First Use and Burn-In: What Manuals Describe

Why manuals ask for an empty first heat cycle

New sauna heaters, stones, and wood panels carry more than sawdust. During manufacturing, metal parts are coated with light oils to prevent corrosion, wood is treated with sealants and stains, and adhesives bond panels and trim. When you heat the room for the first time, those compounds vaporize. The result is a smell that ranges from mildly earthy to sharply chemical, and in some cases visible smoke or haze near the heater.

A burn-in is simply a controlled way to release those residues before you sit inside. The manual's instruction to run the heater empty, with ventilation open, is not a formality. It keeps the first exposure to those fumes out of your lungs and lets the room cure at its own pace. Traditional saunas in the Finnish style are typically heated to between 150 and 195 degrees Fahrenheit, per Cleveland Clinic guidance, which is enough to drive off most surface residues from the heater and stones.

The same logic applies to steam generators, though the process looks a little different. If you have a steam shower unit, the maker's instructions often call for flushing the generator and running one empty cycle before the first bath, so that any flux, solder, or machining oil inside the tank and steam line is cleared out. Treat the first few cycles as a factory purge, not a test of how the room feels.

• Manufacturing oils on heater elements and metal surfaces.
• Sealants, stains, and adhesives on wood panels and benches.
• Dust and debris packed into stone baskets or between stones.

What the burn-in process looks like

The exact steps vary by brand, but the arc is consistent. Start with the room empty: no towels, no buckets, no people. Open the door or a window if the room has one, and make sure any vents are open. Set the electric heater to its maximum temperature and let it run for one to two hours. You are not trying to hold a comfortable sauna temperature; you are trying to get the room as hot as the heater can manage so that residues cook off quickly.

After the cycle, turn the heater off, leave the door open, and let the room air out fully. Many owners repeat the process once or twice, especially if the first cycle produces a strong odor. Between cycles, wipe down the benches and interior walls with a damp cloth to remove any film that has settled on the surfaces. Do not use soap or cleaner on the wood; plain water is enough at this stage. For more on pre-cleaning, see cleaning before first use.

A few manufacturers suggest starting with a lower temperature for the first 30 minutes, then ramping to maximum. This gentle approach lets the wood and stones warm slowly, which can reduce the chance of cracking stones or warping thin panels. If your manual gives a specific temperature and duration, follow it. If it does not, the one to two hour maximum-heat cycle with ventilation is a reasonable default for a traditional electric heater.

Burn-in for different heater types

Electric sauna heaters, infrared panels, and steam generators each have their own burn-in quirks. For a traditional electric heater, the burn-in focuses on the heater elements and the stones. The stones, especially new ones, can release dust and small particles when first heated, so a quick rinse of the stones before loading them into the basket is common. After the burn-in, you may notice small cracks appearing in a few stones; that is normal and does not affect the heater.

Infrared saunas run at lower temperatures. Cleveland Clinic notes that infrared rooms typically sit between 110 and 135 degrees Fahrenheit, which is not hot enough to fully cure some adhesives and sealants. Many infrared sauna manuals instead recommend a shorter initial warm-up, often 30 to 45 minutes, with the door open, followed by an airing-out period. Because the panels themselves are the heat source, check the panel surfaces after the first few runs for any bubbling or discoloration and keep the area around them clear.

Steam generators follow a different protocol. Manufacturer guidance for steam systems often emphasizes flushing the water tank before first use, because scale and sediment can build up in the reservoir. Run the generator through one complete cycle with no one in the shower, let the steam flow for the full cycle, then flush the unit again. This clears the line and the outlet head of any debris. If your generator has an auto-drain feature, let it complete a full drain cycle before you rely on it. For a deeper dive into the heater-specific first run, see heater first burn-off.

Handling smells and residue after the first heat

A smoky or oily smell during the first burn-in is normal, especially from electric heaters and new wood. The odor should fade as you run the room. If it persists for more than three or four sessions, look for the source. A common culprit is a plastic or synthetic component near the heater, such as a light fixture, control panel, or wire insulation that is not rated for high heat. Check that all materials in the room are intended for sauna use.

After the burn-in, wipe the benches and wall surfaces with a damp cloth to remove any oily film. Pay attention to the floor around the heater, where residue from the stones and elements may settle. Do not use chemical cleaners, as they can leave their own fumes and can strip the finish on the wood. A vinegar solution, one part vinegar to three parts water, can help cut through residue on the heater casing, but rinse it off well and keep it away from electrical connections.

You can also accelerate the off-gassing by running a couple of shorter empty cycles before your first real session. Start with a 20 minute heat at maximum, air out, then repeat. Some owners find that the smell is strongest on the first day and almost gone by the second or third empty cycle.

Safety checks before your first session

The burn-in is also the right time to verify that the safety equipment in the room is working. Check that the smoke alarm is functional before you start the heater, and if you have a carbon monoxide alarm, confirm it is placed correctly. During the first burn-in, leave the room access open so you can walk in and out as needed, and never let a child or pet into the room while it is running.

If the manual mentions the ETL Listed Mark or a similar certification, you can confirm that the heater and control panel have been tested to recognized safety standards. The ETL mark, issued by Intertek, is one example of a mark that indicates a product has been independently tested by a Nationally Recognized Testing Laboratory. This does not replace the burn-in, but it gives you confidence that the components are designed for the temperatures involved. For more on certification marks, see what is a sauna UL listing.

Once the burn-in cycles are done and the room no longer smells strongly of oil or solvents, you are ready for your first real session. Start with a short session of 10 to 15 minutes, per typical guidance from sauna manufacturers, and keep a bottle of water nearby. If you feel dizzy or uncomfortable, step out and cool down. That first session will still have a slight new room smell, but it should be faint and not irritating.

What to pick for your use

Questions

How long should the first burn-in be?

Most manuals suggest one to two hours at maximum temperature with the room empty and ventilation open. Infrared rooms may need less time because their operating temperature is lower. Check your manual for the exact recommendation.

Can I sit in the sauna during the burn-in?

No. The first heating releases oils, adhesives, and sealants that can produce fumes and smoke. You want to be outside the room while those compounds off-gas. Enter the room only to check on the heater or open a window.

Why does my sauna smell like burning plastic on the first heat?

That smell is often the protective oil on heater elements or the adhesive in new panels burning off. It is normal during the first cycle. If it persists for more than a few sessions, inspect for materials that are not rated for sauna temperatures. See our article on sauna heater smells burning.

Do infrared saunas need a burn-in too?

Yes, but the process is shorter. Infrared rooms run cooler, so the off-gassing is less intense. Many owners run one empty cycle for 30 to 45 minutes and then air the room out for a day. Infrared temperatures typically reach 110 to 135 degrees Fahrenheit, so some adhesives may not fully cure in one cycle.

What should I do after the burn-in before my first real session?

Wipe down the benches and interior surfaces with a damp cloth to remove any residue film. Air the room out fully, ideally for a few hours or overnight. Then run one short empty cycle at your normal session temperature. If the room still smells strong, repeat the empty cycle before you sit inside.

Can I pour water on the stones during the burn-in?

No. The burn-in is meant to dry out and cure the stones and heater elements. Adding water while the stones are new can cause them to crack under thermal shock and can spread residue onto the heater casing. Wait until the burn-in is complete and the room is cool before you test loyly. For more on stones, see how to load heater stones.