A CIRCULAR ON THE War/r\i^ % Ventilation OF School Houses and Churches BY THE MAHONY COMBINATION SYSTEM, STEAM, HOT WATER OR WARM AIR. THE MAHONY WARMING AND VENTILATING ESTABLISHMENT, MANUFACTURERS OF HEATING APPARATUS and CONTRACTORS FOR WARMING and VENTILATING PUBLIC BUILDINGS. M. MAHONY, Proprietor. F. P. SMITH, Superintendent. Troy, N. Y. Digitized by the Internet Archive in 2017 with funding from Columbia University Libraries https://archive.org/details/circularonwarminOOmaho Mahonxj Boiler. ggCT. SELF-FEEDING, DIRECT DRAFT BOILER, FOR STEAM HEATING. § ENTIRELY CAST-IRON. ^jj= FOR DIMENSIONS, POWER, ETC., SEE OTHER SIDE. 1=0 R f SHLE ••• BY t SELF-CONTAINED. REQUIRES NO BRICK SETTING. HAS NO FLUES TO CLEAN. DIMENSIONS, HEATING POWER »s»PRICE LIST OF THE MAHONY STEAM BOILER SELF-FEEDING. WITHOUT JACKET. SIZE OF HEATER. Diameter of Fire- Box. Diameter of Grate. c . ~ QJ §8 Size of Heater Base. O . o.S & ~~~S "si **• Weight of Heater Complete. Heating Power in sq. ft. of surface Direct Radiation. Heating Power in sq. feet of surface Indirect Radiation. Size of Steam Pipe. Size of Return Pipe. Price. Without Jacket. No. 0 inches. 10 inches. 9 inches. 51 inches. 17 x 20 inches. 33 lbs. 500 sq. ft. 100 sq. ft. inches. 1# inches. l $ 50 No. 1 13 nX 47 22 x 27 36 750 175 IX iX 75 No. 2 17 uy 2 55 26 x 31 39 1000 300 200 2 iX 100 No. 3 21 is y 56 29 x 34 40 1400 450 300 2 IX 150 No. 4 25 22 x 59 34 x 40 43 1900 650 450 2 y 2 2 200 No. 5 31 28y 2 68 42 x 50 49 3000 1000 700 3 2^ 250 MAHONY BOILER SELF-FEEDING, RETURN-FLUE BOILER, FOR STEAM HEATING. ■; = ' SIMPLE, EFFICIENT, ThEAP. FOR DIMENSIONS, HEATING POWER^PRICES, SEE OTHER SIDE. FOR + SALE f BY DIMENSIONS, HEATING POWER^PRICE LIST OF 'THE MAHONY STEAM BOILER SELF-FEEDING, WITH RETURN FLUE JACKET, COMPLETE, SIZE OF HEATER. Diameter of Fire-Box. Diameter of Grate. Diameter of Jacket. Height of Boiler. Size of Boiler Base. Height of Water Line from floor. 4 800 200 IX iX 100 No. 2 1? 14 >4 25 4 sy 2 26 x 31 34 1100 350 200 2 1 X 2 130 No. 3 21 18 >4 30 48^4 29 x 34 35 1450 500 300 2 IX 190 No. 4 25 ny 2 35 oiy 2 34 x 40 38 % 2000 700 450 2X 2 250 No. 5 31 00 41 60 42 x 50 45 y 2 3200 1000 700 i 3 2y 2 300 Large Fire Surface. Small Consumption of Fuel. Vertical Flues. Easily Cleaned. Requires no Brick Setting. SELF-FEEDING, RETURN FLUE BOILER, Fop Hot ILfatep Heating. IS NOT A SECTIONAL BOILER 51 AND CANNOT LEAK. FOR + SHLE BY It SEE OTHER SXEE. DIMENSIONS, HEATING POWER^PRICE LIST or" THE Mahony Hot Water Heater SELF-FEEDING, WITH RETURN FLUE JACKET, COMPLETE. SIZE OF HEATER. Diameter of Fire-Box. Diameter of Grate. o iJ aJ £ s«, Q O . o Si Size of Heater Base. o § O £ Cl O btP T oJ Weight < >1 Heater Complete. Heating Power in sq. ft. of surface Heating Power in feet of One Inch Pipe. Price with Return Flue Jacket. No. 0 inches. 10 inches. 9 inches. 17 inches. 51 inches. 17 x 20 inches. ny 2 Ibs. 550 sq. ft. 200 lin. ft. 600 $ 60 No. 1 13 11^ 20 47 22 x 27 uy 2 850 300 900 90 No. 2 17 14J4 25 55 26 x 31 16/4 1200 500 1500 120 No. 3 21 isy 2 30 5G 29 x 34 17 1700 800 240.0 180 No. 4 25 22 y 2 35 59 34 x 40 18 }4 2450 1000 3000 240 No. 5 31 28 y 2 41 68 42 x 50 21 3900 1700 5100 290 Self-Contained. Requires no Brick Setting. Has no Joints to become Leaky. Vertical Flue. Cannot become Clogged with Soot. MAHONY BOILER : IS HOT A SECTIONAL BOILER h .. . r SELF-FEEDING, DIRECT-DRAFT BOILER, Fop Hoi 1 ILfater Healing. e< FOR DIMENSIONS, HEATING POWER^PRICES, SEE OTHER SIDE. f< FOR ••• SHLE BY DIMENSIONS, HEATING POWER k^PRICE LIST OF THE Mahony Hot Water Heater SELF-FEEDING, DIRECT DRAFT, WITHOUT JACKET. SIZE OF HEATER. Diameter of Fire-Box. Diameter of Grate. o . £ v ~u « •- V Size of Heater Base. Height of Return Opening from floor. Weight of Heater Complete. Heating Power in sq. ft. o( surface Heating Power in feet o/ One Inch Pipe. ai o £ No. 0 inches. 10 inches. 9 inches. 51 inches. 17 x 20 inches. ny 2 lbs. 500 sq. ft. 150 lin. ft 450 $ 40 No. 1 13 n# 47 22 x 27 14 # 800 250 750 65 No. 2 17 14 # __ 00 26 x 31 16# 1100 450 1350 90 No. 3 21 isy 2 56 29 x 34 17 1600 700 2100 140 No. 4r 25 22 # 59 34 x 40 18# 2300 1000 3000 190 No. 5 31 2 sy 2 68 42 x 50 21 3600 1500 4500 240 Self-Contained. Requires no Brick Setting. Has no Joints' to become Leaky. Has no Flues to Clean. MAHONY BOILER SURFACE-BURNING, RETURN FLUE BOILER, FOR WATER HEATING a :a ■ r "fire surface entirely effective. "S FOR DIMENSIONS, HEATING POWER^PRICES, SEE OTHER SIDE. FOR SHLE + BY U 1 DIMENSIONS, HEATING POWER^PRICE LIST CF THE SURFACE-BURNING Mahony Hot Water Heater WITH RETURN-FLUE JACKET. COMPLETE. SIZE OF HEATER. o c B ° u V) v u •- o Height of Heater. Size of Heater Base. tc °5o r 2 . o 'v 2 C Q/ Weight ol Heater Complete. Z °° .. u - S i = * 4 ,— Heating Power in feet of One Inch Pipe. Price. inches. inches. inches. inches. inches. inches. lbs. sq. ft. lin. ft. No. 0 in 9 17 40 17 x 20 12# 550 200 GOO $ 60 No. 1 13 20 41 22 x 27 uy 2 850 330 1000 90 No. 2 17 i±y 2 25 48 >4 20 x 31 icy 1200 GOO 1800 120 No. 3 21 18 ^ 30 4 Sy 29 x 34 17 1700 1000 3000 180 No. 4 25 22 y 2 35 oiy 2 34 x 40 is y 2450 1200 3G00 240 No. 5 31 2sy 41 00 42 x 50 21 3900 2000 6000 a9 ° Small Water Space. Rapid Circulation. Large Fire Surface. Economy of Fuel. Easily Cleaned. PREFACE. The principal purpose of this book is to call the attention of Architects, Boards of Education and Officers of Churches to the apparatus we manufacture, and the systems we use for Warming and Ventilating School Houses and Churches. Our claims for consideration are simply these : We manufacture the apparatus necessary for successfully introducing our systems, and we guarantee that all contracts taken by us shall be filled to the satisfaction of the Architect or other person or persons with whom the contract is made. All responsibility for the success of our work and all risk of failure, or expense entailed by reason of failure of our system to work as represented, is, by express terms of contract, assumed by us. We will undertake the warming and ventilation of all classes of school houses or churches, by either steam, hot zvater, or warm air, or by combination of steam and warm air, or hot water and warm air. It does not make the slightest difference to us, in the matter of profit, which system we use to secure the heat, on which depends the ventilation. We are at liberty, therefore, to correctly state the merits and demerits of each system without fear of prejudicing our own interests. Whatever system may be used for heating, there must be a very large volume of air warmed for ventilating purposes, and, if it is true, as claimed by many, that there is difficulty in heating certain rooms of a building in windy weather with furnaces, it is no less true that there is just as great practical difficulty experienced in 7 >entilating a school house or church where steam or hot water are used. The difficulties are exaggerated in both cases and can be readily overcome by those who understand the cause of the trouble. It is because there are difficulties met with in the introduction of every system, whether it be steam, hot water or warm air, that the work should never be entrusted to persons who have neither the education necessary to enable them to make the requisite calculations for planning a system of ventilation nor the experience on which alone good judgment can be based. We make a specialty of school house ventilation, and whether we understand our work or not, we are willing to make a contract to obtain certain specified results which very few firms care to sign. If we did not know from past experience that we were working on correct principles, we could not afford to assume the responsibility we do when we make our contracts. We desire to correspond with those interested in warming and ventilating school houses and churches. We draw plans and specifications for heating and ventilating buildings, and will furnish the same for a reasonable consideration. No charge will be made for the plans furnished where we are given the contract for performing the work. When the erection of new buildings or the introduction of new heating and ventilating apparatus is contemplated, we shall be glad to call, upon request, to consult with those in charge, concerning the heating and ventilation. Respectfully, THE MAHONY HEATING AND VENTILATING ESTABLISHMENT. THE MAKING OF CONTRACTS for warming and ventilating School-houses and Churches, is too frequently delayed until the contracts for erecting the building have been let, when it is often too late to introduce any system in the best manner, without alterations in plans and consequent annoyance. The contract for the heating and ventilation should be let just as soon as the general plan and size of the building have been decided upon, and the contractor for the work should prepare the plans and specifications for the construction of the necessary chimneys, flues, etc., and these should be included in and become a part of the regular plans and specifications furnished by the architect. How to secure (food results. — Most committees take the course least likely to secure satisfactory results. After the building is otherwise completed it is the frequent, if not general practice, to advertise for bids for the heating and ventilation, with the understanding that the lowest bidder shall receive the con- tract. Each one is generally permitted to furnish what he pleases, the only question the committee are inter- ested in being, “ who will do the job the cheapest.” Thus, stove dealers, tinsmiths, and plumbers are often permitted to compete for the contracts, and their bids are considered, though they may not understand the simplest principles of ventilation, or be in any way fitted to do work requiring education, skill and good judgment. Since the lowest bidder is to get the contract, it is natural that each one should cut out every possible item that can be omitted. The acceptance of the lowest bid under such circumstances means that the cheapest man, the man with the least knowledge or experience, is entrusted with the duty of providing for the health and comfort of hun- dreds of persons, and the committee, instead of securing a system, with all the good points in it, have accept- ed that in which as much as possible has been left out. Surely, it is not to be wondered at, that there are thousands of poorly heated school houses, and almost none which are ventilated. The proper way to proceed , is to have some competent engineer or architect specify the results to be obtained. Then let those who desire to submit proposals for doing the work, specify the exact apparatus they propose to furnish and explain the system they propose to use. Let it be understood that the contractor must furnish apparatus which will heat the building to 70° F., in any weather, and at the same time, introduce from out-doors and warm a volume of air equal to the cubic contents of the building, as often as every twenty minutes, without causing unpleasant draughts in the rooms, and also expel through the ventilating shaft an amount of air equal to that admitted. Let it be agreed, also, that the architect shall thoroughly test the working of apparatus and system, and that it is upon his certificate that payment shall be made for the apparatus furnished. Having received the proposals and heard the explanations of the several bidders, select that system which appears to possess the greatest merits, rather than the cheapest one, and the result will prove the wisdom of the choice. When a building is already erected, and it is desired to introduce new heating and ventilating apparatus, we will make contract direct with the School Board to secure the results specified above. While in all buildings we may not be able to introduce our complete system, we can always secure fair results. 6 VENTI LATION. We wish to state right here, that what we have to write upon this subject is not original. All the princi- ples set forth have been written about and accepted for many years. We have not discovered anything new though we have our own methods of applying what is known and accepted as correct to actual practice. What we mean in practice by a method of good ventilation, is that system which will, without complicated apparatus, maintain within a building a certain standard of purity of the air, by withdrawing that which is vitiated, and supplying its place with pure fresh air, without causing unpleasant draughts through the rooms. We do not contend, as many do, that there is and can be only one correct system, and then modestly claim we are the only ones who can or do use it. There are two general systems, based upon essentially different principles, known as the Plenum and Vacuum methods. The principle upon which the first is based is : that if a given volume of air be forced into a room, under pressure, an equal amount will be forced out. The principle of the second is : that if a certain volume of air be exhausted from a room an equal amount of fresh air will come in to replace it. “Natural Systems.” Both the Plenum and the Vacuum methods are based upon natural laws. Yet neither can properly be called “ natural ” systems. The steam engine is based upon natural principles, yet its work can hardly be said to be performed by natural means. To ventilate a school house or church, it is necessary to lift an immense weight of air in a single day ; in other words, work must be done and force expended, and this work must be done and force obtained by artificial , and not natural methods. There are numerous causes which render the Plenum system difficult of application and uncertain in its results, and we, therefore, confine ourselves to the consideration of the principles of the Vacuum or exhaust method, on which our system is based. The requirements of this method are : ist. A vertical shaft or flue, known as the ventilation shaft, to which each room in the building is con- nected by suitable flues or ducts of proper size and shape. 2nd. A means of creating a vacuum, or exhaust draft, in the vertical shaft. 3rd. Suitable inlets for the pure air. 4th. A means of warming the fresh air. 5th. The proper valves, dampers, etc., for regulating and controlling the system. These requirements just mentioned are agreed upon by all writers as essential to a good system of ventilation, but when the ques- tion of how to put the system into practical operation in the various classes of buildings, differing as they do in size, material, exposure, location and uses, is considered, authorities differ, and the trouble begins. It is very generally admitted that the simplest force for moving the large volume of air necessary is grav- ity. The air in the ventilation shaft is rendered specifically lighter than that in the building by heating it, and is forced upward by the heavier air from the rooms descending and displacing it. But now comes the trouble. If we ask : “Where shall the warm, fresh air be admitted to the rooms ?” one replies, “at the ceiling;” another, “at the floor.” “ At what point should the foul air be withdrawn ? "again one says, “ From the floor, for carbonic acid gas and the exhalations from the body, are one-third heavier than air and settle to the floor.” Another, disputes this, and says, “from the ceiling, for the breath, being warmer than the air of the room, rises.” Do we venture to inquire, “ What is the best method of heating, ” we find no lack of answers. The maker of steam heating apparatus assures us that “Furnaces burn the air,” “destroy the oxygen,” “leak gas,” “ give a dry heat,” “ will not work in windy weather,” and much more of the same sort. The furnace men first have it out among themselves, over the question of material. The advocate of “ wrought-iron ” or, “steel-plate,” gravely informs us on “eminent French authority,” that “cast-iron is porous and filled with minute sand holes, and when red-hot, permits the free passage of carbonic acid and other poisonous gases through them. The “ cast-iron ” man retorts on equally good authority, that if “air be brought into contact with red-hot wrought-iron, carbonic oxide, more deadly than carbonic acid, is generated.” Then both unite against their common enemy, steam, and proceed to terrify us with statistics of boiler- explosions. They say, “ steam heating is very expensive to introduce, to keep in repair, and for fuel,” “ steam heating is dangerous to health, because it secures no ventilation.” “Radiant heat will not warm a room evenly,” etc., etc. Our criticism of all this is : that while each may understand his own business, he knows very little about the rival system which he criticises so freely. As an instance of this, we quote from the catalogue of a quite prominent “Warming and Ventilating Company,” who manufacture Hot-Air Furnaces, or “ Air- Warmers,” where this statement appears from the pen of a college “professor”: “ Now heat may manifest itself in two “ ways, viz : as temperature and as expansion ; * * * * if a building is warmed by steam three- “ fifths of the force generated by the burning fuel is consumed in the form of mechanical motion. The “temperature of the steam in the boiler may be 400° or 500° F., but the pipes never indicate over 212 0 . I have “never found it above 190° F. ” The utter absurdity of this, is at once apparent, when it is understood that a temperature of 400° to 500° F., can only be obtained with a corresponding pressure of from 290 lbs. to 350 lbs. on every square inch of interior surface of boiler, pipes and radiators ; while steam heating is usually accom- plished with a pressure of from 5 lbs. to 10 lbs. per square inch ; the “safety-valve” being generally set to “blow-off ” at about 15 lbs. pressure, or a temperature of not over 230° F. There are altogether too many “hobbies” ridden in this field of warming and ventilation. Too many get astride some one fact and ride it to death, the while forgetting or overlooking other equally important conditions which tend to offset or neutralize those they are concentrating the force of their intellect upon. Unbalanced, lop-sided, “systems” are met with everywhere. Ventilating flues are put in buildings and expected to exhaust the air though no heat be applied, and people wonder why the air comes down instead of rising. Or openings are made at the ceiling and surprise is expressed because the rooms cannot be warmed. Others attempt to “ventilate” a room which is heated by direct steam radiation, and wonder why the floors are so cold. All these failures are the result of someone’s “ hobby-riding.” The numerous “systems” which work with reverse action prove the truth of this. We do not consider that it makes any practical difference whether the breath rises or falls, as to the point at which we should exhaust the vitiated air from a room. We know that the fresh warm air which we admit to the room, rises to the ceiling, and that if we were to make an opening there our purest air would at once escape, and there would be no ventilation. Even if the object be to cool off a room, it ought not to be by 8 opening registers at the ceiling, but by shutting off the warm air and admitting the cool air, as provided for in our system of continuous ventilation. Air moves, like any other substance, in obedience to force, and if we exhaust the air from the lower part of a room, as we do in practice by the force of gravity, the pure warm air will descend to replace it. The question of the material — whether wrought or cast-iron — of which a furnace should be constructed is of trifling importance. The principal causes of leakage of gas from furnaces, is the small extent of heat- ing surface and consequent high temperature to which they are raised, and the neglect of the fresh air supply. In the furnace there are two drafts, viz : one up the chimney, the other up the warm air flues. The inner flue is supplied through the grate. The outer flue is intended to be supplied through the fresh air duct, and when that is closed, as it so often is, there is a tendency to fill the vacuum from the fire chamber. The principle is precisely the same as that by which we draw the foul air from a room in our system of ventilation. A furnace should never, and if one of proper size be used, need never, become red-hot. We have already stated that it made no difference to us in the matter of profit, which system we employed for heating the building and the air for ventilation. We now state that it makes little or no difference which system we use to secure the desired results. It must be borne in mind that our work is to both heat and ventilate the building at the same time. The same heat which warms the building will not also perform the wofk of ventilating it. Another thing : We must not secure ventilation at the expense of warmth and comfort, nor must we, as is now generally done, secure the warmth by sacrificing the ventilation and health. We therefore need apparatus which will provide heat, during cold weather, for three distinct purposes, viz.: Heat to warm the building ; heat to warm the fresh air for ventilating purposes, and heat to create the exhaust draft in ventilation shaft. In warm weather we need heat for the latter purpose only The Source of Heat. We manufacture Warm-Air Furnaces, Hot-Water Heaters, Steam Boilers, Combination Warm-Air and Steam Apparatus, and Combination Warm-Air and Hot-Water Heaters. We can therefore take our choice of apparatus for securing heat for the purposes named above. For heating the rooms quickly and with certainty in all weather, we can get nothing which does the work better than steam. , For warming the very large volume of air necessary for ventilation, and for heating the ventilating flue we can get nothing which will do the work better, or with so little trouble as our Warm-Air Furnace. When the fresh air for ventilation is warmed by steam or hot-water, it is done by the system of “ indirect radiation,” or, as we explain in the article on heat, by convection. These indirect radiators are radiators which are placed within fresh air ducts and heat the air as it passes over their surface. The apparatus necessary for perfect control and regulation of this system is quite complicated and much more likely to get out of order than the “ air-warmer,” or furnace which does the same work. Therefore, taking into consid- eration all the advantages and disadvantages of each system, including the cost of introducing and main- taining the apparatus, we unhesitatingly declare in favor of the Warm-Air Furnace over steam for all such buildings as school houses and churches where a large supply of pure air is as necessary as warmth. The best possible system is undoubtedly the one which includes the advantage of both, and leaves out the difficulties, if that were possible. We do not claim to have reached perfection yet, but we have made a long step towards it in our Combination Apparatus. With this we heat the room by direct radiation with steam or hot water, and warm the air, for ven- tdating, with the Air- Warmer. We thereby retain the advantage we possessed with steam, of heating distant rooms with certainty in any weather, and the advantage of the furnace of being able to warm the pure air without complicated apparatus. As before stated, we employ either system which seems best suited to the building we desire to heat and ventilate, guaranteeing and becoming responsible for equally good results with either , provided people are willing to pay for the necessary apparatus. Of the Necessity of Ventilation, we say but little, for people are already becoming convinced of the absolute necessity of providing pure air in the school house if their children are to have strong bodies and active minds. Boards of Health, State Boards of Education and State Legislatures are all urging and compelling the introduction of apparatus which will permit a child to secure an education without its health being ruined. People do not so much need to be told what they want as how to get it. EXPLANATION OF PLATES. For illustrating as clearly as possible the principles on which our system is founded, we have prepared a series of plates. The difficulty of showing the movement, under varied conditions, of a substance like air, which is nearly invisible, will be recognized by the reader, but a little study will, we think, make clear what we wish to show. We represent the heat and warm air by the red tint, the cold and foul air by the blue tint. The arrows indicate the directions of the currents. Plate “A” represents the condition of the air in a room heated exclusively by an open fire-place. It will be seen at a glance, what our fathers learned by long experience, that the room is very unequally warmed. The heating is wholly by direct radiation, and the fire-place is at one side of the room. A large amount of air is going up the chimney and its place must be and is filled with cold air from out-doors, thus causing currents of cold air across the floor. Plate “B” shows the same room, but the fire-place is now used only to exhaust the air from the room while the supply of fresh air to replace that withdrawn, is no longer coming in cold through cracks and crevices, but warm from the furnace. We now have a large volume of warm air which is evenly distributed in all parts of the room. This system is correct in principle and admirable in practice except for the inconvenience of caring for a separate fire in each room. Plate “ C ” shows the effect of an opening near the ceiling on the ventilation of a room, and if the building is warmed by a furnace, on the heating also. Our pure air is coming in warm and rises to the ceiling whence it escapes without having changed the air in the room at all. It will be found impossible to heat the room with warm air if the register be open, and it will therefore be closed, and there is no longer an outlet for the air. This is the present condition of very many buildings with respect to ventilation. Plate “ D ” shows the same room with opening to vent flue at floor. As our warm and pure air can no longer escape until it has reached the lowest part of the room, the ventilating register may be always open and the room will be evenly warmed and thoroughly ventilated. This method is correct and one we frequently use in buildings already constructed. The only possible criticism of this plan is that the air is all withdrawn at one large opening and too strong drafts may be created. 10 Plate “ E ” is used to illustrate several systems. It shows, first, our method of warming and ventilating by warm air from the furnace. It will be noticed that the warm air is admitted at the ceiling instead of the floor. This accords with the true principle, though if the air be admitted at the floor it immediately ascends to the ceiling. By having the warm air admitted at the ceiling a very important difficulty, that of sending warm air to distant rooms, is overcome, for not only is the elevation thereby increased, but the wind can no longer force the warm air back to the furnace. The plate also shows the system of heating the room with steam or hot water by direct radiation and ventilating it by fresh air warmed by the indirect radiators or a furnace. The same plate also serves to illustrate the combination system by which with the same apparatus we generate the steam or heat the water for heating the room and warm the air for ventilating it. This system is correct in principle and has many advantages in practice. Plate “ F ” shows our system complete. l'he warm air for heating and ventilating the room is admitted through the register at ceiling. The foul air is withdrawn through numerous small registers instead of one large one, and carried under the floor to ventilation shaft. By this means an almost uniform temperature is secured in all parts of the room. By the use of furring strips across the floor-joists, as shown in the plate, the free movement of air is permitted in all directions, under the floor. Plate “G” shows a section of the building for the purpose of illustrating our System of Continuous Ventilation. \\ hen Warm-Air Furnaces are used, the warm air for heating is also the fresh air for ventilating. If the room becomes too warm, the register is closed to shut off the heat, and that shuts off the fresh air also. Our system is so arranged that the air supply cannot be shut off, though it can be introduced either warm or cool as desired. Referring to the plate: “A” is the warm air chamber or furnace room ; “ B,” “B ” are the outlets for cool air from the air-ducts; “ D,” “ D,” “ C,” “C” are outlets for the warm air into the flues leading to the several rooms. The temperature of the room is controlled by opening or closing the dampers at “ C,” “ C,” by means of the lever “ S,” which is placed in a convenient location in each room. The damper at left of warm-air chamber “A” is shown closed so that only cool air is admitted to the flue, while that on the right is partially opened, and both warm and cool air are obtained in the proportion ddsired. It will be observed that if the heat be entirely shut off from the school rooms the flues are still open to the air-duct “ D,” and the fresh cool air is drawn in to replace that exhausted by the ventilation shaft. Summer Ventilation is frequently neglected even where some attempt is made to supply fresh air when the furnaces are in use. Our system provides for the admission of cool air during the warm weather without the necessity of opening windows. The Patent Automatic Air-Valve shown at “ E,” is a very important part of the apparatus comprising our system. Simple as it is, it perfectly controls the supply of air required for ventilation and warming. Its great value is due to the fact that it takes out of the hands of the janitor the work requiring the most intelligence and best judgment, and does automatically what the janitor frequently fails to do at all, and never can do as well. By the use of this air- valve, the volume of air admitted is always the same whether it be windy or calm weather. The importance of the air supply is fully shown under the head of “Convection.” This device is fully covered by letters patent. 11 Plate “ H,” is an isometric drawing of basement plan of school house, showing the manner in which we ■use the foul air from the building to serve a very useful purpose before it is finally expelled by the ventilation shaft. The arrows, if carefully followed from the air-duct “h” to ventilation shaft E, will indicate the ■course travelled by the foul air. Entering at the air-duct, the air passes to the warm-air chamber “A,” from which it is distributed through the building, by the flues “a,” “a,” “ b,” “b.” Having passed through the rooms it is withdrawn through the ventilating registers and brought back to the basement into the foul air gathering room, “ B.” From the foul air room “B” the air passes through the openings “e,” “e,” beneath the seats of the privies, and there evaporates all moisture and carries off all odors. This Dry Closet System has been introduced into many school houses by the “ Ruttan-Smead Warming and Ventilating Company,” and is a success. We have simplified and improved upon their methods as they improved upon the methods of others, and we claim for our system great advantage over any yet practically introduced for water-closets or privies. The Smoke Flue is usually built within the ventilation shaft, and when the furnaces are in operation, generally heats the shaft sufficiently without the use of the small furnace which is set at the base of ventilation shaft for use in summer, or when the heat from the chimney is insufficient to secure a strong circulation of fresh air. Plate “ I ” is an isometric drawing of our complete system as introduced into the new school house erected in District No. 4, Johnstown, New York. The drawing shows one end of the building cut away to give a view of the automatic air valve ; the fresh air duct beneath basement floor ; the warm air chamber in which furnaces are to be placed ; the openings for warm and cool air to flues leading to school-rooms ; the foul air flues to dry closets ; the small furnace in foul air room and the ventilation shaft and smoke flue. By following the course travelled by the air as indicated in the cut by the arrows, it will be seen that it enters the building through the automatic air valve, which controls the volume admitted, passes thence to the warm air chamber where it is heated and sent up to the several rooms on first and second floors, where it does its work of warming and ventilating. After serving this purpose, the process of ventilation is continued by withdrawing the air through the numerous small registers placed about the room in the base board, from whence it passes under the floor to the ventilation flues which carry the air back to the basement, where, as previously explained, it is used to evaporate the deposits in the closets before it finally passes to the ventilating shaft and thence out of the building. We thus secure Dy this means a constant current of fresh air through the building, and this action is positive and reliable. If the flues be of proper size and the system properly introduced, there will always be the same positive currents and certain results in any weather if the ventilating shaft is heated. 12 THE MAHONY “AIR-WARMER” OR FURNACE, For school house and church work, is constructed with a view of bringing the largest possible volume of air in contact with the furnace. In constructing a furnace, the following points must not be overlooked : ist. The purpose of the furnace is to warm air. 2nd. Air can be warmed by contact only. 3rd. The volume of air which can be warmed, at the same instant, depends upon the extent of the warm surface with which it can be brought in contact. 4th. There is no practical gain in heating power , while there is a great loss in the quality of the air y from having a very high temperature in the furnace. Dulong records the results of his experiments as follows : “ With radiation the higher the temperature “of the heating surface the greater the proportion of the heat given out for each degree’s difference between “the heated body and the surrounding air.” “ But with convection the yield per degrees difference is for all practical purposes, irrespective of the “ absolute temperature of the heated body, or of the difference of temperature of the heated body and the air “ in contact with it.” “With a radiant body at a clear red heat of 1,015° C, the amount of heat transmitted per meter per hour “is about 300 times that transmitted at ioo° C, and at a white heat of 1,415° C it rises to 4,604 times that “amount.” “ With convection, however, the difference in loss of heat per degree is comparatively slight. Supposing “that with the heated body at o° C, and the air at 15° C, the loss by contact or by radiation were 1, at 250° it “ would be by contact only 1.9, while by radiation it would be as high as 3 ; at 310°, 510°, 1,015° an d I >4 1 5°> “the loss by contact would be 2, 2.3, 2.7 and 2.9 respectively, while by radiation it would be 4, 13, 300 and “4,604 times greater respectively than at 0° 5th. For a given amount of fuel the same amount of heat will be generated by combustion, whether the combustion be slow or rapid. The value of a furnace will therefore depend upon the amount of heat saved and imparted to the air by it compared with that lost through the smoke flue, and the amount of heat saved will depend upon the extent of heating surface, and the rapidity of combustion. •Though a furnace may have considerable extent of surface, it may still be so constructed so that the loss of heat will be great from too rapid combustion. Consideration of these facts proves conclusively that it is not the furnace, which by its “superior construction, concentrates the heat,” nor the one in which an “intense heat can be quickly obtained,” but that which spreads the heat most evenly over the largest extent of surface, which is the superior one. In other words, great extent of heating suface with slow combustion, are the points to be sought for. The cost of fuel necessary to generate the heat in the furnace is a matter of considerable importance since it is a perpetual expense. It frequently occurs that extra money invested in superior heating apparatus will be quickly offset by the fuel saved. The kind of fuel used largely determines its cost of course. Good anthracite coal is generally the best and cheapest fuel to use. 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