Book - School of Science and Technology

Water systems ± piping arrangements 153ARadiatorsBBoilerRadiatorsFigure 6.6 A simple single-pipe hot water circuitRadiatorsBoilerFigure 6.7 Multiple single-pipe hot water circuits in parallelwould fall by an average of 1 K after each radiator and thus the mean temperature of thefirst and the last would be 72.5 C and 63.5 C, respectively.The number of radiators which may be served by a single pipe is necessarily limited andthus a number of parallel circuits must be provided for in a system of any significant size.These may be arranged, as shown in Figure 6.7, either as horizontal pipes in a `ladder'formation or as a series of vertical drops. There is of course an infinite number of ways inwhich parallel circuits of this type may be arranged but it is important to realise that thedirection of flow through the radiators must correspond with that through the single pipe,i.e. it would generally be unworkable to serve radiators from a rising pipe.The example used earlier was abridged by having radiators all of the same size but thecalculations for any such circuits are not so much complex as tedious. They must be made,however, if a successful result is to be achieved. It seems probable that single-pipe circuitsare currently out of favour simply because of failure in the past, by plumbers, to usesimple arithmetic for domestic heating designs.