We have, however, lost the radiant heat. To utilize this, surround your furnace with absorption plates placed just a sufficient distance away to permit the passage of the necessary volume of air. The material and surface should be such that the powers of absorption and diffusion should practically equal each other. These plates should absorb all of the radiant heat emitted by the furnace, imparting it to the air (which should pass on both sides of the plates) by diffusion; thus by changing the quality or character of this heat, forming a secondary furnace, or what, in electricity, could be called an induced or secondary current.

By this it will be seen that the same results can be secured with the warm air furnace that are with steam-of increasing its capacity by the application of the fan. Thus, one furnace properly constructed and operated may be made to do the work of two. To accomplish this, however, as in the analogous case, means increased work on the part of the apparatus; hence much heavier furnaces are necessary.

To accomplish all this a furnace must be constructed on entirely different lines from those in the market, none of which are properly adapted for use with the fan to secure the best results, although I have secured very satisfactory results with some of the best. I am confident that with a proper apparatus greatly increased results might have been obtained.

Most of the furnaces in the market are constructed on some application of the same principles, generally copies of some predecessor, faults and all.

But little improvement has been made in warm air furnaces since steam and hot water have been introduced. All energy and ingenuity seems to have been spent in their evolution and improvement, the furnace meantime being side-tracked.

These conclusions are based on experimental facts. Many new phrases of natural laws not here referred to have been met, that are scarcely considered in practice, but which are vital to success. There are two schools, one of speculation and one of experiment and observation. In investigating nature and natural laws we cannot safely transcend experience, still we must utilize objects beyond the pale of experience. This borders on speculation, hence they are inter-dependent and neither can or should be ignored.

Many factors enter into the various complex problems, not herein considered, which are essential to success, such as proper fuels and methods of securing more perfect combustion, the conservation of every unit of heat developed, the principles of mechanical propulsion of air, the proper proportioning of ducts, velocities of

air and best methods and location of ventiducts. So many features or subdivisons of the subject suggest themselves that their mere enumeration would make an article and their proper consideration

a tome.

DISCUSSION.

Mr. H. B. Prather:-This subject is one of primary importance to all of us and, as a new field, is attractive, and the cheapness of the required machinery further brings it into prominence. I have made somewhat of a study of these applications and think that great improvement or change from present types, at least in the form of furnace, is necessary in order to secure economical and effective results. No doubt plants of this nature can be installed with success as far as the simple heating and ventilating is concerned, even with present types, as in the plant described, but the economy in fuel consumption and efficiency in heat development and utilization is the vital question and certainly is the question in comparisons with indirect steam or hot water fan systems. Mr. Kramer touches the important point in the statement that, "by actual experience I have ascertained that heat can be extracted more rapidly than generated." There is no doubt but that the absorption by the air of the generated heat direct from the furnace heating surface, and without the intervention of another medium. such as steam or hot water, would naturally seem to be the ideal arrangement, but can such be done with any existing form of furnace heating surface and at the same time obtain proper combustion, or good combustion, of fuel i. e., proper generation of heat? I think not. The great efficiency of indirect steam heating with fans comes undoubtedly from the bringing of cold air with great rapidity into such intimate contact with the heating surface, as is done in the 1-inch pipe. coils usually used with fan heaters, and the corresponding rapid conveyance of the absorbed heat by the air to the spaces to be heated, the air velocities of air passing over the surface in such heaters varying from 1,000 to 4,000 feet per minute and over. The rapid absorption of the heat by the air in such steam heaters does not in any way affect deleteriously or retard the generation of the heat in the boiler, but if we bring the air to be heated as rapidly, or nearly as rapidly, in direct contact with the heat generating source, as in a fan-furnace application, do we not seriously affect the combustion of our fuel, i. e., the heat generated? Certainly such action in the case of a boiler would seriously impair the combustion. In other words, is it not entirely possible that the combination of generating furnace with the absorbent agent, water, and

the transmitting agent, steam, and the necessary adjuncts of steam pipes and steam heating coils, while it does involve more agents and less direct action, is the most efficient and economical heating arrangement? With retarded and improper combustion in the furnace we get uneconomical and incomplete use and therefore waste of fuel. Why is it that with natural gravity systems of furnace heating and ventilating in schools and churches the consumption of fuel is nearly 50 per cent greater than that of natural gravity indirect steam heating plants in similar buildings, and sometimes in excess thereof? An important factor in causing this is undoubtedly the poor combustion of fuel in the furnace. Certainly the use of a furnace of a form analogous, in principle at least, to that of the fan-heater with greatly extended and subdivided surface, bringing the air to be heated in intimate contact with a maximum amount of heating surface, will increase the efficiency of fan-furnace heating combinations, if some advantageous arrangement of heating surface can be used without serious detriment to the heat generation, i. e., the combustion of fuel. This is a serious question and its successful solution with only natural draft in the generating chamber of the furnace is doubtful; possibly the use of artificial or mechanical draft for the assistance of combustion may help overcome the trouble, but this would necessitate draft regulation and complicate the apparatus.

The claim of an advantage in simplicity of details of apparatus, and hence the requirement of much less attention and skilled handling, is not a very well substantiated one. The modern well proportioned steam plant with fan application for buildings of the size for which it is claimed this fan-furnace combination is especially available, with a gravity arrangement for return of condensation to boiler, and with a low pressure (10 to 20 pounds) slow speed (100 to 150 revolutions per minute) automatically governed steam engine running in oil, or a slow speed electric motor, arranged compactly and with automatic thermostatic regulation of air mixing, requires very little more attention or skilled handling, if any, than a fan-furnace combination plant. How about the heating of pastor's study, committee rooms, library, and toilets in churches when the remainder of the building is not in use? Would the furnace be run without the fan for them? Certainly the proportioning of air conduits proper for the best results with fan would not be proper when fan is not in use. In a steam plant direct radiation can be placed in these rooms, and a low fire in the boiler will raise sufficient steam for their use. Then, again, there will be always the serious danger of escaping gases through cracks and

crevices in the furnace shell into the air to be breathed by the people; no such danger arises in a steam fan plant. Such cracks and crevices will be all the more liable to be had with a fan-furnace than with an ordinary gravity furnace, by reason of the greater differences in temperatures and incidental expansions and contractions. Any escaping gases would be rapidly conveyed to the unsuspecting lungs of the breathers of the contaminated air. There is no argument on the "price question," especially as to first cost. The fan-furnace combination would only be a little more expensive than the simple furnace plant, and would be considerably cheaper than a steam fan heating and ventilating plant, with hot and tempered air ducts, automatic regulation, etc. We are all anxious to see forward strides made in the science of heating and ventilating, but it is well to carefully consider results and "weigh them up" critically. A truly successful plant or apparatus must not only simply do its proposed work, but it must do it with the maximum efficiency and economy in heat generation and utilization, with the least possibility of the arising of unpleasant conditions and breakdowns, and with a minimum size of apparatus to do all this with

ease.

Mr. Blackmore:-I would like to ask Mr. Kramer a question or two. I notice in the drawing here given that the air is forced over the furnaces by the fan. I would ask whether the author has ever tried placing the fan on the other side of the furnace and sucking the air, as it were, through the furnace, and if he has made those experiments whether he found any difference in the results and what the extent of the difference was.

Mr. Kramer:-I will explain as briefly as possible. We have tried the fan on both sides of the furnace and the first application of the fan as an exhaust on the furnace raised objections that to my mind were so reasonable that I never gave it second consideration. There is no furnace constructed that will remain air tight after continued use, and to exhaust over the furnace will certainly produce the results Mr. Prather has feared-to exhaust the gases of combustion from the furnace. The proper plan is to maintain the furnace in a plenum chamber. Every crevice in the furnace would then offer the shortest circuit for the air, which would find its way to the flue and act as a check draft on the fire. I have taken a hammer and in a furnace have knocked a hole that you could stick your fist through, put the fan in operation and not a particle of gas or smoke escaped. The result was to check the fire. If the hole is close to the fire it will act as a blast and assist combustion, but if it is back of the fire it will act as a check draft. The

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location of a fan never should be considered but on one side of a furnace.

Mr. Payne: I would like to ask if Mr. Kramer has used both extended and plain surface furnaces and if he has noticed any relative difference between them.

Mr. Kramer:-The furnaces that I used in this one case had extended surfaces probably 50 per cent in excess of plain surface. I have used the ordinary furnaces without any extended surface. In one instance in Connecticut I had a church in which there were placed originally two of the Smith & Anthony largest furnaces. You probably all know what that furnace is. It is a round drum furnace. They originally placed two of these furnaces without any material change in the construction. After some experiment there were substitutions made in the way of adding extended plates or extensions. The extensions, however, were not continuous metal, but were applied afterwards. They did not prove satisfactory. It was necessary to add another furnace to the plant to get desired results. In another church near by they made an improvement in their furnace and added continuous extension plates to their drum with greatly increased results. I have a plant not yet in practical operation in which the plates of the drum are of cast iron studded with pins. I cannot say what the result of that will be, but I know it will far exceed the plain surface. The furnace referred to in my paper had 3-inch vertical extension ribs placed three inches apart. There were no corresponding plates on the inside of the furnace. Consequently the furnace could absorb no more heat than the inner plain surfaces of the exterior plates, while greatly increasing the radiating surfaces. By experiment on another furnace we extended those exterior plates from three to six inches. With all the tests we could make those plates were heated to the farthest limit practically the same amount they were when three inches. We afterwards tried the experiment of adding inside absorbent plates, endeavoring to absorb a corresponding amount of heat and using the continuous interior and exterior plates as conductors. We experimented quite a while on that, but finding it difficult to maintain the combustion we gave it up for the time. We have within two or three days received a communication from a party who has been continuing these experiments, stating that he has succeeded in securing very good results with 12-inch extension plates, both exterior and interior. He does not think it policy to extend them further and he finds that the capacity of his furnace is fully doubled. That does not mean that you can utilize double the units of heat from the same combustion. You must maintain more fire and gen