Quotes on Fire and Hearth

For 1.5 million years, we enjoyed the radiant heat of the ancient wood fire. We used rocks to secure the fire and as kitchen utilities. The cave people found heat from their fires stored in and slowly radiating from the cave walls. As our building knowledge grew, man figured out how to tame the fire and how to store its heat more and more effectively.

We abandoned caves in favor of houses with stone fireplaces. As winters set in, the fireplace became the center of every home, where we could eat and sleep after a hard day of hunting and gathering. Even today we crave the safety of hearth and home.

About 50 years ago, we started to heat our homes and businesses more and more with forced hot air, the kind used with radiators and central air. Fireplaces were phased out, especially in the cities. Radiant heat became a cozy memory.

Forced-air heating uses the same principles used in a hot air balloon. We heat metal plates with hot water or electricity. These plates heat the air around them and this heated air is forced through the room so that air is heated and rising all the time. While this hot air might manage to keep us warm, it does little else.

To understand the implications of the transition from radiant heat to forced-air heat, we have to understand the effects of various kinds of heat on our bodies.

Man has dwelt in rather hot areas for most of our evolution. So our inner thermostat is focused on cooling down in order to keep our body temperature stable at around 96 degrees Fahrenheit.

When we digest the food we eat, we produce heat. so our body has to assure that this heat can be expelled. Most of this heat transfer happens through the skin, which has an average temperature of 86 degrees. If you’re too hot, the body pumps more warm blood to your skin, which turns red.

When this happens you actually radiate about the same amount of heat as a 100 Watt light bulb. The body also uses the cooler surrounding air, evaporation and breathing as other ways of cooling down. When traveling into colder areas, man found that there was little his body could do to help him keep warm. Cold causes blood to move away from hands and feet in order to reduce heat losses, which is why cold turns you blue. If the body remains cold it begins shivering, and teeth begin chattering. These muscle movements create heat. That’s why prehistoric man developed warm clothing and warmer shelter, and used fire to keep warm.

Basking in the sun and sitting by your Tulikivi fireplace both help to keep your body warm in the same way. Scientists call it radiant heat. it’s a kind of light that you can’t see. It has nothing to do with radioactivity! Cats see it quite clearly and use it to catch mice in the dark.

Heat rays are also called infrared light, because their wavelength is somewhat longer than red light. Infrared light will heat up every object it falls upon. Heat rays from very hot objects can penetrate up to four centimeters deep into your body, though around one millimeter is quite enough. This is where about a quarter of your blood flows to distribute heat throughout your entire body. As long as the temperature of the heat source is higher than that of your skin, you experience a direct heat transfer. that’s why sitting near a Tulikivi feels so great when you are coming in from the cold.

With radiant heat, room air can be relatively cold (64- 68 degrees) because the deep-heating rays compensate. But the average heated room air doesn’t heat up your body in the same way. Your skin loses heat to warm air, albeit less than with cold air. Forced-air heating only helps create an environment, which is warm enough to keep your body warm through your own inner fire. If room air gets too warm, it may cause you to breath more quickly to remove heat, which may result in a restless, constricted feeling.

Conversely, cold radiation is rather unpleasant. Cold stored in walls and floors can keep you feeling colder. This syndrome is typical with forced-air heating systems, which heat up room walls only marginally. Even if the room air is rather warm, the cold radiation will cause the blood to withdraw from the skin.

The soapstone heat from our fireplaces vibrates at precisely the same wavelength of your body radiation, at 8-9 µm. Scientists say this explains a lot about the general appreciation for the quality of our heat, which we have recorded over the years. The wavelength of hot metal surfaces is much shorter. It feels aggressively hot when close by, but does not reach far.

Forced-air heating produces a vertical temperature difference of up to 50 degrees, producing a warm head and cold feet. Your body can’t adjust to that. The thermostat in an air heating system controls the air temperature at the level of the thermostat, while creating the illusion that a desired "room temperature" has been achieved. But to be really comfortable, the room would need to have height differences, as in a sauna.

With radiant heat, the heat difference is horizontal. So, by moving closer to or further from the heat source, both older people sensitive to cold and younger people can find an area in the same room where they feel comfortable.

Some years ago, as I looked into the various traditional methods of wood burning around the world, the depth of feeling among masonry stove partisans began to come home to me. They did not simply feel that masonry stoves were better; they felt that, given an opportunity for choice, no other choice could be made! At this point, rather like the mule struck by the baseball bat to get his attention, I began to feel that there might be a message here for North America. The farther I looked, the more relevant the message seemed. Masonry stoves were superior in a number of ways...

We are accustomed to iron stoves. That is our tradition. Elsewhere in the world, many prefer masonry. So let me begin by listing some of the virtues that well-designed masonry stoves and fireplace-stoves may have:

	They are substantially more efficient than the typical iron stoves on the market today.
	They are safer to live with than iron stoves.
	They can sharply reduce air Pollution from smoke.
	They fit in well with solar heating....
	Masonry Stoves require fuel only once or twice a day.
	They do not parch the room air and so are more comfortable to live with than iron models.
	They offer design flexibility impossible with iron; the masonry stove can be designed to fit the house.

"As to the present value of old technology in stoves, look for a moment at Finland. Finland is an advanced country, known for fine workmanship and good design. The Finns are international traders. Their products have to be good, especially in regard to heating because their climate is like that of Alaska. Today (1984) Finland’s government actively encourages the construction of masonry stoves through tax policy. About two-thirds of Finland’s new houses have built-in masonry stoves. Most of the rest have wood-fired masonry baking ovens which can also be used for space heating. This government policy says a good deal about Finland’s confidence in an old technology, even in the space age. It says something as well about the country’s assessment of the energy situation.

Masonry stoves can sharply reduce wood-burning safety problems. The iron stove is frequently so hot that it will burn anyone who touches it. The masonry stove is commonly designed in Europe with benches attached, so that you can sit and lean against the stove. There is a world of difference in safety between a stove you can lean on and one that burns at the touch.

Reprinted from The Book of Masonry Stoves — Rediscovering an Old Way of Warming

Initially Published by Brick House Publishing 1984
Now published by Chelsea Green Press – White River Jct., Vermont

This pattern is a biologically precise formulation of the intuition that sunlight and a hot blazing fire are the best kinds of heat.

Heat can be transmitted by radiation (heat waves across empty space), convection (flow in air or liquids by mixing of molecules and hot air rising), and conduction ( flow through a solid).

In most places, we get heat in all three ways from our environment: conducted heat from the solids we touch, convected heat in the air around us, and radiated heat from those sources of radiation in our line of sight.

Of the three, conducted heat is trivial, since any surface hot enough to conduct heat to us directly is too hot for comfort. As far as the other two are concerned - convected heat and radiant heat - we may ask whether there is any biological difference in their effects on human beings. In fact there is.

It turns out that people are most comfortable when they receive radiant heat at a slightly higher temperature than the air around them. The two most primitive examples of this situation are: (1) Outdoors, on a spring day when the air is not too hot but the sun is shining. (2) Around an open fire, on a cool evening.

Most people will recognize intuitively that these are two unusually comfortable situations. And in view of the fact that we evolved as organisms in the open air, with plenty of sun, it is not surprising that this condition happens to be so comfortable for us. It is built into our systems, biologically.

Unfortunately, it happens that many of the most widely used heating systems ignore this basic fact.

Hot air systems, and buried pipes, and the so-called hot water "radiators" do transmit some of their heat to us by means of radiation, but most of the heat we get from them comes from convection. The air gets heated and warms us as it swirls around us. But, as it does so it creates that very uncomfortable stuffy, over-heated, dry sensation. When convection heaters are warm enough to heat us we feel stifled. If we turn the heat down, it gets too cold.

The conditions in which people feel most confortable require a sublte balance of convected heat and radiant heat. Experiments have established that the most comfortable balance between the two, occurs when the average radiant temperature is about two degrees higher than the ambient temperature. To get the average radiant temperature in a room , we measure the temperature of all the visible surfaces in a room, multiply the area of each surface by its temperature, add these up, and divide by the total area. For comfort, this average radiant temperature needs to be about two degrees higher than the air temperature.

Since some of the surfaces in a room (windows and outside walls), will usually be cooler that the indoor air temperature, this means that at least some surfaces must be considerably warmer to get the average up.

An open fire, which has a small area of very high temperature, creates this condition in a cool room. The beautiful Austrian and Swedish tiled stoves also do it very well. These are massive stoves, made of clay bricks or tiles, with a tiny furnace in the middle. A handful of twigs in the furnace give all their heat to the clay of the stove itself and this clay, like the earth, keeps this heat and radiates is slowly over a period of many hours. ...

Choose a way of heating your space - especially those rooms where people are going to gather when it is cold - that is essentially a radiative process, where the heat comes more from radiation than convection. ...

...it is also very wonderful to make at least some part of the radiant surfaces low enough so that seats can be built round them and against them; on a cold day there is nothing better than a seat against a warm stove.

From A Pattern Language by Christopher Alexander, Sara Ishikawa, Murray Silverstein

"The slowness of one section of the world about adopting the valuable ideas of another section of it is a curious thing and unaccountable. This form of stupidity is confined to no community, to no nation; it is universal. The fact is the human race is not only slow about borrowing valuable ideas — it sometimes persists in not borrowing them at all.

Take the German stove, for instance — to the uninstructed stranger it promises nothing; but he will soon find that it is a masterly performer. The process of firing is quick and simple. At half past seven on a cold morning one brings a small basketful of slender pine sticks and puts half of these in, lights them with a match, and closes the door. They burn out in ten or twelve minutes. He then puts in the rest and locks the door, and carries off the key. The work is done. He will not come again until next morning. All day long and until past midnight all parts of the room will be delightfully warm and comfortable.

Americans could adopt this stove; but no, we stick placidly to our own fearful and wonderful inventions of which there is not a rational one in the lot. The American wood stove, of whatsoever breed, is a terror.

There can be no tranquility of mind where it is. It requires more attention than a baby. It has to be fed every little while, it has to be watched all the time; and for all reward you are roasted half your time and frozen the other half. It warms no part of the room but its own part; it breeds headaches and suffocation, and makes one’s skin feel dry and feverish; and when your wood bill comes in you think you have been supporting a volcano.

Consider these aspects of the Masonry stove. One firing is enough for the day; the cost is next to nothing; the heat produced is the same all day, instead of too hot and too cold by turns; one may absorb himself in his business in peace. Its surface is not hot; you can put your hand on it anywhere and not get burnt, yet one is as comfortable in one part of the room as another"

We agree. Residential Masonry Heating is as valid today as it was during Mark Twain’s time. Built to last, Masonry stoves manage to combine beauty with proven energy efficiency.