A guide to showers
Showers
There are many different showers, pumped showers, electric showers, gravity showers, thermostatic, manual, power showers etc, etc.
This is a brief guide to the three most common types of shower, the pumped, instantaneous electric and the bath shower mixer tap.
Power Showers
Any shower that is in some way pumped is often referred to as a power shower. This type of shower will require tank fed cold and hot water supplies. These supplies should feed only the pumped shower and particular care needs to be given to the configuration of the hot supply pipe work to insure there is no ingress of air into the pump. Different manufactures have different ideas as to how this should be done so to avoid warranty problems follow their installation instructions carefully.
Plumbing diagram of a power shower (separate pump)
Click to enlarge
There is a very wide range of separate pumps and suitable shower mixer valves to choose from. Valves can be thermostatic or manual.
It is common practice to place the pump in the airing cupboard as this is an ideal location to connect to the hot water and it is often easy to drop the cold feed to the pump from the roof tank here. Pipe work to the shower mixer valve will have to take the most practical route, often through the loft but it is better run beneath the floor to avoid air lock problems.
Another type of power shower has the valve and pump in one unit that is mounted within the enclosure or above the bath. Hot and cold go directly to these units as does the electrical supply.
Most shower mixer valves are also suitable for connection to gravity systems, combination boilers and un-vented hot water cylinders with out the use of a pump.
Electric Showers
Instantaneous electric showers can provide good performance, especially those of a 9KW rating or more. The plumbing requirements for an electric shower are usually straight forward, although the electrics can be more involved, as a large cable has to be run from the consumer unit to the shower.
Plumbing diagram of an electric shower
Click to enlarge
Instantaneous electric showers require mains cold water at a reasonable pressure but if mains pressure is poor pumped versions are available. These pump water from a cold water storage tank they do not pump directly from the mains.
Bath/Shower Mixer Taps
Probably the simplest form of shower, the bath shower mixer tap is capable of reasonable shower performance provided that both the hot and cold supplies are of equal pressure. They can be used with tank fed gravity supplies, combination boilers and un-vented hot water cylinders.
Plumbing diagram of a bath shower mixer tap (gravity fed)
Click to enlarge
Fitting to a tank fed hot water supply and a mains fed cold supply is possible provided check valves are installed in the supply pipe work. In use, balancing the shower to provide a stable and safe temperature is extremely difficult due to the large difference in pressures.
David Kearns © 2004