The Helm System is the invention of Mr. H. Heim, an Austrian, and has been very largely adopted in Austria, Hungary, and other parts of Europe. The system consists of a central heating-apparatus, which is smoke-consuming, and is known as the Calorifer: this heats air brought from the exterior, and the heated air is delivered through specially-formed ducts or flues, prepared in the original design of the building. The same system may, however, be applied to portions of a building, or even to single rooms.

Fig. 493   View of Register and Regulator.

Fig. 493 - View of Register and Regulator.

Fig. 494 .  Section of Duct showing Valvc for Incoming Air.

Fig. 494 .- Section of Duct showing Valvc for Incoming Air.

The arrangement of the Calorifer is shown in figs. 495 to 498. The channel d (figs. 495, 496, and 497) surrounds the grate, and is connected with the outer air, which is admitted and regulated by means of an adjustable valve. This channel introduces heated air under the grate, to ensure perfect combustion. The part of the filling and combution chambers most exposed to the fire is lined with fire-bricks, which are cone-shaped towards the centre at f (figs. 495 and 496), so as to form, together with the cast-iron outer partitions, one channel, which is connected with the outer air similarly to the channel D. The action of this channel is likewise regulated by means of an adjustable valve. Through this channel highly-heated air is brought in contact with the products of combustion, ensuring a complete consumption of the smoke Those parts of the combustion-chamber which are not lined with fire-bricks have smooth. ribbed, or fluted sides, according to the heating-surface required On the uppermost casting of the combustion-chamber there are four nozzles, from which the radiators h (Fig. 496) are suspended freely, to allow for the expansion and contraction of all parts of the Calorifer, and so avoid the straining which causes loose joints and consequent leakage, so usual in other heating-apparatus. Through these radiators, which are also made smooth or ribbed according to the heating-surface required, the products of combustion are taken first downwards at H. and then upwards again through I (Fig. 498), in such a way as to yield the greatest amount of warmth. The smoke-flues k (figs. 495, 496, and 498) are plaeed on the uppermost part of the radiators, and lead to the front of the heating-chamber, whence they are conducted to the cliimuey-flue. The doors l, m, and N serve for feeding the Calorifer, for cleaning out the grate, and for removing the ashes. They are made to be air-tight when closed, and remain closed whilst the apparatus is in action. The covers o (figs. 497 and 498) are for cleaning out the radiators. The warm air is kept sufficiently moist by an evaporating vessel p (figs 495 and 496), which projects through the front partition above the Calorifer, and is provided with an indicator. The front of the apparatus is made of strong sheet-iron, and part of it can easily be removed for the purpose of cleaning the radiators, or for repairs. No brickwork has ever to be disturbed. The calorifers are made in various sizes, and their heating capacity is based upon the calculation of heating from 20° F. external temperature.

Fig. 495.   Vertical Section of Calorifer from Back to Front.

Fig. 495. - Vertical Section of Calorifer from Back to Front.

Fig. 496.   Vertical Section of Calorifer from Side to Side.

Fig. 496. - Vertical Section of Calorifer from Side to Side.

Fig. 497.  Plan of Calorifer.

Fig. 497.- Plan of Calorifer.

This apparatus is intended to he set in a brick chamlier, placed in direct communication with the external air. Some filtering material, such as muslin, can be stretched across the opening, and the heated air passes up the special flues, which must be provided in the building in the same way as for the Smead system. The Heim system differs, however, from that system in having the inlet at a height of about 6 feet above the floor, and in providing two outlet valves into a common flue, one valve being near the floor for winter use, and the other near the ceiling for summer use. A valve is provided in each inlet-flue, by means of which any desired mixture of cold and hot air can be obtained. It will be seen that here there is an attempt to humidify the air, which, I consider, should always be done. In the special pamphlet published by the makers, reference is made to the fart that the Heira apparatus has been fitted in a number of Austrian royal castles. It is, in my opinion, very desirable (if the valves are only arranged to be either full open or quite shut) that some arrangement should be made for connecting the two outlet-valves together, so that one or other most always be open and the other shut; hut if each valve can l>e regulated for partial or full opening, then that is obviously impossible, and the upper valve should be locked during the winter, and the lower one locked during the summer, otherwise both valves may be left open at the same time, when the ventilation will be imperfect and currents will be set up in various directions.

Fig. 406   Vertical Section through Radiator of Calorifer

Fig. 406 - Vertical Section through Radiator of Calorifer.