In cases where there are no intervening doorways or fireplaces, a 3-inch or 4-inch cast-iron pipe may be arranged, as shown in Fig. 520, page 122. This is fed by a small wrought-iron pipe, and for small bedrooms or basement rooms quite sufficient heat will be obtained at much less expense than if radiators are used. In private houses, it Lb not likely that such an arrangement will be considered suitable, except for servants' rooms.

The low-pressure heating-apparatus for a suburban house is shown in Plates XVIII. and XIX. The vertical type of boiler has been chosen, as it takes up the least room; it is fixed at a level of about 18 inches below the basement floor, in order to allow for the return of certain pipes which are carried below the basement passage The smoke-flue from the boiler consists of an iron tube carried into any convenient flue which can be used. The boiler itself is provided with a multiple pipe for the flow, and a similar pipe for the return, a "multiple pipe" being merely a pipe provided with several branch-outlets. The expansion-tank marked x t in Plate XIX. is placed in the cistern-room, and fed from the cold-water cistern. A pipe descends direct from this cistern to the boiler to provide a constant feed. There is absolutely no danger of explosion,1 as the expansion-cistern is open to the atmosphere through a vapour-pipe carried through the roof, as shown in the plate.

Three distinct loops of heating pipes are provided for this house. The flow-pipe of the first loop , begins at the multiple pipe on the top of the boiler, rises to the oiling of the boiler-house, passes along close under the ceiling of the scullery and kitchen, and rises in the corner of the kitchen through the ground-floor into the drawing-room; there it rises vertically inside a case, passes through the first floor, and rises vertically through bedroom 1 into bedroom 5; in bedroom 5 it is carried along the floor inside a skirting-case, feeding a radiator at the window, then passes alongside the wall in the cistern-room without any casing, and is carried similarly through the lumber-room; thence it descends into the W.C. on the first floor, passes along just above the floor of the bathroom, feeds a radiator in the dressing-room, and is then carried in a skirting-case through bedroom 1, feeding a radiator at the window, descends in a case in the corner of the drawing-room alongside the flow-pipe, and feeds a coil inside a casing carried round the bay-window of the drawing-room, this case being fitted with an open-work front; the pipe then passes along the conservatory, feeding a coil placed below the flower-stands, descends through the ground-floor into the coal-cellar, feeding a radiator in the porch, and passes close to the ceiling through the W.C. into the boiler-house, feeding a radiator in the vestibule, and then passing down is connected to the main return.

1During the winter of 1896 -7, not less than Arte explosions of low -pressure beating boilers occurred, killing one man injuring another, and doing considerable damage to property, end in every case there was an expansion-cistern open to the atmosphere . The pipes were, however, blocked with ice. The statement in the text is true, so long as the water way in all the pipes remains open - En.

The second loop runs as follows:- The flow-pipe begins at the multiple pipe on the top of the boiler, rises to the ceiling. passes across the passage close under the ceiling, across the lower hall, rises through the ground-floor, vertically vertically upwards inside the lift in the maid's pantry, and theme into the box-room on the second floor. The radiator on the landing of the second floor is fed from it, and it is then carried along the floor through the box-room, through bedroom 4, descends to bedroom 2, passes along bedroom 2 in a skirting-casing, feeding a radiator at the window, and thence along the floor of the linen-closet, feeding a radiator on the landing; it descends inside the lift to the maids pantry on the ground-floor, and passes into the dining-room, running in a skirting-case and feeding a radiator at the window; it then descends into the break fast-room, and is carried round two sides in a skirting-case, feeding a radiator at the window; it is afterwards led across the lower hall and passage in a small channel provided with a cover, and feeds a radiator in the lower hall and also one in the hall on the ground-floor.

The third loop runs as follows: - It rises to the ceiling of the l>oiler-house, then running below the ceiling of the passage rises into the library, passing up inside a special casing into bedroom 3, thence into bedroom 6, and passes along the side of this bedroom in a skirting-case, feeding a radiator at the window; it descends in the corner into bedroom 3, feeds a radiator at the window, and descends again into the library, there passes round the window, feeding a coil, and runs in a skirting-case along the wall, and finally descends into the basement and back to the boiler beside the flow-pipe.1

1 Every hot-water warming-apparatus must have a draw-off cock fitted to the boiler, or to the return-pipe near it, in such a manner that all the water throughout the system can be drawn off. The emptying of the pipe*. Ac, is a necessary preliminary before certain repairs and alterations can be executed, and during winter ought to be effected whenever the fire under the boiler is allowed to go out. Allowing the fire to go out and the pipes to remain full of water is the most prolific cause of boiler-explosions. - ED.