Showers - the choices

When you come to choose a type of shower to fit, you will find a wide range of options and the one to suit you will depend upon the existing plumbing in the building and the people who will use the shower.

This article is intended to outline the basic principles of each type of shower and highlight its advantages and drawbacks.

In order to select the most appropriate type of shower for you, it is important to know the needs of your household and your existing plumbing system.

• If your current plumbing system uses a Combi boiler (i.e. without a hot water tank), some options will be closed to youunless you are willing to undertake a lot of plumbing work.
• If your household is full of teenagers who want to shower morning and night, you may find that a hot water tank based shower system will be unsuitable as it will quickly be drained of hot water.

The options available for showers are fairly wide, so once you know what you need and the plumbing system you have, you should be able to choose a shower system to suit your needs.

Push-on mixer

At the very basic level, the hose with connectors to push onto the bath taps. The temperature of the water is adjusted by the taps. These types of showers will not fit all styles of taps, generally they fit only to taps with round spouts.

Some of these push-on showers are supplied with a wall mounting bracket whilst others are for hand held use only.

Good points:

• Inexpensive.
• Generally no need for additional plumbing.
• Easy to use.

Drawbacks:

• Will not fit all styles of tap.
• The shower needs to be removed if you want to fill the bath by the taps.
• The connections are simple but can easily be dislodged from the taps.
• Temperature control for the shower can be fiddly.

Combined Bath and Shower mixer

A combined mixer tap and shower outlet is fitted to the bath. Normally a knob on the mixer tap switches the outlets to either the taps or the shower outlet. When the outlets are switched to the shower, the taps act to control the shower temperature and flow.

Good points:

• Fairly inexpensive.
• No extra plumbing is needed, just changing the existing taps for the combined mixer.

Drawbacks:

• Temperature control for the shower can be fiddly.

Gravity feed

The water from the cold water header tank and the hot water tank are drawn down under gravity to a mixer for the shower head. The biggest problem can be slow water due to the low water head (i.e. vertical distance between the header tank and the shower head).

A manual or thermostatically regulated mixer can be fitted - see below.

Good points:

• If there is sufficient water head at the bath, it may be possible to plumb into the existing water supplies in the bathroom, but remember you will lose some water head by having an elevated shower head.

Drawbacks:

• Often fairly low water pressure. This can often be improved by raising the cold water header tank.
• The amount of hot water is limited by the size of the hot water tank.

See our article on gravity feed showers.

Power shower

There are three basic types of Pumped Power Showers:

1. Where the pump is included in one unit with the mixer.
2. Where a single impeller pump if fitted between the mixer and the shower head.
3. Where a double impeller pump is fitted into the water supplies from the hot and cold water tanks before the mixer.

In all instances, the water is drawn by the pump from the cold water header tank and the hot water tank and are pumped to the shower head to give an invigorating shower.

A double impeller pump may also be connected to more than one shower and other water outlets (basin, bath etc), depending upon the size of pump, this may mean that only one shower can be used at a time.

With the separate pumps configurations, manual or thermostatically regulated mixer can be fitted - see below.

Good points:

• Increased water pressure for showers - you won't get much better !
• Flow to other outlet (if connected) will be improved.

Drawbacks:

• When plumbing in a Power Shower, large (22mm dia) pipework needs to be taken back to the Cold Water header tank and the Hot Water tank. The pumps use large volumes of water and smaller or shared pipework will affect their efficiency.
• The amount of hot water is limited by the size of the hot water tank, the pump may move 18 litres per minute or more so small tanks mean short showers.
• Because of the volume of water used, the drainage system may need to be adapted.

See our article on power showers.

Combi shower

A Combi shower uses mains cold water and mains pressure hot water heated by the Combi Boiler. Not all Combi Boilers are suitable for connecting direct to the special Combi showers available - if in doubt, check with the Combi Boiler manufacturer.

A manual or thermostatically regulated mixer can be fitted - see below.

Good points:

• Endless hot showers - as the water is heated as needed, there is no limit to the length or frequency of showers (unlike where hot water storage tanks are used).
• Good water pressure - as both hot and cold water are at mains pressure, it should be adequate for a good shower.

Drawbacks:

• The particular Combi boiler you have may not be suitable.
• You probably will have the Combi boiler feeding your bathroom, but you may not have mains cold water - this would require you to run a new supply from the rising main.

Electric shower

An Instantaneous Electric Shower is normally fed from the mains cold water supply, although some may be used via gravity feed providing that there is sufficient water head (typically 10m minimum).

Usually they are designed to operate with a minimum running pressure of 1.0 bar (14.5 lbs per square inch) at a flow rate of 8 litres/minute and a maximum static running pressure of 10 bar (145 lbs per square inch); this may sound confusing but most normal mains water is supplied within these limits but if in doubt, ask a local plumber or the Water Company.

The units normally incorporate the heating element, controls and mixer. The controls usually allow adjustment of the temperature and flow by a knob on the unit.

Good points:

• Endless hot showers - as the water is heated as needed, there is no limit to the length or frequency of showers (unlike where hot water storage tanks are used).
• Good water pressure - as the water supply is usually at mains pressure, it should be adequate for a good shower.
• Some models incorporate a temperature stabilising feature so that the shower water temperature remains unaffected if other taps within the household are used causing the flow to drop.

Drawbacks:

• On some models the flow adjusts the temperature (i.e. high temperatures means less flow and lower temperatures a greater flow).
• The unit must be wired to an electric power supply in accordance with Part P of the Building Regulations so you will need a suitably qualified electrician.

See our article on electric showers.

Different shower mixers

Separate shower mixers are used with most Gravity, Power and Combi showers to control the mix of the hot and cold water supplies to give a temperature and flow comfortable for showering.

The two basic types of shower mixers are 'manual' and 'thermostatic', as the names suggest, the 'manual' type needs to be adjusted by the user to obtain the desired temperature and flow, while the 'thermostatic' type automatically mixes the supplies to give a pre-set temperature no matter what flow rate is selected.

Manual mixer

Both the temperature and flow of the water are controlled by one or, more often, two knobs. The two controls usually work separately so that if you change the flow, the temperature will also change.

Good points:

• Inexpensive and simple.
• The temperature will change if the flow rate varies.

Drawbacks:

• Control can be awkward to obtain the right flow and temperature for different users.

Thermostatic mixer

The control of the temperature and flow are separate. Once the temperature has been set, the flow can be independently adjusted so that even if the flow to the mixer varies, the temperature remains the same.

Good points:

• The controlled temperature makes it extremely easy to use and convenient.
• The thermostatic control means that the temperature and flow of water should not be affected if water is used elsewhere in the property.

Drawbacks:

• They can be expensive.