The Sauna - An actual question

I was in the sauna the other day and the thermometer read 110C and the hygrometer 30%. I can state that it was indeed hot in there. The water in the wooden pail wasn't boiling though, even this had been sitting in there for several hours. Would this be due to the insulating properties of wood? Is it indeed possible to boil water in a wooden pail? I know you can boil it in a paper bag, until the bag falls apart.

IMHO it is due to an environmental temperature of 110C not being sufficient to make it boil, because the evaporation process is cooling off the remaining water enough to keep it from boiling.

I would guess so, yes. For example, you could submerge an electrical resistance in the water.

Correct. Paper doesn't burn at 100C. Neither does wood.

Luc K

If you survived in the sauna for any length of time unprotected, then one of the following is possible:

The thermometer was reading deg F. The thermometer was reading something other than air temperature, e.g. it was receiving direct radition from the hot coals, or was touching part of the fireplace. The thermometer was broken. You are not human.

As humans start dying in large numbers when the external temperature reaches 120-130F (Or less if they are weak or old or the humidity is high).

Your thermometer is broken. It wasn't THAT hot.

The specific heat of water is much greater than the specific heat of air. I'm not sure how many times greater it is, but it is much greater. This means much hot air must be cooled in transmitting its heat energy to the water to achieve a relatively small increase in water temperature. Because the humidity was less than 100%, evaporation was still possible. Of course, evaporation carries heat away from the water into the air. The water in your pail had hit an equillibrium temperature (probably very close to boiling) where heat loss from evaporation was exactly equal to heat gained from the higher temperature air around the bucket. I'd specualte that the equillibrium would move slightly (allowing the bucket water to increase in temperature) as humidity increased. At very high humidities, you might very well see the bucket of water boiling, but I doubt you'd want to go in the sauna then, as your sweat process would no longer be able to maintain your body temperature at a safe level.

Reminds me of the old cliche' 'It's not the heat. It's the humidity.'

When I read this on google, one of the sponsored links was:

Digital Meat Thermometer

Anyway, if the room thermometer said 110C, it was probably wrong. That's comfortably over the boiling point of water, which is 100C, and you would likely not have been able to live through standing around long enough to wonder about the bucket of water. For example, your eyeballs would be poached.

If it was the thermometer on some part of the sauna equipment, then maybe the room was dramatically cooler. For example, maybe the heating equipment for the sauna was close to the thermometer?

Sure it's possible. Wood won't char till considerably above 100C. The insulating property of the wood might be part of it. Another is, the air in the room has a quite small heat capacity compared to liquid water. So it would take only a very small rate of water evaporation to equal the rate of heat supply through the air. So you might not see actual bubbling, just some vapor comming off the surface.

I'm surprised how many people were skeptical of this in this newsgroup. Sauna temperatures can easily rise to 230 degrees Fahrenheit.

Obpuzzle: *why* don't our eyeballs get poached, as another poster suggested would happen such temperatures?

When I lived in Oz it was regularly 120F and we used to work outside picking grapes (no shade) and we certainly didn't die. Drink lots of water and you will survive.

It's strange how many people simply won't believe the temperature of a sauna. 110C is hotter than I prefer, but not abnormal. Despite what some of the replies have said you can survive it quite happily for a suitably limited period of time.

In answer to the original questions though, the wooden pail was almost certainly sitting on the floor, and the thermometer was up near ceiling level. The sauna should have a fresh air vent near floor level and another vent high up to let hot air out. This ensures a suitable temperature gradient throughout (why else do you think you have a choice of seating heights?).

I would guess that if you try the thermometer at different heights, with 110C near the top you would probably get 80C at upper bench level, and maybe 30-40C at ground level. If the floor of the sauna got hot you would soon notice it when going in or out!

I can't remember where I saw it, but several years ago I read about how people used to sit in ovens while meat cooked right next to them.

The ovens were not the type in use today, the heat was produced by burning wood or charcoal. Lets say that the oven was a 4'' x 4' x 5'H metal box, inside it was a container for the charcoal which sits 3' above the bottom, a grill above it for the meat, at the top is a flue for the smoke to escape.

At the bottom, on the back where it can't be seen by spectators is a vent for incoming air. The person inside the oven sits on the floor next to the vent, the heat from the coals will all rise up the flue, while the person is kept cool by the incoming air. It may have been a bit hot, but not nearly as much as it appeared.

Just as in the sauna mentioned in this thread, it is very hot at the top, and much less so near the bottom. Add a little showmanship, and you have 'the fireproof man'.

This is false. Sauna air temperatures range from 150F-200F. Personally, I find 180F to be about right. 110C (230F) as the poster says is extremely hot, but it certainly won't kill you to be in there for a moment or two.