XVIII.

FORCED BLAST WARMING WITH FURNACES.

BY GEO. W. KRAMER, NEW YORK.

(Non-member of the Society. Presented to the Society on request.)

No new principle is involved in the use of a furnace to warm the air of a building. Neither is there anything novel in the movement or distribution of air through ducts by means of a fan, yet natural as the combination of the two may seem, there are comparatively few instances where this has been successfully accompished.

My experience in connection with the installation of several systems of this character will probably explain why I have been requested to submit a paper on this subject, wherein I should state the reasons for, the results of, and the conclusions deduced from, placing apparatus in the combination heretofore referred to.

A brief prefatory explanation is essential prior to making this statement. In my practice as an architect I have planned buildings located in over one-half of the states of the Union, thus becoming familiar with and meeting the various climatic as well as other local conditions, such as exposure, protection, materials, construction and character as well as the prejudices and preferences peculiar to the clientele.

All systems of heating, by steam, hot water and hot air have been utilized, in combination with the various methods of securing ventilation. In this I have had no prejudices, preferences, fads, or hobbies, but freely used what I deemed best adapted to each individual case.

As a specialist in ecclesiastical work I have had in recent years more to do with churches than any other class of buildings. The peculiar conditions, which are probably more complex than pertain to any other class, should first be considered.

The modern church consists generally of two auditoriums, one, the church proper, the other, the Sunday-school. These auditoriums are quite frequently arranged so as to be combined or thrown together. The Sunday-school consists of a number of subordinate apartments, also arranged for separation or combination. In

addition there are generally various other apartments of a subordinate character. Nine-tenths of the churches are used as a whole but one day of the week. The periods of use vary from two to three hours at a session, generally a short session in one portion then in the other, frequently using the two auditoriums in combination, and occasionally using the entire building. This generally occurs during the most severe weather. Ventilation is most essential when the most adverse conditions prevail. Thus, there are ever varying conditions to this most complex problem and each application must be solved in accord with the governing conditions.

The apparatus must be efficient and sufficient, noiseless, combine safety and simplicity with economy, both of first cost and maintenance, automatic in operation (or as nearly so as possible), as brains cannot be incorporated and are seldom employed to operate or care for the building or apparatus. A uniform temperature and plenty of fresh air must be secured and the building must be quickly heated and controlled under always varying conditions.

For the larger and better class of churches, where continuous fires are maintained, and skilled employes in charge, no better system can be devised than indirect steam or hot water in connection with mechanical propulsion of air, all properly and scientifically installed.

Direct steam or hot water should not be used, except for halls, corridors, lobbies, etc., as no perfect system of ventilation can be combined with direct radiation. With many, a prejudice exists against placing a boiler with the necessary, pipes, valves, pumps, traps, feeders, and consequent paraphernalia in the church, all of which bewilder the average mind as being very complicated; that damages arising from carelessness, leaks, freezing, etc., in connection with the necessary repairs frequently cost more than the maintenance, to say nothing of an occasional explosion.

Thus for the majority of churches this would leave the so-called hot air furnace as the only recourse. The limited distance to which heated air can be conveyed by gravity necessitates in the complicated modern church a distribution of apparatus, fuel, and pipes that practically render the basement useless for other purposes. Satisfactory, continuous and controllable ventilation is difficult if not impossible.

The necessity for utilizing the various possible apartments of the basement, suggests the concentration of apparatus. A central location for the apparatus is essential to equalize the distribution.

The large distributing ducts, placed necessarily at an elevation, prove as objectionable as the distribution of apparatus, atmospheric conditions often rendering them inoperative, when their services are most required.

The application of the fan suggests itself, with a concentration of apparatus in a portion of the building least required for other purposes, using smaller and concealed conduits. On investigation I ascertained that this combination was considered impracticable, but could find no existing example as evidence that this condemnation was other than opinion based on untried theories or prejudices without foundation. Previous experience was not of such a character as to lead me to place implicit confidence in theories, many of which operate most successfully when reversed; consequently I determined to make a test for my own satisfaction.

An opportunity soon offered. Having at that time a church of about 250,000 cubic feet capacity, in which I was free to introduce

NEW HIGH STREET CHURCH OF CHRIST, AKRON, O. WEARY & KRAMER, AR'TS.

any system I desired, results being the only condition, I concluded to make the experiment, having no doubt of success in some degree.

Having no precedent to guide, all supply, distribution, and installation was calculated on the same basis on which we install a blast system using steam, substituting warm air furnaces for the steam heating coils, however. For the purpose of equalizing pressure, distribution, and temperature, I arranged for much larger reservoirs.

I desired to secure a furnace which I thought competent to do

the work, and in which a proper amount of grate surface was combined with a great amount of so-called radiating surface. Calculating from a steam basis I could ascertain the grate surface necessary to produce the heat, reasoning that the same amount of fire should do the same work.

I knew from experience that from one-third to one-fourth the radiating surface in connection with the fan, as compared with direct radiation in steam practice, would produce the same results. Would the same relative condition prevail in the use of the furnace? I could not secure a furnace with sufficient radiating surface, without getting nearly double the grate surface necessary; no one would guarantee their furnace to heat air at the desired velocity; I was advised that natural law determined the velocity at which air

could absorb heat, that I could not circumvent or improve on nature; in short the various conflicting opinions and advice offered would make interesting reading as compared with the results obtained; I reasoned that the same natural laws that governed the heating of air passing over the steam coils at a velocity of 1000 feet per minute would apply; that air would absorb more heat in passing over a properly constructed furnace on account of the higher temperature.

Manufacturers of the best furnaces considered, estimated that not less than four to six furnaces would be required to do the work and then doubted the results.