304 Gallons. Under Two Hours. Zero Electricity. The Right-Sized Wood-Fired Hot Tub for Most Backyards.
The SaunaLife Soak-Series Model S4 Wood-Fired Hot Tub delivers the same off-grid, eco-friendly wood-burning experience as SaunaLife's larger S6 models in a more accessible 79-inch diameter footprint — holding over 304 gallons of water and comfortably seating up to 6 bathers. Constructed from Thermo-Spruce, which lasts up to twice as long as cedar with superior thermal resistance to retain heat, the S4's 1.65-inch thick tub surround is finished in black for a sleek, modern exterior. Inside, a thick, dark grey contoured fiberglass lining provides enhanced bather comfort against the tub walls. The stainless steel wood-burning heater uses dual heat compartments for unmatched efficiency, bringing water to ideal soaking temperatures — up to 106°F — in under two hours, with a polished stainless steel chimney and protective cap for safe, rapid heat-up. The S4 arrives fully assembled, requires no electrical connection whatsoever, and includes matching Thermo-Spruce steps for easy access, an extra-thick steel-reinforced foam cover with a dark grey marine-grade vinyl exterior that folds for easy removal and storage, and an integrated drainage tap for simple maintenance. Just position it, fill it, light the stove, and soak — luxury wood-fired bathing without a single utility bill.
Key Specifications
- Series: Soak-Series
- Model: S4
- Type: Wood-burning outdoor hot tub — no electricity required
- Capacity: Up to 6 bathers
- Water Capacity: 304 gallons
- Exterior Dimensions: 79 in diameter × 37 in high
- Interior Dimensions: 71 in diameter × 33 in deep
- Tub Surround: 1.65 in thick Thermo-Spruce, painted black
- Interior Lining: Thick, dark grey contoured fiberglass — enhanced bather comfort
- Heater: 304 stainless steel wood-burning heater — dual heat compartments
- Heat-Up Time: Under 2 hours
- Maximum Temperature: 106°F
- Chimney: Polished stainless steel with protective cap
- Stove Dimensions: 19.8 in D × 11.8 in W × 13.1 in H
- Chimney Dimensions: 4.7 in diameter × 95 in H
- Maximum Wood Length: 16 in
- Access: Matching Thermo-Spruce wood steps
- Cover: Extra-thick steel-reinforced foam, folding design, dark grey marine-grade vinyl exterior
- Drainage: Integrated drainage tap
- Product Weight (filled): 3,064 lbs
- Shipping Dimensions: 91 in L × 46 in W × 87 in H
- Shipping Weight: 595 lbs
- Assembly: Fully assembled — ready to fill and fire
- Electrical Requirement: None — fully off-grid compatible
- Use: Outdoor
- Warranty: SaunaLife Limited Lifetime Warranty (residential use)
- Origin: Designed by SaunaLife, handcrafted in Northern Europe
Who This Is For
The S4 is built for homeowners who want the SaunaLife wood-fired hot tub experience — no electricity, no utility hookup, fully assembled on arrival — in a more compact 79-inch footprint than the flagship S6 models. It suits families and small groups of up to 6, buyers with limited patio or deck space who still want a genuine soaking capacity of 304 gallons, off-grid and rural property owners, and design-conscious homeowners drawn to the modern black Thermo-Spruce exterior paired with dark grey fiberglass and vinyl detailing.
Frequently Asked Questions
Q: How does the S4 compare to the S6B and S6N?
A: The S4 is the more compact model in the Soak-Series — 79-inch diameter and 304-gallon capacity versus the S6B/S6N's 89-inch diameter and 436+ gallon capacity, seating up to 6 bathers versus 7. The S4's surround is painted black as standard, while the S6B offers a black finish and the S6N offers a natural Thermo-Spruce finish as separate model options. All three share the same dual-chamber stainless steel wood-burning heater technology, no-electricity operation, and fully assembled delivery.
Q: Does it really require zero electricity?
A: Yes — the S4 is entirely wood-fired, with the 304 stainless steel heater's dual heat compartments driving water circulation through natural convection. No pumps, motors, or electrical connections are needed, making it fully compatible with off-grid properties and locations without accessible electrical infrastructure.
Q: How long does it take to heat up, and what temperature can it reach?
A: The S4's dual-compartment stainless steel heater brings water to ideal soaking temperature in under 2 hours, with a maximum temperature of 106°F. The polished stainless steel chimney with protective cap ensures safe, efficient combustion and rapid heat response.
Q: What is included with the S4?
A: The S4 arrives fully assembled and includes matching Thermo-Spruce steps for access, an extra-thick steel-reinforced foam cover with dark grey marine-grade vinyl exterior (folds for easy removal and storage), integrated drainage with a tap, a polished stainless steel chimney, and a chimney cap.
Q: What foundation does the S4 require?
A: A flat, level, stable surface capable of supporting the tub's filled weight of approximately 3,064 lbs. Concrete pads, compacted gravel, or reinforced decking are appropriate foundation options. The surface must be completely level for proper stove operation and even weight distribution.
Q: Can the S4 be paired with a sauna for contrast therapy?
A: Yes — the S4 is an ideal companion to any sauna or barrel sauna in the SaunaLife lineup, or to the RAIN-Series R3 outdoor shower for a complete rinse-and-soak circuit. Alternating between sauna heat and the S4's wood-fired warm soak (or following with a cold plunge) creates a full contrast therapy routine using entirely off-grid equipment.
