Heating

views updated Jun 11 2018

HEATING

HEATING. House warming continued to depend on the primitive fireplace, often without a chimney, through the seventeenth century. In the mid-eighteenth century, the first steps were taken in developing a science of heat as the thermometer came into use and the effect of absorption and release of heat on evaporation and freezing (latent heat) was observed. By the end of the century, scientists were measuring the heat generated by combustion and other chemical and physical processes. Stoves were being designed on these new scientific principles, especially in France.

In 1744 Benjamin Franklin issued a pamphlet describing his famous "Pennsylvania fireplace." Stoves were already in use in America, especially by German immigrants, but they were not "scientific"—Franklin's stove was, thanks principally to information previously published in Europe. Invented in 1739 or 1740, Franklin's fireplace, while set into the existing house fireplace, projected into the room to achieve the maximum possible heat radiation. The smoke followed a circuitous route in reaching the chimney so as to extract the maximum possible heat from it.

In Europe ancient architectural traditions inhibited the introduction of stoves, which were usually as unaesthetic as they were utilitarian. In America, Franklin's fire-place was not particularly popular either, but it ushered in a fever of invention of what came to be called Franklin stoves, Rittenhouse stoves, or Rumford stoves—the second

being a more efficient version of the first, and the third, a by-product of the multifarious activities of Benjamin Thompson, an American Tory living in Europe (where he was known as Count Rumford). Rumford's activities ranged from the study of the science of heat to the organization of public soup kitchens that incorporated elaborate cooking stoves. Most complicated of the new stoves, perhaps, were those designed by Charles Willson Peale and his son Raphael to heat Independence Hall, where Peale had his museum. Through the above inventions the stove gradually became independent of the fire-place, which it replaced as the household hearth. Stove plates—that is, the sides and backs of stoves—became the largest single product of the American iron industry.

Central heating, the warming of entire buildings, had been known in ancient times to both the Romans and the Chinese, both of whom made hollow heating ducts in the floors and walls of houses. The American architect B. H. Latrobe made such an installation in the U.S. Capitol building in 1806. But more common was the kind of central heating introduced by Daniel Pettibone in 1808 in the Pennsylvania Hospital in Philadelphia. It was a stove in which the smokepipe was enclosed within a larger pipe through which hot air circulated to five upper-story rooms. In either case the principle of convection was used: hot air expands on heating, causing it to be lighter and to rise, thus inducing a vacuum that cold air rushes in to fill (and to be heated). A general circulation and mixing of the air results.

Heating by passing hot water through pipes had been used in European horticultural greenhouses in the eighteenth century, and this method was subsequently used to heat buildings as they became too large to be heated efficiently by stoves. The U.S. Capitol, which seems to have seen experimentation with all types of heating, was adapted in 1857–1867 to hot-water heat. At the same time, many factories came to be heated by the "waste" heat from the steam engines with which they were powered, and piped steam became an alternative to hot water. Both systems were installed in the skyscrapers—far too large to be heated by stoves or by the natural convection of hot air—that began to appear in Chicago in the 1880s.

The heating properties of natural gas were known as early as the nineteenth century, but transporting the gas proved a technical barrier until after World War II when advances in metallurgy and welding allowed the construction of thousands of miles of pipe by the close of the 1960s.

The 1973 oil crisis caused many families to investigate alternative heating strategies for their homes. Some turned to natural gas and new solar technology, while most individuals began investigating how to seal door and window leaks that increased heating bills. The trend formed the foundation of the first U.S. Department of Energy weatherizing assistance program, which continued to operate through the close of the twentieth century.