Frequently asked questions

Work from room volume, not a person count. Measure the finished internal dimensions after lining, multiply length by width by height for cubic feet, and pick a heater whose manufacturer-published range contains that number — Harvia rates its 6 kW models for 177 to 283 cubic feet. Add capacity for an uninsulated room, a large glass panel or a cold climate.

Every electric heater above roughly 4.5 kW does, and most residential heaters are 6 kW or 8 kW. Infrared cabins generally do not — a 2,100 to 2,240 W cabin runs on a dedicated 20 A, 120 V circuit. A wood-fired stove needs no electricity at all, which is why it is worth pricing when a long garden run is expensive.

At the upper bound, a 6 kW traditional heater for a 45-minute session uses 4.5 kWh — about $0.77 at $0.17 per kWh. A 2,240 W infrared cabin uses 1.68 kWh, about $0.29. Both assume rated draw throughout, which overstates the real figure because elements cycle once the room is hot.

Around 30 to 45 minutes from cold for either infrared or traditional, and longer in an unheated garage or an outdoor barrel in winter. No manufacturer publishes a figure. It is why scheduled preheat is worth more than its price suggests — it is what turns a spontaneous session into a plan.

A traditional sauna heats the room to 175 to 195 °F with a stove full of stones, so the air itself is hot and you can throw water for steam. An infrared cabin uses panels that warm your body directly while the air stays at 120 to 150 °F. Both make you sweat; only one feels like a hot room.

Not for an unqualified claim. Of the products we surveyed, one in eight published a numeric EMF figure and none published the distance it was measured at — and field strength falls off sharply with distance, so a figure without one cannot be compared to anything. Spend the premium on specs that are actually published.

Cedar outdoors, where its rot resistance is decisive for a structure facing rain and freeze-thaw. Hemlock indoors, where cedar is solving a problem that does not exist and hemlock's lack of aroma suits anyone who finds cedar strong in an enclosed cabin.

Manufacturers generally advise inspecting them at least annually and replacing those that crack or crumble. It matters more than it sounds: degraded stones restrict airflow through the heater, which makes the elements run hotter and is the most common cause of premature element failure.

Roughly: 1/3 HP for up to 100 gallons in an insulated tub indoors, 1/2 HP for 100 to 150 gallons, and 1 HP for anything larger or anything outdoors in a hot climate. No manufacturer publishes a volume rating, so that is reasoning from published cooling capacities and heat-load math rather than a quoted spec.

Published cold water immersion research commonly works between roughly 50 and 59 °F. Every mainstream chiller reaches at least 42 °F, so minimum temperature is rarely the constraint — capacity against your tub volume is. Colder is not automatically better.

It depends on inputs only you have: local ice price, tub volume, session frequency and electricity rate. Four or more sessions a week in a tub over 100 gallons, a chiller pays back reasonably quickly. Two or three times a week in a small insulated barrel, ice stays defensible for a long time.

In order of likelihood: no lid, direct sun, poor insulation, and only then an undersized chiller. The open water surface is the biggest heat path in any cold plunge, so a fitted insulated lid is the first fix and usually the only one needed.

If the water sits for more than a day or two, both — they do different jobs. A filter removes visible debris; ozone deals with biology. Filtering alone gives you water that looks clean and is not. If you run ozone, add a venturi injector, or most of it escapes to the air rather than dissolving.

There is research suggesting cold immersion immediately after resistance training may blunt some hypertrophy and strength adaptations. It is a timing question rather than a reason to avoid cold — if adaptation is your goal, put the cold at a different time of day or on a rest day.

It is the right question and it is close to unanswerable from listings. Across every panel we surveyed, at every price point, none published irradiance at a stated distance — and dose is irradiance times time. We compare on wavelength, LED type and board area instead, and say plainly that this is a compromise.

They do different things. 660 nm red is absorbed close to the surface, where most skin research sits; 850 nm near infrared penetrates further, where most deeper-tissue work sits. A dual-chip panel emits both from every diode, which is why dual chip is a meaningful spec rather than a marketing term.

Not for convenience, possibly for control. A cabin tube sits at whatever distance the cabin puts it; a panel can be positioned inches away, and distance determines dose. Note that most panels are not specified for sauna temperatures, so using one outside the cabin avoids that question.

No, and every page says so. We compile published manufacturer specifications, compute running costs and sizing from first principles with the working shown, and cite sources with dates. We hold no test equipment and own none of the products covered.

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Because we only build a direct product link when we confirmed that exact listing against a live page during the build. Where that check failed — Amazon serves bot-check pages to automated requests much of the time — we link a tagged search instead, which always resolves to live stock rather than risking a dead page.

There are no customer reviews, testimonials or star ratings anywhere on this site, and there never will be. Everything here is editorial assessment of published specifications, written by one named author. We would rather have no testimonials than invented ones.

Through the contact page, and it goes to the front of the queue. If we have misread a spec, cited a source that does not support the claim, or linked something that has died, we fix it, date the change and describe it.