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Helpful hints

All about showers

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Helpful hints: all about showers

1. Types of showers

The first step in understanding showers, be it for a new installation or replacement is to have some knowledge of the differing types of shower which exist. There is a huge range of showers to choose from but most are one of five shower types.

Electric showers have a cold water only feed and heat and pump the water as it flows through. The heating requires a lot of electricity so a direct separate supply from an electrical consumer unit (fuse box) is required. The cost of electric showers has fallen in the last few years to the extent that in many cases the cost of the shower itself is only around 20% of the overall installation cost.

Power showers are also electric but simply pump the hot & cold supplies, the hot water being heated by the household water heating system. They require only limited electricity and are thus cheaper to install.

Digital showers are are usually a variant of a power shower with a controller in the shower linked to the main apparatus which is in the loft or elsewhere.

Mixer showers run on the hot and cold water supply and need no electricity. They come in two temperature control types, thermostatic and manual and two mounting types, recessed (the body is hidden in the wall) and exposed.

Balancing showers are usually a variant of the mixer shower but unlike regular mixer valves can operate with differing hot and cold water pressure.

Shower pumps. Some showers have a separate optional pump. These are used to pump water to mixer showers, increasing the pressure considerably. They replicate the power shower with the pump in a separate location.

Many people like a lot of water when showering and this is a factor of the flow rate. The table in paragraph two provides a guide to the flow rate from differing shower types.

2. Shower flow rates

Many factors affect shower flow rates, including the flow and temperature of water feeding the property (electric showers), the head of water (mixer showers), valves in the pipes feeding the shower and the shower head. This table provides a general comparative guide.


3. Water pressure and terminology

Water companies have told us the minimum water pressure companies are obliged to supply is typically 1 bar, although many properties have in the region of 2.5 bar. We note the general standards of service published by Ofwat state the minimum is 0.7 bar (7 metres of head). To test the pressure you have coming into your property from the water main fill a gallon container from your cold kitchen tap and time it. If it fills in 30 seconds there is 1.5 bar, 20 seconds and there is 2 bar, any quicker and the pressure will be higher. You can use a smaller container e.g. a kettle and measure the time for 1.5 litres and multiply it by 3.

A typical cold-water flow rate is around 9 litres per minute through a 15mm diameter pipe. Note that this will be reduced if external and / or internal stopcocks or isolating valves are not fully open or are not allowing full flow.

Hot water supply to baths and sinks is often (in older houses) through a gravity-tank fed system, usually located in the roof space. The water pressure from a tank depends on the distance between the bottom of the cold water storage tank and the bath tap or shower head below. Sometimes in flats the cold water storage is immediately above the hot water cylinder around head height. In these circumstances the ‘head’ is minimal and for a shower could be zero.

Many modern houses have pressurised systems so the hot water is at the same pressure as the incoming cold. Gas fed modern flats and small houses typically have a combi boiler, which heats the water as it flows through (like an electric shower) so the hot water is at the same pressure as the cold.

Shower pumps for use with mixer showers typically deliver 1.5, 2 or 3 bars. You should not need (and cannot fit) a power shower or shower pump on a combi boiler or pressurised system. Most shower pumps operate in a ‘positive head’ situation only, meaning the pump outlet is below the cold water storage tanks. ‘Negative head’ shower pumps are required where the pump outlet is at the same level or above the cold water storage tank.

A thermostatic shower reacts to changes in the shower water supply to ensure the water temperature from the shower remains constant.

4. Selecting a shower

When selecting a shower type the first steps are to look at your existing heating system and the proposed location for the shower.

If you have central heating then you will probably want to consider a power or mixer shower. If you have a combi boiler, a standard mixer shower usually works quite well and provides an adequate water flow rate as the both the hot and cold supplies will be at the mains cold water pressure. Remember that shower pumps and power showers cannot be used with combi-boilers.

If getting both hot and cold water to the shower is problematic then consider going electric but do consider that the installation cost for an electric shower is several times the cost of the shower itself.

Showers can be installed in many locations other than bathrooms and are often installed in an annex or bedroom where space is available. There are rules about the how close showers can be to power sockets and this needs to be taken into consideration where the installation is outside a bathroom.

A separate shower cubicle is often fitted, sometimes in place of a bath. There are a wide range of sizes and designs available including cubicles designed for ease of access or to enable a carer to assist. Trays also come in a wide variety of designs, some low level, some needing a step up. Cubicles need connection to drainage and depending on drain runs this can impact the type of tray that it is practical to fit. If drainage runs are difficult waste pumps can assist in many cases. If you are fitting a shower over a bath the wall will need tiling to shower height and a shower screen or curtain fitting. Tiles remain the common choice for shower walls but a range of waterproof panels and tile sheets are also available and increasingly popular. These negate the need to clean grout and are particularly useful in hard water areas.

An extractor fan is also a good idea if you don't already have one and in conversions or new builds is a requirement. These can be fitted in ceilings and walls and in most cases have a 'run-on' timer to ensure condensation is reduced by continuing in operation for a few minutes after the lights have been turned off. Fans that operate based on humidity levels are also available.

If you are planning a shower also think about flooring. It can be forgotten but it provides the finishing touch and should be planned in the general scope of works.

Finally remember that showers require maintenance. Grout and mastic in particular needs maintaining to prevent leaks and it’s a good idea to know where to isolate the water supplies to a shower, just in case an emergency occurs.

For more on showers and illustrations read this.

For more on shower types read this.

And for more on shower repairs click here.

Ask 50plus for help if you are unsure. Only DIY if you are competent and understand the rules. Regulations apply to shower installations.


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