Wood Fired Hot Tubs

How Wood Fired Hot Tubs Work

A wood fired hot tub heats water using a wood-burning stove instead of an electric heater. There's no electricity involved, no plumbing hookup, and no gas line. You fill the tub with a garden hose, build a fire in the stove, and wait for the water to come up to temperature. It's about as simple as outdoor soaking gets.

There are two main stove designs. An internal (submersible) stove sits inside the tub shell. Water surrounds the firebox directly, so heat transfer is fast and efficient. The Dundalk Starlight uses this design, with the stove lid doubling as the damper; Dundalk describes the internal heater as a deliberate choice for heat and safety. An external stove sits outside the tub and connects through inlet and outlet ports. As water heats inside the stove, it naturally rises and circulates back into the tub through a process called thermosiphoning, with no pump needed. The SaunaLife S4 and S6 use a 304 stainless-steel stove mounted on the side of the tub with its firebox door on the outside; SaunaLife says it draws cooler water in through a lower channel and returns it through an upper channel.

Heat-up time depends on the tub's volume, the starting water temperature, the weather and your firewood, so compare each manufacturer's own figure. SaunaLife rates the S4 to heat 304 gallons from 40°F to 95°F in 1.5 to 2 hours and the 436-gallon S6 in 1.5 to 2 hours, recommends heating to no more than 105°F, and says 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 when the water is about 10°F below your bathing temperature (usually 101–104°F) and let it finish rising on its own.

Wood Fired Hot Tubs Compared

The three wood fired tubs Topture carries differ in stove position, size and published heat-up data. All figures are the manufacturers' own; none of the three needs electricity.

How to Choose the Right Wood Fired Hot Tub

Construction materials matter

The tub's material affects durability, maintenance, and how long it'll last. The Dundalk Starlight has a white cedar skirt with western red cedar backrests and floor, and your choice of a 5052 aluminum or a white plastic interior; Dundalk's care guidance for lined interiors is warm water, mild soap and a soft cloth. The SaunaLife S4 and S6 pair a 1.65-inch Thermo-Spruce surround, in a natural or black finish, with a dark grey fiberglass liner, giving them a clean barrel aesthetic that looks right at home next to an outdoor sauna.

Capacity and who's soaking

Think about how you'll actually use the tub. SaunaLife rates the S4 for up to six bathers and the S6 for up to seven, and its manuals say not to exceed the recommended number of users. Dundalk does not publish a seating number for the Starlight, a rectangular cedar tub with a 66-3/4 by 33 inch interior and a backrest at each end, so compare that with the SaunaLife tubs' 71-inch and 80.7-inch interior diameters. If you're planning backyard gatherings, the round SaunaLife tubs have the larger interiors.

Stove type: internal vs. external

All three tubs keep the fire inside a closed stove with its own chimney: internal on the Starlight, mounted on the side and fired from outside on the SaunaLife S4 and S6. Both manufacturers warn never to light the stove before the tub is full of water, and SaunaLife says never to leave it unattended while heating. Firewood rules differ: SaunaLife calls for dry wood in logs no longer than 13 inches, lit with a pellet fire starter or lighter fluid rather than paper, while Dundalk starts the Starlight's fire with crumpled paper, kindling and small dry logs and uses the stove lid as the damper.

Off-grid or backyard?

All three tubs here are wood-fired only: no electrical hookup, no dedicated circuit, no electrician visit. That makes them a strong choice for cabins, rural properties, or anywhere running power would be expensive or impractical. In a backyard, check the site first: SaunaLife requires the S4 and S6 to stand at least 13 feet from any building, and the Starlight's chimney reaches 110 inches above the ground, so keep it clear of branches and eaves. For the broader decision, including how wood-fired tubs compare with jetted acrylic spas and where to buy one, see the full hot tub collection.

Brands We Carry

Dundalk Leisurecraft — The Starlight is handcrafted in Ontario, Canada, with a white cedar skirt and western red cedar backrests and floor, and belongs to Dundalk's Canadian Timber Collection alongside the barrel and cabin saunas in their cedar sauna line. The Starlight comes with options for an aluminum or plastic interior liner, plus an optional roll-up cover for heat retention. Dundalk says its cedar can be left unfinished to weather to silver-grey without reducing its natural durability, or kept at its original colour with a penetrating exterior finish.

SaunaLife — Known for their barrel saunas and cube saunas, SaunaLife makes the S4 (up to six bathers) and S6 (up to seven) from Thermo-Spruce with a fiberglass liner, engineered and crafted in Northern Europe. Both come in natural or black, arrive fully assembled apart from the chimney, and pair naturally with SaunaLife's outdoor sauna models if you're building out a full backyard setup. SaunaLife tubs carry a freight charge shown on each product page.

What's Included and What You'll Need

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 tub with its internal stove and chimney; setup means fitting the drain valve, sliding the chimney into the stove and installing the backrests. You provide dry firewood, a hose or other water source, and a level base built for the filled weight: SaunaLife lists the S4 at 3,064 lb filled, and the water alone in the 436-gallon S6 weighs roughly 3,600 lb. Footprints are 83-3/4 by 35-3/4 inches for the Starlight, and 79 and 89 inches in diameter for the S4 and S6, plus room for steps. No electrical work needed.

A roll-up cover is available as an add-on for the Dundalk Starlight; Dundalk recommends a cover to reduce heat loss at night or when the tub isn't in use, and SaunaLife says covering the tub while heating warms the water faster. These tubs have no circulation pump or filter, so the water is changed by draining and refilling: Dundalk suggests changing it regularly based on use and water condition, and draining and rinsing when it turns cloudy, develops an odour or has sat unused. On the SaunaLife tubs, don't open the drain until the stove's embers are completely out.

Water care: Neither manufacturer's instructions for these tubs call for a sanitizer. SaunaLife says to shower before soaking, wash the S4 and S6 after each use with household detergent and a soft cloth, and never use chlorine-containing cleaners or chlorine solutions on the tub, which can discolour it; ash that gets into the water can be lifted out with a kitchen sieve. Dundalk says to avoid bleach, abrasive pads and harsh chemical cleaners on the Starlight, and that untreated water can go onto the garden or back into a lake or stream only if no chemicals were used. If you plan to use any water treatment, confirm with the manufacturer that it suits your tub first.

Winter: SaunaLife says that in winter the S4 and S6 must be drained, tub and stove, after every use, with the drain valve left open, because freezing water can break the tub, stove or valve. 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.

Pair your wood fired tub with an outdoor barrel sauna for a full backyard wellness setup, or add a cold plunge for hot-and-cold soaking. If you're interested in wood-burning sauna stoves, the same firewood that heats your tub works for your sauna. And if you need accessories like buckets, ladles, or covers, we carry those too.