Frequently Asked Questions
How long does it take to heat a wood-fired hot tub?
It depends on the model, the starting water temperature and the weather. SaunaLife rates the S4 to heat its 304 gallons from 40°F to 95°F in 1.5 to 2 hours and lists the 436-gallon S6 at 1.5 to 2 hours; its manuals recommend heating to no more than 105°F and say covering the tub while it heats warms the water faster. Dundalk does not publish a heat-up time for the Starlight. Its instructions say to stop adding wood once the water is about 10°F below your bathing temperature (usually 101–104°F) and let it finish rising on its own; Dundalk says the water drops about 5–10°F overnight and recommends a cover to reduce heat loss.
What wood are these hot tubs made from, and what firewood do they burn?
The Dundalk Starlight has a white cedar skirt, western red cedar backrests and floor, and a 5052 aluminum or white plastic interior. The SaunaLife S4 and S6 have a 1.65-inch Thermo-Spruce surround, a dark grey fiberglass liner and a 304 stainless-steel stove. For fuel, both manufacturers call for dry firewood: SaunaLife limits logs to 13 inches and says to light the fire with a pellet fire starter or lighter fluid rather than paper, which throws sparks and embers, while Dundalk starts the Starlight's fire with crumpled paper, kindling and small dry logs and uses the stove lid as the damper. Never light either stove before the tub is full of water.
Do you need chemicals in a wood-fired hot tub?
Neither manufacturer's instructions for these tubs call for a sanitizer. Dundalk suggests changing the Starlight's water regularly based on how often it is used and the water's condition, and draining and rinsing it when the water turns cloudy, develops an odour or has sat unused; untreated water can go onto the garden or back into a lake or stream only if no chemicals were used. SaunaLife says to shower before soaking, wash the S4 and S6 after each use, and never use chlorine-containing cleaners or chlorine solutions on the tub, which can discolour it. If you plan to use any water treatment, confirm with the manufacturer that it suits your tub's liner first.
What foundation does a hot tub need?
A level surface built for the full filled weight. SaunaLife lists the S4 at 3,064 lb filled. Water weighs about 8.3 lb per gallon, so the water alone is roughly 1,900 lb in the Starlight (233 gallons) and roughly 3,600 lb in the S6 (436 gallons), before the tub and bathers. Whether you use compacted gravel, a concrete pad or a deck, it must be level and able to carry that load; have an existing deck checked by a qualified person first. SaunaLife's instructions call for leveling the tub with a liquid level on the rim and placing the S4 and S6 at least 13 feet from any building for fire safety.
How long does a wood-fired hot tub last?
Service life depends on the liner and tub material, climate, water chemistry, maintenance, and how the tub is stored and covered, so Topture does not quote a universal lifespan. The manufacturers' care steps are the practical guide: SaunaLife says to treat the S4's and S6's wood parts with an exterior wood oil at least once a year, and Dundalk says the Starlight's cedar can be left to weather silver-grey or given a penetrating exterior finish, with a full drain, deep clean and inspection of the heater, chimney and fittings once a year.
Can you use a wood-fired hot tub in winter, and how do you drain it?
Yes, if you follow the manufacturer's winter procedure, because standing water can freeze and break the tub, stove or fittings. SaunaLife says that in winter the S4 and S6 must be drained, tub and stove, after every use, with the drain valve left open, and never before the stove's embers are completely out. For the Starlight, Dundalk says that if the tub won't be used in freezing temperatures you should completely drain the tub, the drain assembly and any other water-holding parts, and keep snow and ice from building up on the cover. The SaunaLife tubs drain through an integrated tap; the Starlight has a drain assembly with a shut-off valve and an optional garden-hose connector.
Does a wood-fired hot tub need electricity?
No. The Dundalk Starlight and the SaunaLife S4 and S6 all heat with a wood stove and need no electrical connection; you need firewood and a water source for filling. None is currently offered with an electric or dual-fuel heater at Topture. If you are considering an electric tub, its breaker size, conductor size and circuit configuration must be taken from the installation manual for that specific model.
What is the difference between a wood-fired hot tub and a regular hot tub?
A wood-fired hot tub heats its water with a wood-burning stove, either inside the tub or mounted on its side and fired from outside, and needs no electrical connection. A conventional acrylic spa uses an electric heater, circulation and jet pumps and a control system. Traditional wood-fired tubs use a simpler heating system than pump- and jet-driven acrylic spas, so the ownership and maintenance profile is different: you light and tend a fire for each soak and change the water by draining and refilling, rather than relying on pumps and filtration between uses. Running costs depend on your firewood versus your electricity rate and how often you soak.
How much water does a wood-fired hot tub hold, and how many people does it seat?
It depends on the model. The Dundalk Starlight holds 233 gallons (885 L) in a rectangular interior 66-3/4 by 33 inches and 24-1/4 inches deep; Dundalk does not publish a seating number. The SaunaLife S4 holds 304 gallons and seats up to 6 (71-inch interior diameter, 33 inches deep), and the S6 holds 436 gallons and seats up to 7 (80.7-inch interior diameter, 35.4 inches deep). SaunaLife's instructions fill the tub to about 6 inches below the top. More water means more weight on the foundation and more firewood to heat it, so size the tub to how many people will actually soak.
Are wood-fired hot tubs hard to maintain?
Maintenance centres on the water, the stove and the wood, since these tubs have no jets, circulation pumps or electronics. Before each use, check the water is clean and the level is high enough before lighting the stove; SaunaLife fills to about 4 inches over the section above the stove. Remove ash only once it is completely cold, and put the cover back on to keep out debris. SaunaLife says to wash the S4 and S6 after each use with household detergent and a soft cloth, never chlorine solutions or abrasives, and to oil the wood parts at least once a year. Dundalk says to clean the Starlight's lined interior with warm water, mild soap and a soft cloth, inspect the heater, chimney and drain fittings regularly, and drain and deep-clean the tub once a year.
What comes with a wood-fired hot tub from Topture?
It depends on the model. The SaunaLife S4 and S6 arrive fully assembled apart from the chimney, with steps, an insulated folding cover, an integrated drain tap and a polished stainless-steel chimney with cap. The Dundalk Starlight arrives as the aluminum- or plastic-lined tub with its internal wood stove and chimney and Dundalk's setup manual; setup means fitting the drain valve, sliding the chimney into the stove and installing the backrests, and its roll-up cover is a separate option. With any of them you supply dry firewood and water.
How is a wood-fired hot tub delivered?
By LTL freight to the curb or the end of the driveway, on a delivery appointment, and an adult signs the Bill of Lading. The Dundalk Starlight ships in a crate 86 by 45 by 34 inches weighing 701 lb, and the customer offloads it, usually with a forklift on fork extensions or by collecting it from the local terminal with a tilt-bed tow truck. The SaunaLife S4 (595 lb shipping weight) and S6 (728 lb) ship palletized, fully assembled apart from the chimney. The Starlight ships free within the contiguous U.S.; SaunaLife tubs carry a freight charge shown on each product page.
What warranty comes with these hot tubs?
The manufacturer's warranty applies, subject to its terms; Topture helps with troubleshooting and warranty coordination. Dundalk covers the products it designs and manufactures, including the Starlight, with a 5-year residential limited warranty against defects in materials and workmanship; it covers replacement parts, not labor or installation. SaunaLife's S4 and S6 manuals give 2 years for private customers and 6 months for commercial use.