Sauna with Radiators......Help

Alan(CaliforniaRadiant)Forbes

We just bid on a job a few weeks ago; it's a health clinic. There's some floor warming and some floor heating; about 2,000 [] total.

The contractor calls back and says that he wants to heat one of the rooms to 120° and use it as a sauna. I told him to get a separate unit, like a Mr. Sauna, but it's like he doesn't hear me; he wants me to do it with our boiler.

So I get to thinking about it; I could do a heat calc. on the room and plug in 120° for an indoor temperature (I don't know if the Slant Fin program will go that high, but maybe Siggy's Hydronic Toolbox will), but I know that conventional thermostats won't go that high. I suppose I could use something like a Honeywell aquastat. We would have to use a large radiator to get that kind of temperature; I don't think radiant would get it hot enough, fast enough.

Any ideas?

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Unknown

Steam

Saunas and kilns (like in lumber kiln) can work with steam. You really need to move some BTUs to keep any size space that hot.

But you can do it. I've worked on a kiln that you drove a truck through, in NH.

Noel

Mike T., Swampeast MO

Weird idea again...

How much can you control the construction of the space?

If answer is "completely" AND the space is to be MAINTAINED at a high temperature...

Double walls and ceiling with a 3" or so thick layer of extruded polystyrene continuous between the two wall units AND the wall cavities filled with extruded polystyrene as well. 6" or so between the ceiling layers.

Warmboard or continuous Thermofin ("D" type) walls, floor and ceiling--preferably with COPPER tube. Baltic Spruce or other appropriate wood* applied over the warmboard. If there are benches (I would presume there will be) DO NOT use the warmboard or thermofin directly in the "head zone" of occupants!!!!

DEDICATED manifold serving this room with individual loops about 10 times shorter than you would otherwise use--all in reverse return of course

Perhaps Danfoss makes a suitable proportional device (maybe not used the way it's intended to be used) that can operate at such a temperature...

Using this construction I believe you would still have a condensing boiler condensing--well...

Possible problem: the radiation may OVERWHELM the occupants as the walls will STILL have to be somewhat warmer than the air. This is the OPPOSITE of a REAL sauna. Remember that "sauna" is Finnish and they work with lowly ("thrown water" to create steam) to produce INCREDIBLE dewpoints. The SURFACES though won't be as hot as the air! The Fins don't comprehend the "American" idea of a "dry" sauna. Thus the reason I mentioned keeping the conduction sources out of the "head zone".

*I'm guessing they want wood. Even drywall could be used (I guess) but NOT if large amounts of humidity are being added. Don't forget that it takes LOTS of water vapor to make 120 degree air have a "normal" humidity level.

In case you're interested a modern "true" Finnish sauna heater amounts to a big lidded, well-insulated can full of rocks kept constantly HOT. You lie down or hunch with your head close to the ceiling--that's why real saunas have HIGH benches--and add water and let the rocks make steam. The air only gets hot because there is so much steam...

Paul Cooke

Alan

If your client wants an authentic sauna experience I suggest you steer him to a system that incorporates a heater that has hot rocks as the heat source. That's what is needed to create the right type of heat. Temperature is only a small part of the traditional sauna.

Here's a good link with sauna info:

http://www.cyberbohemia.com/Pages/sweat.htm

Paul Cooke

Another good site

http://www.saunasite.com/index-en/building.htm

Quote from the website:

The heat is stored in a large amount of stones
The temperature in the sauna is quite mild, 60-80 C
The feel of warmth is regulated by throwing water onto the hot stones

Don't know if you can do that with a radiator.