The Ultimate Guide to Wood Fired Hot Tubs

What is a wood fired hot tub?

Wood fired hot tubs are what they sound like: hot tubs heated by wood, with no electricity required. They can be used off-grid where power is unavailable, which makes them a natural fit for cabins, cottages and recreational properties. They also work at home, where owners choose them for the look, the experience, the running costs, or the sustainability a conventional spa cannot match. Some can be dual-fueled with electricity or solar, which makes them workable in residential neighborhoods and guest properties too.

Key takeaways

• Off-grid ready. No electricity required, which makes them viable at cabins and remote properties
• A different experience. Silent and jet-free, built around the ritual of fire and water
• Efficient heating. A submerged firebox brings the tub to temperature in a few hours and holds it overnight on very little wood
• Durability. A marine-grade aluminum structure holds water without depending on the wood swelling, and is more hygienic and more recyclable than all-wood or plastic
• Low maintenance. No jets, no internal plumbing, no complex filtration to service, with no UV or ozone needed

Wood fired versus a conventional spa

One distinction before the table, because it trips people up. A conventional acrylic spa and an electrically heated cedar tub are not the same thing. The comparison below is against the acrylic spa most people picture: a moulded shell with banks of jets, multiple pumps and yards of internal plumbing. The AlumiTub Electric is the same tub as the wood fired one with a different heat source, so almost none of the right-hand column applies to it.

Feature	Conventional acrylic spa	Wood fired hot tub
Power source	Electricity, continuous	Wood, renewable
Installation	Professional electrical, and usually a crane	None beyond a flat surface. Rolls into place
Maintenance	Higher. Sanitizer, filters and plumbing you cannot reach	Lower. Fill, use, drain
Sound	Jets and motors	Crackling wood
Servicing	Components sealed inside the cabinet, often in foam	Very little to service
Lifespan	Limited by shell and electronics	Generational, with aluminum and steel

A fuller comparison, covering all three side by side, sits in wood fired hot tubs versus electric spas.

The drawbacks of a conventional spa

Acrylic spas have their place, but the experience is different. They need professional installation and usually a crane on delivery day, they depend on a treatment routine, and they draw power around the clock whether or not anyone is soaking. Their working parts sit sealed inside a cabinet, so reaching a failed component means a service call, and that is usually what decides whether a spa gets repaired or replaced.

A wood fired tub relies on nothing but fire and water. No hum from jets or filters to compete with birdsong or waves. And it can be filled from whatever water is nearby, whether that is a lake, a river, a well or the ocean.

An electrically heated AlumiTub keeps most of that. The same cedar and marine-grade aluminum, a single 30 gpm jet rather than a bank of them, no plumbing loops to keep clean, and the whole heating and filtration system housed in a cedar step against the tub where every part is reachable and replaceable. What it adds is a temperature that is simply there when you want it, set from a touchpad or the Wi-Fi app anywhere between 50 and 104°F, with timer schedules for heating and filtration. The cedar tub that stays hot covers it properly.

Is a wood fired hot tub right for you?

To run one, you chop the wood, light the fire, stir the water to distribute the heat, and feed the fire to hold temperature. If that sounds like a chore rather than a ritual, a wood fired tub is not for you, and the Electric or Hybrid is the better answer in the same tub. If underwater speakers and jets are what you are after, likewise.

If connecting with the outdoors is the point, it offers something no other tub does. Think of the difference between a coffee pod and a slow pour. Both have their place. One rewards the time it takes.

How to heat a wood fired hot tub

Operating one is simple, though it takes practice to land the temperature where you want it. You will need matches, paper, kindling, larger logs, and a way to fill the tub.

Always fill the tub before lighting the fire. Fill to the line marked on the tub, or at least 4 inches above the chimney collar, and keep the water there the entire time the firebox is hot. Firing an empty or part-filled tub warps the firebox and risks fire, structural damage or forceful ejection of the chimney assembly. This is the single most important instruction on this page, and it is the one thing that voids firebox coverage.

AlumiTubs can be filled from a hose, pumped from a lake or river, or filled directly from the ocean. Ocean fills are changed every five to seven days rather than left standing, and the tub is rinsed between fills.

Once full, build the fire at the rear of the firebox below the chimney: crumpled paper, then kindling, then small dry logs. The wood needs to be genuinely dry, which is where most first-time disappointment comes from.

Light it and keep the stove lid open about 4 inches for airflow while the fire is establishing. Add larger pieces as it catches, but never load wood above the internal pipes.

Stop adding wood at 95°F and let the water climb the rest of the way to 101 to 104°F on its own. An AlumiTub rarely struggles to get hot. The more common problem is overshooting. If it does run hot, add cold water away from the stove and stir with a paddle.

Because the stove is submerged, heat transfers straight into the water rather than radiating outward, which is why it is more efficient than an external firebox.

Once at temperature, an armful of wood a day holds it. With the insulation and lid in place, a wood fired tub loses only two to three degrees overnight, which is why the second evening in a row takes a small maintenance burn rather than a full heat-up. Never drain below the fill line until the firebox has fully cooled.

Sunday morning 8am. Hadn't added a log for 11 hours and it was still 103.

Marc Young, Bowyer Island BC

How long does it take to heat?

Between 1.5 and 5 hours depending on size and conditions: around two hours for the Small, three for the Standard, and about five for the Large. Reheating an already-warm tub is much faster than starting from cold.

What affects it:

• Water and air temperature. A January fill from a cold well behaves differently from a summer hose
• Firewood. Dry, seasoned wood burns hotter and cleaner
• Stove design. Submerged fireboxes outperform external ones
• Insulation. Lids and side insulation stop heat leaving as fast as you add it
• Water volume. 315 gallons on the Small, 420 on the Standard, 650 on the Large
• Circulation. Stirring distributes heat evenly rather than letting it stratify

An Electric works the other way round. It takes up to fourteen hours from a cold fill, at roughly three degrees an hour, so it is designed to hold a temperature or run on a schedule rather than be heated on demand. There is no overnight drop to plan around: the water is at the temperature you set it to. On a Hybrid you get both, and running the fire alongside the element is faster than either alone.

Traditional cedar tubs have no insulation layer, so heat loss is higher throughout. Use the lid whenever the tub is not in use, and place the floating insulation on the water surface beneath it.

I can't believe the tub stays so hot. It heats so easily and the next morning when we went to use it, it had only dropped 3 degrees. It's well insulated and well made.

Jess Krutz

Winter use and winterizing

Letting a tub freeze will damage it, and can create a hazard the next time it is used.

Winterizing an AlumiTub can be as simple as draining and wiping it out before you leave, once the firebox has cooled. If water is scarce, or the lake you draw from is frozen, you can leave it filled provided you have power for a stock tank heater or pond de-icer. Check its rated volume against your tub size.

If the tub is attended and you want to use it through winter, heating it periodically is enough to hold the water above freezing. AlumiTubs have been tested heating on wood in ambient conditions as cold as minus forty-four degrees Celsius.

On an Electric or Hybrid there is a third option: freeze protection heats the water automatically whenever the system detects cold, for as long as there is power, so an unattended property does not need draining every time you leave. Plan for a long outage separately, and on a Hybrid the firebox covers exactly that gap.

Siting and setting up

Choosing a location

Most wood fired hot tubs sit on any level surface: ground, deck, patio or concrete pad. What matters is the filled weight.

Size	Diameter	Water	Empty	Filled	Seats
Small	60" (5 ft)	315 gal	200 lbs	3,200 lbs	2 to 3
Standard	72" (6 ft)	420 gal	220 lbs	5,000 lbs	4 to 5
Large	84" (7 ft)	650 gal	300 lbs	7,000 lbs	6 to 8

Seating is for Wood Fired and Hybrid. An Electric seats more per size, 3 to 4, 5 to 7 and 9 to 10, because there is no firebox inside. Depths of 44 and 48 inches add roughly 1,000 lbs to the filled weight.

If the tub is going on a structure, confirm it carries the filled weight at full capacity. That figure is what decides whether a deck needs work, and finding it late is how a project stalls.

Keep the chimney at least ten feet clear of any overhanging structure. Sparks do fly, particularly in dry season, and it is worth confirming exact requirements with your local fire authority. Leave enough room around the tub to load the firebox without brushing against it when hot, and think about where firewood and lids will live.

Rigid insulation beneath the tub is required on concrete, pressure treated wood and gravel, as a protective barrier against dissimilar metals and to avoid denting the base. Two layers, 1.5 inch and 2 inch, giving about 3.5 inches total, is the recommended base for any setup: it improves heat retention and cuts heat-up time. That sits alongside the 360 degrees of insulation around the tub and the floating layer on the water surface.

All three sizes are 38 inches deep, which is also the dimension to know for rolling through a gate or fitting a trailer.

Draining

Plan this before the tub arrives, particularly if you intend to run without filtration, since the tub will be emptied regularly.

The optional Drain Kit takes a garden hose and stubs out from the side, so water empties wherever suits: a garden bed, or back to the lake or ocean it came from. Alternatives include a submersible pump or a siphon.

Without the Drain Kit, a 1.25 inch snap drain plug seals from the inside. With it, use a 1 inch hose and a mechanical clamp, and leave the external valve open through freezing conditions.

Setting up

Cedar tubs supplied as kits can be difficult to assemble without carpentry experience. An AlumiTub arrives pre-assembled, and on a prepared site setup takes about an hour whichever system you have.

1. Set the tub on the prepared insulated base, with the Drain Kit aligned in its channel
2. Wrap the insulation around the outside and tape the seam
3. Position the cedar boards beneath a ratchet strap, working from the front toward the firebox side
4. Secure with the stainless bands: top 4 inches from the rim, bottom 4 inches from the base, middle at 19 inches. Tighten evenly and do not overtighten, which can damage rivets
5. Fit the chimney into the stove collar, place the lid on the firebox, and hang the thermometer on the cedar fence
6. Fill with water, then light the fire

Extra cedar boards are supplied for seasonal shrinkage. Keep them, because gaps will need filling as the wood moves.

At home, off-grid, and for guests

Residential use

Check municipal bylaws before buying, since some areas restrict wood smoke. Because the firebox is submerged, these are generally not treated as an open flame, and they operate much like a household wood stove. When in doubt, ask your local fire department rather than risk not being able to use it.

Dual fuel

If wood use is restricted, or you simply want the option, the Hybrid carries both systems in the same tub, run either alone or together. The common patterns are heating with wood and holding temperature on electric afterward, running both at once to cut the heat time, and heating entirely with wood while the electric side keeps filtration and freeze protection going. Filtration can also be added to a Wood Fired on a standard 120V outlet to extend water life. More in the complete guide to heating options.

Guest properties and short-term lets

Wood fired tubs are in demand with hosts, and for good reason. Without filtration, the tub is emptied and refilled between bookings. With high turnover, filtration and electric heating make far more sense: the water is hot and clean on arrival without briefing anyone on lighting a fire, and a 50 micron filter holds a single fill for three to four months, with no UV or ozone needed.

No UV or ozone needed. Most spas fit them to reduce sanitizer demand, because jets and internal plumbing give water places to sit. An AlumiTub has neither. Keep the water in range and demand stays low on its own. Does your hot tub need UV or ozone? covers it in full.

We hear from hosts every year whose guests lit the fire before filling the tub. That warps the firebox and takes the tub out of service. Make sure guests know to fill to the line first, keep the manual on hand, and show them how to get the fire going.

Delivery

An AlumiTub travels crated on a pallet, on its side, with the seats, firebox, insulation, accessories and cedar cladding secured inside. It ships to your nearest freight depot by default, where a forklift loads it into your truck or trailer. Curbside delivery is available on Small and Standard tubs.

For depot pickup you will want a trailer at least 4 by 7 feet, or a pickup with a six foot bed and 46 inches of clearance between the wheel wells, plus two 20 ft ratchet straps. A second pair of hands makes unloading straightforward. No crane, no contractor.

On a prepared site, setup takes about an hour. The electrical connection on an Electric or Hybrid is made at the same time by your electrician.

Owners have moved theirs by ATV, boat and kayak. The gallery has the evidence.

It continued its journey on a boat trailer then across 2 km of water and to its final location with no problem. Had it filled and heated before dark.

Annie Sperl

For US customers: under the tariffs in effect today, any tariff costs on your order are covered by AlumiTubs, so the price you are quoted is the price you pay. No US sales tax is charged, and US customers also benefit by approximately 30% in savings with the USD/CAD exchange rate. AlumiTubs covers the majority of shipping throughout the US, with a $750 USD flat rate payable at checkout at the time of deposit. Shipments to Alaska and Hawaii may incur a fuel surcharge. Trade policies between Canada and the US continue to evolve, and if they change before your tub ships we will contact you well in advance to explain the impact and discuss your options. Full detail on the shipping page.

Lead times, and why the wait is a good sign

The better manufacturers have lead times, and that is not an accident. Tubs built to order are not sitting in a warehouse. If a supplier can ship immediately, it is worth asking where the tub was made.

AlumiTubs are handcrafted by skilled builders and pressure-tested before leaving the shop. Place a deposit and you are assigned the next available shipping date, with the balance invoiced 30 days before it ships. Nothing about your build is locked in meanwhile: size, heating system and add-ons stay changeable at no charge until that same 30 day point.

Worth the year long wait. So glad I waited. I know I'll be enjoying my AlumiTub for decades to come.

Momo

What to weigh before buying

An aluminum or stainless structure

AlumiTubs pioneered the aluminum wood fired hot tub in 2001 to solve the problems inherent in all-wood construction, and others have followed since.

A metal structure gives durability, hygiene and winter performance, and it can be left empty without consequence because it does not depend on the wood swelling to seal. Marine-grade aluminum is also light enough to move. Stainless is a good option if weight and portability do not matter to you. A fuller breakdown sits in every hot tub material compared.

Fiberglass and plastic are lower maintenance than all-wood, but less hygienic than metal, heavier, and not recyclable at end of life. They also cannot be customized with drain ports, filtration or alternative heat sources.

An internal, submerged firebox

Submerged fireboxes are more efficient and safer. They heat the water directly, and the submerged portion stays cool to the touch, with a cedar fence preventing contact with the hot upper stove and chimney. Paired with insulation and a lid, that is where the heat retention comes from.

Craftsmanship and materials

Locally sourced materials, built in our own shop, inspected and pressure-tested with water before shipping. We can account for every tub that leaves.

The cedar comes from a neighbor, Robert, who lives down the road in Gibsons, British Columbia. He mills only trees that have already fallen or that pose a fire hazard, pulling them out of the forest with a small tractor and a logging arch, and every board is milled on site. We have sourced wood three times now from a single 110-year-old cedar that came down on his property during a winter windstorm. It is slower and more labor-intensive than buying graded lumber, and it is the reason we can tell you where the wood on your tub grew. More on that in how we source our materials.

Room to change later

Drain placement, ports for filtration, and compatibility with other heat sources all matter more in ten years than they do today. A Wood Fired can be built with the optional compatibility ports that allow heating or filtration to be added later without rebuilding the tub, which is what makes going Hybrid an upgrade rather than a replacement.

Serviceability

Worth asking of any tub you are considering: when something eventually needs replacing, can anyone reach it? On an Electric or Hybrid AlumiTub the whole heating and filtration system sits inside the cedar step against the tub, concealed but reachable, with every part replaceable and nothing to dismantle. A wood fired tub has less to service in the first place. Either way, a structure built to last decades is only worth much if the parts attached to it can be reached.

Seating and depth

The Small seats 2 to 3, the Standard 4 to 5 and the Large 6 to 8. On an Electric, each seats more, because there is no firebox taking up room inside. The Large holds more water, which adds to the initial heat time but not to how well it holds temperature.

Depth matters as much as diameter. Too shallow and the tallest person gets a cold shoulder. Too deep and the seats sit low for children. All AlumiTubs are 38 inches as standard, which suits almost everyone. A 44 inch depth is available on Wood Fired and Hybrid, and 44 or 48 inches on Electric.

A good trick before deciding: lay a garden hose out at 5, 6 and 7 feet, sit inside each with the people you will actually be soaking with, and see how it feels.

Service

It is worth doing your homework on a purchase this size. We do not cut corners, we build to the date we give you, and we answer questions when they come. We are a family who want other families to have what we have. Email any manufacturer before ordering and see how the conversation feels. This is not like buying a pair of shoes, and you want to know the company will still be there in a decade.

We have been at this since 2001 and intend to be here in another twenty years, still building tubs we are happy to put our name to. The structure carries a 25 year structural warranty.

We have happily been using our AlumiTub for nearly 20 years. Thank you for building such a remarkable product. I can't tell you about the countless happy hours we have spent in its warm confines.

Heidi and Bruce Reugg