Galvanised iron boilers are sometimes used, but the same remarks apply as are given respecting galvanised pipes.
The best size of tube for ordinary domestic purposes is 1¼ in. internal diameter for the circulation and 1 in. for the major portion of the draw-off services; ¾ in. may be used for minor purposes, as lavatory draw-off, &c. There are, however, many apparatuses being fitted at the present moment with 1 in. circulation and ¾ and ½ in. draw-offs, and even ¾ in. circulations are to be met with; but the advantage of a good-sized pipe is the freer flow of water when taps are opened, and most important its less liability of being stopped or rendered unfit for use by incrustation; 1¼ in. tube has fully 30 per cent. more inner surface than 1 in., so that it would take a third longer time to get a ¼ in. coating of deposit in a 1¼ in. tube than it would in a 1 in., and when this thickness has accumulated, the 1 in. tube requires renewing, whereas the 1¼ in. is fit for still further service, so that it can be calculated that 1¼ in. tube will last about double as long as 1 in. so far as incrustation is concerned, and this incrustation, as the reader now knows, is an important element requiring every consideration in almost all districts.
When circulating pipes have to be carried round angles, bends (which are nearly a segment of a circle) should be used invariably, and not elbows, unless absolutely necessary in rare instances. A bend permits the water to circulate round the angle much more freely than an elbow, as the turn in the latter is abrupt, and tends to check the circulation; this only applies to the circulating pipes; it should also be seen that connecting-pieces known as “connectors” are inserted at intervals where they will be of practical use, as they permit of a piece of pipe being removed without disconnecting the whole service, as is so often necessary for a small repair or inspection. A connector is a piece of the tube with the socket so arranged that it performs the function of a union.
When an apparatus is being fitted up, it must be borne in mind that the most perfect arrangement would be to place the tank immediately over the boiler, and carry the pipes in a vertical line between them; this can rarely, in fact, never be done, so it should be arranged and carried in a manner as near this as possible; every angle and every piece of horizontal pipe is objectionable, but regard must be had for positions where the pipes or casings would be unsightly. Where pipes must be run laterally, they should if possible be given a rise towards the cylinder or tank if only 1 in. in 5 ft., but more if possible; these remarks only apply to circulating pipes.
The “flow” pipe should always proceed from the top of the boiler, never from the sides or back (although this is often done), as it will be understood that the heated water, wanting to rise, much objects to starting along a horizontal pipe however short, and another reason is that an air chamber will be formed in the top of the boiler, and cause much annoyance already alluded to.
In No. 1 system the cylinder and circulating pipes cannot well be placed in a cold position, but with No. 2 system ingenuity must be exercised to carry the pipes and place the tank in as warm positions as possible near to chimneys and not on outside walls, &c., if possible; it is time well invested to cover the pipes and tank with a non-conducting covering in any case for the reasons already stated. Pipes should on no account be let into the wall and cemented over, as, with the best work, investigation may at some time be needed, and this would necessitate serious damage to the decoration of the wall in question. On no account sanction the idea of carrying circulating pipes outside the building, however well or carefully they are to be cased or covered. These remarks apply also to the cold-supply pipe to prevent failure in supply by frost. It is also necessary to see that neither circulating pipe comes in contact with a cold-water pipe or a soil (w.c.) pipe.
It will be noticed in the illustrations that before the cold supply enters the tank or cylinder, it descends below its entrance level a short distance, about 12 in., and rises up to the tank or cylinder; this dip in the pipe is called a “syphon,” and prevents the hot water rising up this pipe, as it must be understood that hot water will not circulate downwards.
The cold supply is usually of lead pipe ¾ in. internal diameter, but lead pipe is quite unsuited for soft or pure water (distilled). The same applies to lead cisterns, as this water attacks (oxidises) lead vigorously, and lead pipe is not looked upon with favour for many reasons. Iron is now often used for the whole apparatus, including cistern, tank, &c. (excepting where copper is used for boiler or cylinder). There is a marked advantage if the cold-supply pipe is 1 in. instead of ¾ in., for this reason, if two or three ¾ in. (usual size) taps are opened at once, as commonly occurs, the flow of water must be reduced at each of them if only a ¾ in. supply exists.
The advantages of draw-off services being “returned” have already been explained, and cocks or taps have been treated upon. There are numberless good cocks in the market, but of course the best are subject to wear and tear; those with lever handles, known as plug cocks, have to have the plugs reground in occasionally, and with the screw-down cocks the sealing, generally of prepared indiarubber, has to be renewed periodically; but money is well invested in really good quality taps.
If after the apparatus is fitted and finished there are any leaks noticeable, the purchaser should insist upon these being remedied before the workmen finally leave; there is a common saying amongst workmen that small leaks or “weeps” pick themselves up, i.e. the aperture rusts up; very small leaks will pick themselves up sometimes, but no reliance can be placed in this unworkmanlike way of finishing, and it is commonly necessary to have the men in the house a second time to remedy one or more obdurate “weeps,” which are really defective joints.