How Much Does It Cost to Run a Wood Fired Hot Tub

A wood fired hot tub has no electricity running costs. The ongoing expenses are firewood and water per use, plus modest annual water care. For most owners soaking two or three times a week, the total sits well below a comparable electric spa, with firewood cost varying considerably depending on how it is sourced.

What you do and do not pay for

Part of what makes a wood fired hot tub appealing is how simple it is. It can be used like a campfire, session by session, or more like a wood stove. Depending on your property, it can be inexpensive or close to free to run.

The cost picture is fundamentally different from a conventional spa. There is no heating element drawing power, no pump running continuously, and no control system consuming standby energy. The energy bill is zero.

What you pay per use: firewood and water. What you pay annually: water care, if you maintain the water rather than draining after each visit.

The trade-off is that cost per use is variable and tied to how you source wood, where an electric tub has a predictable monthly figure. For most owners, particularly anyone with access to wood at low cost, the wood fired model works out considerably cheaper.

Firewood, the main running cost

How much does a single soak use?

Heating a Standard 6ft AlumiTub from cold uses roughly one to two bundles of hardwood, or the equivalent in cord wood, over around three hours. The Small takes about two hours and the Large about five, so wood use scales with size. The exact amount depends on:

• Starting water temperature
• Outdoor temperature and wind
• Whether the lid stays on during heating
• The density and dryness of the wood

It heats quickly and is very efficient using much less firewood than I had ever thought.

Dave Bishop, Yosemite

Drier, denser hardwood produces more heat per piece. Wet or soft wood burns less cleanly and needs more volume for the same result, so wood quality affects both cost and heat-up time. The art of heating a wood fired hot tub covers running the fire efficiently.

The second soak costs far less than the first

Worth knowing before you budget by the session. Three layers of insulation, 3.5 inches of rigid board beneath the base, 360 degrees around the tub and a floating layer on the water surface, mean a heated tub loses only two to three degrees Fahrenheit overnight with the lid on. Soaking two evenings in a row is one full heat-up and one small maintenance burn, not two full heat-ups.

Cost by source

Source	Relative cost per session	Notes
Locally sourced or foraged	Minimal to zero	Most common at rural and recreational properties
Bulk cord wood	Lowest of the purchased options	Depends heavily on region and species
Kiln dried bags	Mid range	Convenient, burns cleanly, widely available
Retail bundles	Highest per session	Least economical, fine for occasional use

Firewood prices vary enormously by region, season and species, so the useful comparison is between sources rather than to a fixed figure. Owners in forested areas, or anyone managing their own timber, often have wood at negligible cost. For urban owners buying kiln-dried bags, the cost is higher but still typically lower per session than running an equivalent electric spa.

Dense hardwoods such as oak, ash, maple and birch give the most efficient burn. Softwoods ignite easily but burn faster. More in the guide to the best firewood to use.

Water costs

A Standard tub holds 420 gallons, the Small 315 and the Large 650. At municipal rates that is a minor cost per fill, though worth factoring in if you drain and refill after each period of use, which is the standard approach without filtration.

Many owners fill from a well, lake, river or the ocean, which removes the cost entirely. More on that in water access at a remote property, and on how long a fill lasts in how often to change hot tub water.

Others add filtration, which extends the time between fills considerably: three to four months rather than a week or two. The filtration add-on for the Wood Fired runs on a standard 120V outlet, plug and play, and keeps water clean between soaks.

A Wood Fired AlumiTub can also be emptied and left standing empty until its next use, which an all-wood cedar tub cannot.

Water care costs

Used in the simplest way, filling and draining around each visit, water care costs are essentially nothing. Fresh water, no treatment, drain.

For anyone holding water longer, some treatment is needed. Good Clean Living Water Care is built for sanitizer-light ownership: a hose filter to start clean, balancing to keep the water in range, and a monthly plant-derived stabilizer for tubs left filled. On systems with filtration, a filter cleanser and booster keep it running.

Annual product cost for a Wood Fired owner is modest. The six month kit is designed for year-round use on an Electric system, and on a Wood Fired used seasonally it stretches considerably further.

Holding the water in range is what keeps that figure low: alkalinity 80 to 120 ppm, pH 7.4 to 7.8, calcium hardness 150 to 250 ppm and bromine 2 to 3 ppm, never above 3. Correcting water that has drifted always costs more product than keeping it in range would have. Water chemistry for an aluminum hot tub sets out the routine.

Maintenance costs almost nothing

This is the shortest section on the page, and that is the point. Beyond firewood, water and water care, there is very little an AlumiTub asks you to spend money on.

• Clearing the firebox costs nothing. The ash scoop comes with the tub
• Checking the chimney cap at the start of each season costs nothing either. The cap comes with the tub
• Cedar care is optional. Cedar silvers as it weathers, and plenty of owners leave it to. If you would rather keep the original tone, an occasional oil or sealant does it, but nothing is required
• Filters are replaced every three to four months on Electric and Hybrid tubs, and on a Wood Fired with the filtration add-on fitted. A Wood Fired without filtration has none
• A lid is a one-time purchase rather than a running cost, and it pays for itself in wood

The 25 year structural warranty covers the tub body, so there is no repair fund to plan for either. The aluminum does not degrade, and the cedar ages rather than deteriorating.

There is also no service call in the picture. A wood fired tub has very little to go wrong, and on the Electric and Hybrid the entire heating and filtration system sits inside the cedar step against the tub, concealed but reachable, with every part replaceable. That is a different long-term cost profile from a conventional spa, where components are sealed inside a cabinet and reaching a failed one means a technician.

It's literally the lowest maintenance thing at our cabin. Durable, well-built, fast heating.

The Rural Runaway

How hard a wood fired hot tub is to maintain covers the time cost rather than the money cost, which is the one most owners actually care about.

Wood fired against electric

Putting a dollar figure on what an electric spa costs to run is not something anyone can do honestly, and any article that gives you one is guessing. The number moves with local electricity rates, which vary several-fold across North America, with climate, with how well the tub is insulated, with whether heating and filtration can be scheduled, and with how disciplined you are about the cover.

What can be said is the shape of it. A conventional spa holds temperature around the clock, so it draws power whether or not anyone soaks that week. The bill arrives regardless.

The AlumiTub Electric is designed against that pattern rather than fitting it, and the design choices are exactly the variables above. The same three layers of insulation keep the heat where you put it, so the heater cycles gently to hold your setting rather than working constantly to stand still. A single 30 gpm jet at the lowest workable horsepower replaces a bank of jet pumps. And heating and filtration both run on timer schedules, so the system sits idle through the days when nobody is soaking. The cedar tub that stays hot covers how that works in practice.

A wood fired tub is the other extreme. It consumes nothing at all when unused, and the spend is entirely optional: you pay for the sessions you actually have, in wood you may well already own.

For occasional and weekend use, the wood fired advantage is clearest. For daily use the gap narrows, though wood fired still avoids the grid cost and the electrical installation. A Hybrid is the option that gets at both: heating from cold is where almost all the electricity goes, so letting the fire do that and the electric side hold temperature afterward removes the largest single draw while keeping filtration running.

Worth remembering that installation is a cost too. An AlumiTub arrives pre-assembled and rolls into place at 200 to 300 lbs, so there is no crane hire on delivery day, and the wood fired model needs no electrician either. Wood fired against electric spas compares the two in full.

We were surprised that the price was actually less than other wood fired hot tubs that don't have the aluminum interior.

The Rural Runaway

How to reduce running costs

• Source wood locally. Even buying a cord in bulk beats retail bags considerably
• Season your own. Wood cut and dried for twelve to eighteen months burns far more efficiently than green timber
• Use the lid while heating, and between soaks. Heat loss through the water surface is the largest single loss, and the lid is what turns the next day's heat-up into a small maintenance burn
• Fill with warm water where you can. Starting higher shortens heat-up and reduces wood consumed
• Stop adding wood at around 95°F. The water climbs the rest of the way to a 101 to 104°F soak on its own, so wood added after that point is largely wasted
• Add filtration if you soak often. Extending water life cuts both water and treatment costs