Finnleo Designer SL2 Sauna Heater

Finnleo Designer SL2 Sauna Heater Series

The Finnleo Designer SL2 is a wall-mounted electric sauna heater engineered for authentic Finnish heat in home and light-commercial saunas. Built by Sauna360 in Cokato, Minnesota, the Designer SL2 is offered in four configurations to match nearly any room size and electrical setup: 4.5 kW (240V 1PH), 6.0 kW (240V 1PH), 8.0 kW (240V 1PH), and 8.0 kW (208V 3PH). Each unit is engineered to hold a generous bed of sauna rocks in direct contact with the heating elements, delivering fast heat-up times, stable temperatures, and the soft, even steam that defines a true Finnish sauna experience.

Key Features

• Space-saving wall-mounted design that frees up bench and floor space
• Available in four power configurations: 4.5 kW, 6.0 kW, and 8.0 kW (single-phase), plus 8.0 kW (three-phase)
• Sized for saunas ranging from approximately 100 to 425 cubic feet, depending on kW selected
• Rocks included on every configuration, pre-sized for optimal heat retention and steam quality
• Compatible with the SaunaLogic2 control system, including Wi-Fi enabled operation via mobile app
• Optional BioWater Technique water tank available on 6.0 kW and 8.0 kW models for a gentle steam/humidity boost
• Available as Heater Only or as a bundled package with SaunaLogic2 controls
• ETL listed and safety-tested for residential and light-commercial use in North America
• Backed by Finnleo's factory warranty and dealer support

Power & Sizing Options

Choosing the right Designer SL2 output comes down to room volume and available electrical service:

• 4.5 kW (240V, 1PH): Sized for smaller saunas, typically in the 100 to 200 cubic foot range. Ideal for compact home installations where space and circuit capacity are limited.
• 6.0 kW (240V, 1PH): Suited to mid-sized saunas, generally 150 to 300 cubic feet. The most popular output for standard home saunas, balancing heat-up speed with efficient power draw. Compatible with the optional BioWater Technique tank.
• 8.0 kW (240V, 1PH): Built for larger single-phase installations, covering roughly 300 to 425 cubic feet. Delivers faster heat recovery for bigger rooms and higher-traffic saunas. Compatible with the optional BioWater Technique tank.
• 8.0 kW (208V, 3PH): The three-phase version of the 8.0 kW heater, designed for facilities and homes with 208V three-phase service, commonly found in commercial buildings, health clubs, spas, and multi-unit residential settings. Requires a dedicated contactor (CB) box, included in bundled configurations, to manage the three-phase load safely. Also compatible with the optional BioWater Technique tank.

All four models share the same wall-mounted housing, rock capacity philosophy, and control compatibility — the difference lies strictly in heat output, amperage draw, and (for the 8.0 kW 3PH unit) phase configuration.

Construction & Build Quality

The Designer SL2 features a rugged steel housing designed for continuous use in the high-heat, high-humidity sauna environment. Its compact, low-profile wall-mounted frame is built to sit close to the wall, maximizing usable bench and floor space compared to freestanding heaters. The open rock chamber design allows air to circulate directly through the rock bed, so heat radiates evenly across the room rather than concentrating near the heater. Every Designer SL2 heater is safety-tested and ETL listed for the North American market, reflecting Finnleo's long-standing manufacturing standards out of its Cokato, Minnesota facility.

Rocks Included

Every Designer SL2 configuration, regardless of kW rating or phase, ships with a full set of sauna rocks sized specifically for that heater's rock chamber. The rocks are placed in direct contact with the heating elements to produce the dense, even heat and soft steam associated with traditional Finnish sauna bathing. Finnleo recommends replacing the rocks approximately every one to three years, or sooner with frequent use, to maintain optimal heat transfer and steam quality.

SaunaLogic2 Control System

Every Designer SL2 heater is compatible with Finnleo's SaunaLogic2 (SL2) control system, available in Wi-Fi and non-Wi-Fi versions. The Wi-Fi enabled control connects to the free SaunaLogic2 mobile app, allowing users to:

• Power on the sauna remotely and schedule start times so the room is ready on arrival
• Monitor and adjust temperature and session duration from a smartphone or tablet
• Integrate optional mood lighting for a customizable ambiance
• Pair with an optional Bluetooth soundbar for audio during sauna sessions

Single-phase models (4.5 kW, 6.0 kW, and 8.0 kW 1PH) run directly from the SaunaLogic2 control without additional hardware. The 8.0 kW three-phase model requires the SaunaLogic2 control paired with a contactor (CB) box to safely manage three-phase current — this component is included in bundled configurations for that model.

Optional BioWater Technique Tank

The 6.0 kW, 8.0 kW (1PH), and 8.0 kW (3PH) Designer SL2 heaters support Finnleo's optional BioWater Technique water tank accessory. This add-on introduces a controlled trickle of water onto the heated rocks, producing a gentle, continuous steam effect that raises humidity for a softer, more soothing heat than dry sauna alone — without the intensity of a full steam bath. The 4.5 kW model does not support this option.

What's Included

• Designer SL2 wall-mounted heater (4.5 kW, 6.0 kW, 8.0 kW 1PH, or 8.0 kW 3PH, per selection)
• Full set of sauna rocks, sized for the selected heater's rock chamber
• SaunaLogic2 control panel (Wi-Fi or non-Wi-Fi, based on selected package)
• Contactor (CB) box — included with bundled 8.0 kW (208V 3PH) configurations
• Manufacturer installation and wiring guide
• Finnleo factory warranty coverage

Note: Selecting "Heater Only" excludes the SaunaLogic2 control and CB box; these can be purchased separately or added as a bundled package option.

Installation Notes

All Designer SL2 heaters are intended for professional installation by a licensed electrician, in accordance with local electrical codes. The 240V single-phase models (4.5, 6.0, and 8.0 kW) run on standard single-phase residential circuits sized to the unit's amperage draw. The 208V three-phase 8.0 kW model requires three-phase service, typically found in commercial buildings, spas, and health clubs, along with its accompanying contactor box for safe operation. Always confirm circuit sizing, breaker requirements, and room cubic footage with a qualified installer before purchase.

Why Buy Finnleo From Us

Finnleo, manufactured by Sauna360 in Cokato, Minnesota, is one of the most trusted names in authentic Finnish sauna heating. Every heater in the Designer SL2 series is safety-tested and listed for the North American market, and the SaunaLogic2 ecosystem ties your heater, lighting, and audio into a single app-controlled experience. As an authorized Finnleo dealer, we offer full factory warranty coverage, expert help sizing the right heater for your space, and support before and after your purchase. Have a question about fit, voltage, or lead time? Reach out and a sauna specialist will help you spec the right Designer SL2 configuration the first time.