading, maintaining a clean sauna interior.
Water Tank Models: Heat water for washing, perfect for remote or off-grid use.

Sauna Heater Installation Considerations

Safety Distances

Adhering to manufacturer-specified safety distances between the heater and combustible materials is vital to prevent fire hazards. These distances vary by model and installation type (wall-mounted vs. floor-standing). In most cases, wood-burning models require larger safety distances and additional heat shielding if installed in a smaller sauna.

Heater Placement

Strategic placement of the heater ensures even heat distribution:

Wall-Mounted Heaters: Ideal for smaller saunas to save space.
Floor-Standing Heaters: Suitable for larger saunas, offering higher outputs and options for mounting into the sauna benching.

Note: Always follow the manufacturer’s guidelines for installation and positioning.

Additional Features to Consider

Design Aesthetics: Choose a heater that complements your sauna’s interior, whether you prefer a traditional or contemporary style.
Stone Capacity & Quality: A higher stone capacity can provide a more consistent and gentle heat, enhancing the sauna experience. Choose high-quality olivine diabase or vulcanite sauna stones designed for sauna heaters. Pouring water over the stones is key to creating the iconic “löyly.” Both wood-burning and electric sauna heaters are designed to handle ladles of water throughout the sauna session.
Heat Shielding: You may want to consider heat shielding particularly for wood-burning sauna heaters to meet minimum safety distances to combustible materials.
Energy Efficiency: Opt for models designed to minimise energy consumption without compromising performance.
Warranty and Support: Consider the manufacturer’s warranty and the availability of customer support services.

Final Considerations When Choosing Your Sauna Heater

Assess Your Sauna’s Specific Needs: Consider size, insulation, uninsulated surfaces, electrics, and usage frequency.

Choose Your Heating Method: Decide between electric or wood-burning based on your lifestyle, installation context, and preferences.

Respect Safety Regulations: Always consult certified professionals (HETAS for wood, electricians for electric) for safe installation.

Consult Professionals: Engage qualified professionals, sauna specialists, and electricians for installation to ensure safety and compliance with UK regulations.

Prioritise Quality and Reliability: Invest in reputable brands known for durability and customer support. Finnmark only offers sauna heaters from market-leading Nordic brands, such as Narvi, HUUM, Helo, Tulikivi and IKI.

Explore Finnmark’s Sauna Heater Range

We offer a carefully curated selection of premium sauna heaters - from elegant electric models to robust wood-burners - all backed with expert advice and UK-based customer service.