Hot water storage is now generally provided by a copper cylinder. These vary in capacity from 74 to 450 litres – a bath – full is equivalent to about 90 litres – and must conform to BS 699. There are special cylinders on the market that incorporate their own cold water header tank for filling larger baths, which can be useful where no tank already exists or for flats where one may want to avoid having several supplies from tanks in the roof. The placement of the hot water cylinder is important, whether in the bathroom or outside it, but even more important is the height of the cold water tank above the highest fitting.
This provides the head of water needed to provide adequate water pressure and is critical in the case of a shower, which will need about 1.5m head for satisfactory operation. lt is worth sitting the hot water cylinder as close as possible to the various draw-off points to save a long wait while water comes through. This will also save fuel. The hot water storage cylinder should be lagged for fuel economy; under the latest Building Regulations 75mm of the insulating quilt is required. Even better, perhaps, are the specially insulated hot water cylinders that are sold completely. It is extremely convenient to have an electrical immersion heater fitted to the storage cylinder, either as a primary or secondary method of water heating.
