How To Plumb In A Shower

Fit a shower as an extra facility in your bathroom, or install it elsewhere to create a new washing area. Either way, nothing comes close to its instantly invigorating spray. This feature looks at what’s involved in plumbing a shower into your existing hot water system.

Not only does a permanently plumbed in shower add significantly to the value of your home, but they’re the most hygienic and refreshing way to wash. Another convincing reason for having a shower is that they are economical to use — a five minute shower uses only a quarter of the water needed for the average bath.

how to plumb in a showerWhatever your reason for wanting a shower, there’s a whole range of types and styles from which you can choose. There are two main options between which to decide first. This article deals with the various ways in which you can fit a permanently installed shower as an extension to your existing hot water system. The other way to go about the job is to fit a self contained electric unit.

Choosing a shower

The simplest type of shower is undoubtedly a rubber push-on hose which is little more than a glorified handspray. This type requires no plumbing but is clumsy to use.

A much better option is a bath/shower You can provide a good shower by filling a shower-only valve (with blue rose) or a bath/ shower mixer unit. Poor water pressure can be improved by fitting a spray booster or a booster pump mixer. This replaces the existing bath taps and has two outlets for the water — one downwards through a single spout into the bath and one upwards to the shower. Changing from one to the other is simply a matter of moving a lever. Bath/shower mixers are sometimes sold complete with a wall bracket or rail for mounting above the bath. These allow the height of the shower to be varied to suit individuals.

Before buying a bath/shower mixer, make sure that it will fit — or can be adapted to fit — the tap holes in your bath.

A third alternative is a shower-only mixer which has its own independent hot and cold water supplies. This type gives a better flow rate than a bath/shower mixer and can be mounted over a bath or in a separate shower cubicle. However, the snag is’that, depending on where you put it, there may be a lot of extra plumbing to do.

Shower-only mixers can have one of three types of control: either two knobs with one to regulate the temperature and one to regulate the flow; or hot and cold taps; or a single control to regulate temperature only.

You can get two designs of shower-only mixers — exposed and concealed. With an ex-posed design, the valve is surface mounted, together with some or all of the connecting pipework; with a concealed design, the pipe-work and valve are hidden.

Shower mixers have either a rigid or flexible hose which is mounted on the wall to either a bracket or rail.

The last option is to fit an electric shower but to do this you will need to have electrical skills. There are several cases where this might be the only option — see Plumbing con-siderations below.

Siting the shower

You have a choice of putting your new shower either over the existing bath, or in a separate cubicle.

The main advantage of installing a shower over a bath is that the plumbing will be simpler — you won’t have to put in a separate waste pipe. On the other hand, if you’re pre-pared to put in the extra pipework, there are several benefits to a separate shower cubicle — chiefly that you can put one anywhere.

Plumbing considerations

For bath/shower mixers and separate shower mixers, there are several requirements which will effect whether you can install them and, if you can, the amount of plumbing that you will have to do.

The hot and cold supplies to the shower must be at the same pressure. With the majority of houses this won’t be a problem since they have a cold water cistern which supplies both the cold taps — apart from the kitchen tap — and the hot water cylinder.

However, you may have a system where the hot water cylinder is supplied from a cistern, but all the cold taps are supplied from the ris-ing main. With this type of plumbing, there’s a good case for installing an instantaneous electric shower directly to the rising main.

The other type of plumbing system you may have is where all the fittings are connected to the rising main, the hot water being supplied by means of a multipoint gas heater. Again this may mean using an electric shower.

The second requirement is that the pressure of water for non- electric showers must be sufficient to give a decent flow of water, about 5 litres per minute. The pressure is measured by the ‘head’ of water which is taken as the vertical distance between the shower rose and the bottom of the cold water cistern. The minimum head you need is 1m. If you have an insufficient head, it’s best to install a shower pump to boost the flow.

The third consideration when fitting a shower is safety. If the cold supply to the shower is on the same pipe run as other fit- tings, the cold supply will be affected when the other fittings are used. This can mean the person using the shower could get scalded

Water supplies can be taken from the cold cistern and the hot cylinder. You need at least lm of ‘head’ above the rose for a good shower

when the WC is flushed. The two ways of avoiding this are to provide a new and separ-ate supply pipe for the shower from the cold water cistern; the other is to buy a thermosta-tically controlled shower mixer valve. With this type of mixer the outlet temperature is controlled so that if the pressure on the cold side drops, the hot flow is reduced accord-ingly.

The reverse situation can occur with the hot supply — resulting in the shower running cold when a hot tap is turned on somewhere else in the house. This is annoying rather than dangerous, but can be avoided by making sure that the hot connection to the shower is the first from the pipe leading out of the top of the hot water cylinder, before the take-off to any hot taps.

Additional materials and tools

Apart from the shower fitting itself, which should come complete with instructions and all the nuts and washers you need to install it, you may need certain extra materials.

For a bath/shower mixer, you will certainly want PTFE tape and possibly flexible push-fit tap connectors. For a shower-only mixer, you will want lengths of 15mm flexible piping plus sufficient elbows and T-connectors to complete the supply runs.

You may also use wall plugs, pipe clips and either plaster or filler to make good the installation.

If you decide to incorporate a booster pump into the pipework, you have a choice of fitting two types. One goes between the mixer and the shower spray, while the other is fitted before the mixer to both the hot and cold supply pipes.

To save yourself a lot of extra wiring, it’s best to buy a pump which switches on auto-matically when the shower is used — other- wise you will have to install a ceiling mounted pull-cord switch.

It is possible to buy some pumps which have a built-in trans- former and operate off low voltages — either 12V or 24V. With these, switches can be wall-mounted and within reach of the shower.

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