This section is from the book "The Principles And Practice Of Modern House-Construction", by G. Lister Sutcliffe. Also available from Amazon: How Your House Works: A Visual Guide to Understanding & Maintaining Your Home.
I have entered at some length into a description of Messrs. Korting Bro-special system, because I consider that their method of dealing with the air and condensed water is extremely ingenious. In examining steam-heating plants. one observes constantly that the air-cocks are placed at the top of the radiator coils, either through carelessness, or because the designers do not realize that air is heavier than steam; the result is that air-cocks are opened, and steam is seen escaping, and they are at once shut upon the assumption that no air is present in the coil. The heating is not found very satisfactory, the reason being that there is always a stagnant body of air at the lower part of each radiator, and this is very difficult to heat to the temperature of the steam. Quite elaborate arrangement of pumps are also provided in order to get the condensed water back into the boiler, although, as already pointed out in describing this system, the whole of this work can be done by gravitation if the scheme is only properly designed.
Messrs. Korting Bros, also state that, for their low-pressure steam-heating, they use as far as possible radiators which, according to their blest invention, are not filled with steam alone, but with a mixture of air and steam. Formerly when the steam was admitted to the top of the radiator, it pushed the air partially or entirely out, but steam being lighter than air, the result was that, when not worked to their full capacity, the top of the radiator was actually heated to the full temperature of the strain, while the bottom being full of air, remained cool. Now the steam is admitted by a special arrangement to the bottom, and the steam and air rise and circulate through the radiator, warming the whole of the surface to a lower or higher temperature according to the temporary requirements. The inventors of the system claim that the radiators, although wanned by steam, give the same agreeable heat as low-pressure warm-water coils, without having the disadvantages of that system, and especiallv without the disadvantages of freezing in winter. Of course the steam-pipcs are relatively smaller than hot-water pipes calculated to do the same work, and therefore cost less.
In the chapter on low-pressure hot-water heating, I have described a number of forms of radiators, most of which are equally suitable for steam; the only point to be borne in mind is the position of the air-cock The inlet and outlet pipes for steam will also be smaller, and if stock-pattern radiators are bought, it will be necessary to use a nipple to reduce the size of the opening. Messrs. Korting Bros, make a type of radiator with specially thin gills, which is very cheap, and also gives a very large surface for the radiation of heat. Two varieties are shown in Fig. 553, the square and the oval. These are solidly constructed, but are not of sufficiently artistic appearance to be used in living-rooms without some kind of ornamental case, which may be either of cast iron or wrought.
The inventors of the system, which has here been fully described, lay down the following- principal requirements, which should be fulfilled by a low-pressure steam-heating apparatus, and claim that their apparatus fulfils them: -
(1) There must be complete control of the temperature of the rooms heated. | The coils or radiators ought to be below 212° Fahr. as at higher temperatures the small particles of organic matter, which float in the air in the form of dust, are volatilized when coining into contact with the heating-surface and disagreeable and unhealthy smells result.
(3) The steam generator must be constructed so as to secure continuous and efficient combustion of the fuel, to avoid the inconvenieneing of the neighbourhood by the emission of smoke, and to prevent any formation of clinker in the furnace. Further, there should be no liability of damage to the generator owing to possible neglect
Fig .563 - Views of Korting's Radiator, Square and Oral Patterns.
(4) The consumption of fuel must be automatically regulated to suit the variation in the demands on the heating-surface in the rooms, so that the actual weight of fuel burned in the furnace in a given time is proportionate to the amount of heat passing into the rooms from the heating-surface.
(5) To minimize the attendance, the steam-boiler must have a furnace-hopper of such capacity as to contain fuel sufficient at least for the night, so as to dispense with night attendance, and also to secure that the fuel only needs replenishing at lengthy intervals during the day.
(6) Any portion of the heating-system, which may he liable to exposure to frost, must he quite free from water, when the heating is not in operation.
(7) There must he no liability to mating, either on the inside or the outside of any part of the heating-system.
Lap-welded wrought-iron pipes, of what is known as steam quality should be used, with wrought-iron elbows, tees, bends, 4c, throughout. Cast-iron pipes are not suitable for use with steam. The rapports for the pipes will be of a smaller and simpler kind than those needed for hot-water work, and generally the whole of the pipes will be of smaller size and will he found much easier to run in confined places; these small pipes can readily be taken behind skirting-boards and in other similar posi-tions, where it might he difficult or impossible to fix hot-water pipe
The stop-valves used in this work will require to be of a different type. In preference to the "Peet" valve, I use such a valve as that made by Messrs. Dewrance of London with a renewable seating, and illustrated in Fig. 554; these cocks have a good seating, and will last a very long time. For the smaller sizes, say up to 2 inches, they are made of solid gun-metal, and in a house it is scarcely likely that valves larger than these will be required. For the condensed-water pipes, a valve such as the Peet valve may certainly be used, as it affords a full way, which is of some advantage. The whole object in hot-water work, in fact in water work of any kind, is to afford as full an opening as possible, and to change the direction of flow as little as possible, as change in direction means added friction. For steam, however, a slight change in direction makes no difference, but it is essential to obtain a good seating for the valves. In a low-pressure steam-heating plant, there will be less energy expended in friction in the pipes themselves than in a hot-water apparatus, as in the latter case the medium is a fluid and in the former a gas.
Loose valve attached to end of spindle by a nut.
Seating screwed Into valve body.
Fig 564.- Dewrance'a Renewable Valve.