Page:The Amateur's Greenhouse and Conservatory.djvu/27

Rh circulation. It is common in stoves where a moist boat is required to place several feed cisterns over the flow-pipe to promote evaporation. It only needs to here mention that &ldquo;water will find its level&rdquo; to render all these considerations as simple as A B C, and, whether or no, the recognition of this law of nature is the essence of hot-water engineering.

In the adoption of pipes, those of one or two-inch bore are adapted for small houses, and for subsidiary systems in heating parts of houses, such as propagating compartments. But the teachings of experience are all in favour of four-inch pipes for all ordinary purposes, and of two-inch or three-inch pipes for any part of a system where the heat has simply to be conveyed and not diffused, as in the intervals between houses that are heated from the same boiler. In the fitting of the pipes there is nothing so good and cheap as rings of india rubber, which are placed over the end of each length, and then driven with it into the socket. If these are of the right size and the pipes are properly forced home with the rings, &c., there is no occasion for cement or any kind of waterproof stopping. There may be a leakage here and there for a week or so, but it will cease without requiring help, and the joints will keep for a lifetime.

In setting boilers of all kinds the size of the flues must be regulated according to the fuel to be employed. If coal is to be used they should be half a size larger than would be desirable for coke, or they will be soon choked up with soot. The pipes should be laid above the level in all cases, if possible, for if they dip anywhere, as, for example, to pass under a doorway or a path, there will be great loss of heat, and it will be impossible to get up a heat quickly. Have plenty of piping, for there is no economy in a stint. In setting a saddle it is well to place it on a row of fire bricks, to afford more space for fuel. This is especially necessary when the fire has to be made up to last some time. &ldquo;Driving&rdquo; is a detestable practice, and should only be resorted to in emergencies. A large steady fire is far more economical as to consumption of fuel than a small fire with a quick draught, for the stronger the draught the greater the quantity of cold air from without, as well as water within, to be heated. Careful stoking is required for all tubular boilers, on account of the exposure of the tubes to the fire; hence, in a place where things are done roughly, the saddle form is to be preferred.