Plumbing in an Electric Shower
PLUMBING IN AN ELECTRIC SHOWER
Electrically heated ‘instantaneous’ showers have become increasingly popular in recent years, and are certainly worth considering if you are thinking of installing new shower facilities. This section describes how to fit the shower and run the.
Pros and cons
An electric shower heats mains-pressure cold water as it flows through the body of the unit to give a constant and virtually limitless flow at the shower head. This is obviously an advantage from an economy point of view, since the water is only heated when required, and no heat is wasted in long pipe runs or storage cylinders.
Complete independence from the hot water system also gives plenty of flexibility over positioning — with only a single 15mm pipe from the rising main to connect, electric showers are by far the easiest to plumb in. Unfortunately this advantage is offset to some extent by the need for an independentsupply from the consumer unit. All in all, there are unlikely to be major savings in time and materials over other types.
The other drawback to an electric shower is that it may not be as invigorating — or as hot — as you expect. The flow of water through the head depends on how quickly it can be heated (see below), but even the most powerful models don’t compare too favourably with a properly installed conventional shower. Also, the need to provide the head with a fine spray to make the most of the flow means that a lot of heat can get lost to the air unless the room itself is kept warm.
Hard water facts
"In hard water areas, scale build-up can be a severe problem for electric showers. The way round it is to fit a water softener in the supply branch – either an electromagnetic type, or a dosing unit designed for instantaneous heaters. Details are given in Problem Solver – Descaling a Shower Head.
Note, however, that some electric showers can’t be used with a mains-fitted regenerative salt water softener; check with the supplier before buying."
Electrically heated showers were among the first appliances to take advantage of the microchip, with the result that nearly all models are electronic — many with automatic temperature control.
The main buying consideration is size — in other words, the power of the heater. The smallest showers are rated at 6kW, but 7kW is the practical minimum for a reasonable flow. 8.4kW showers give 20% more flow than 7kW models, but even these only deliver a moderately powerful spray when the incoming Water is coldest.
Electric showers are widely available from DIY superstores and plumbers merchants, and normally come complete with an adjustable shower head and bracket. For plumbing you need:
15mm pipe — choose from copper, plastic or stainless steel.
Matching fittings — push fit, compression or soldered — and pipe clips.
A stopcock to isolate the supply. Pipe insulation, where the pipe runs through the roof space.
Screws and wallplugs etc for fixing the shower unit. You may also need materials for hiding the pipe/cable and making good — see Problem Solver – How to Hide Pipes and Cables in Your Electric Shower.
The Water Byelaws require that shower heads capable of being dangled in a bath or shower tray must have a check valve fitted between the head and the hose. This is available as an optional extra with most showers, but may only be obtainable direct from the makers.
Tools checklist: Wrenches, screwdrivers, electric drill and bits, tools for making good and redecorating.