Basic installation of Showers

A shower may be provided either in connection with a conventional sit-down bath or as a separate facility in its own shower cabinet. There can be few people nowadays who are unaware of the advantages that a shower has to offer. They save both time and money. Five or six showers can be taken with the same amount of hot water-and in scarcely more time—than would be required for one sit-down bath. They are more hygienic and mean less work for the housewife clearing up afterwards. A shower cubicle will be easier and safer for an elderly or disabled person to enter than a sit-down bath.

Where a house is being converted into self-contained flats an independent shower can be provided in any space, on a landing, in a hallway or even under the stairs, where there is a space at least 3ft square. A shower can usually be provided without difficulty in any home with a cylinder storage hot water system. There are however certain, quite specific, design requirements that must be met.

The first is that to ensure safe and efficient mixing, the hot and cold water supplies to the shower must be under equal pressure. With a cylinder storage system the hot water supply will be under pressure from the main cold water storage cistern. The cold supply must therefore also be taken from this cistern.

It is illegal, and impracticable, to connect the hot side of a shower to a hot water supply from a cistern and storage cylinder and to connect the cold side to the rising main. Pressure must be adequate. This depends upon the height of the cold water storage cistern above the shower sprinkler. Best results will be obtained if the base of this cistern is 5ft or more above the sprinkler. However if pipe runs are short with minimal bends a vertical distance of 3ft may be sufficient.

Finally, the cold supply to the shower should be taken in a separate distribution pipe direct from the storage cistern, not as a branch from some other cold water distribution pipe. This is a safety precaution. If the shower cold supply is taken as a branch from another distribution pipe, flushing a w.c. cistern or running a basin cold tap could reduce pressure on the cold side of the shower. Pressure on the hot side would remain constant and serious scalding could result.

The design of some hot and cold water supply systems may make it impossible to comply with all of these requirements. Nevertheless there can be few homes in which it is absolutely impossible to install a shower.

Where the cold water storage cistern is not sufficiently high above the shower sprinkler to provide the minimum 3ft head of pressure the simplest solution is usually to raise the level of the cistern. This may involve moving it from the upper part of an airing cupboard into the roof space or constructing a wooden platform for it above the roof timbers. This cannot be done where there is a ‘packaged plumbing system1 in which the cold water storage cistern and the hot water cylinder comprise one unit. It may be impossible too in flats and ground floor maisonettes where there is no access to the roof space. There are however available electrically operated shower pumps which will effectively boost pressure to the shower sprinkler. These operate on a flow switch and are brought into action when the control valve of the shower is turned on. They do, of course, make an appreciable addition to the cost of the installation.

Where bathroom cold supplies are direct from the main it will be possible, in many cases, to bring the cold supply to the shower from the cistern supplying the hot water cylinder. In some instances though this will have too small a capacity to do more than supply the hot water system. In others, where all hot and cold water supplies are direct from the main, there may be no storage cistern at all. It is under these circumstances that the instantaneous electric shower units that have been developed in recent years can prove invaluable. They need only connection to a mains water supply and a suitable source of electric power to provide an ‘instant shower’.

Apart from electric instantaneous showers, which incorporate their own control valve, all showers need to have some kind of mixing valve to blend the hot and cold water to the bather’s requirements. The bath taps themselves can provide the simplest kind of shower mixer. A portable rubber shower, with push-on tap connectors, can be used to convert any pair of bath taps into a shower mixer. These basic shower kits work perfectly satisfactorily provided that the design requirements already mentioned are met by the hot and cold water systems of the house.

It usually takes considerable adjustment, and some discomfort, before a ‘mixing valve’ of this kind’ produces a stream of water at exactly the temperature required. Better control is achieved with a single unit ‘manual shower mixing valve’ which gives control of the shower temperature and, in some instances, flow control as well, by turning a single control knob. Manual mixers of this kind are installed in most independent shower cabinets and there are over-bath versions available too.

Finally there is the ‘thermostatic shower mixing valve’ which is capable of dealing with fluctuations of pressure in the hot or cold supply pipes and providing a mix of constant temperature. These valves are naturally more expensive. They are particularly useful in hotels, schools and similar institutions where a number of showers are run from single hot and cold water distributing pipes. They are also of value in domestic situations where providing separate distribution pipes from the cold water storage cistern to the shower presents difficulties. Early thermostatic mixing valves needed a considerable head of pressure, perhaps as much as 10ft, to work effectively. There are however present day models that will operate satisfactorily on the minimal 3ft head required by a manual mixing valve.

It should be realised that a thermostatic valve cannot increase pressure on either the hot or the cold supply. It can only reduce the pressure on one side to match that on the other. If therefore, cold water pressure is reduced to a thermostatic valve already operating on minimal head, the shower will simply dry up until pressure is restored.

A shower fitted over a bath needs some means of preventing water from splashing onto the bathroom floor. Plastic shower curtains provide the cheapest means of doing this but glass panels, which may be hinged or detachable, provide a neater and more professional solution. Shower trays may be of ceramic material, of acrylic plastic or of enamelled steel. Waste and trap are fitted and connected to the branch waste pipe in the same way as are those of a bath except that shower trays are not normally fitted with an overflow.

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