Plumbing Advice

Water Pressure Explained

Low pressure gravity system

This is the most common of all domestic water systems. The system consists of a cold water tank (or cistern) normally in your loft & a hot water tank (or cylinder) normally in your airing cupboard. It's called a low pressure gravity system because the water is kept under pressure via the gravity-fed water delivered from the cistern. How much pressure is produced is determined by the height at which the base of the cold water cistern is situated above the outlet. This is typically a minimum height of 1metre for showers. The greater the height of the cistern above the showerhead the more pressure is created.

If you have this system you can install a mixer, pumped digital or all-in-one power shower and you will have get a great showering experience. If you decide on a mixer and want a more forceful shower, fitting a pump will boost the flow rate & pressure even more.

Mains Pressure Combination Boiler

A combination boiler heats cold water direct from the cold mains supply as soon as you turn on the shower or a hot tap in your home. The boiler is normally wall mounted and you won't have a cold water tank (cistern) in your loft or a hot water tank (cylinder) in your airing cupboard. Because the water supply to the system is mains fed this produces a forceful showering experience.

For a powerful showering experience we would recommend fitting a digital or mixer shower to this type of system. Alternatively, for a more gentle flow rate you could use one of Mira's electric shower fitted to the cold mains, this is also an ideal low cost option for a second or en-suite shower room.

Mains Pressure Unvented

An unvented mains pressure system stores mains pressure water in a large strengthened hot water tank (cylinder), usually found in the airing cupboard. The hot water will be heated either by immersion heaters fitted in the side of the cylinder or by a central heating boiler. This type of system doesn't require a cold water tank (cistern) in your loft and provides a high water flow rate & pressure. Other systems also producing hot water at mains pressure are available these are generally known as thermal store systems.

To make the best use of the flow & pressure of these systems we would recommend a digital or mixer shower. Alternatively, for a more gentle flow rate you could use one of Mira's eco mixer showers or fit an electric shower to the cold mains, this is an ideal low cost option for a second or en-suite shower room.

Cold Mains Supply

If you do not have or want to use your stored hot water then an ideal solution is to fit an electric shower to the cold mains supply. The benefit of an electric shower is that it is always ready to use as the water is heated instantaneously within the shower. The amount of hot water flow produced by an electric shower depends on the power rating measured in kilowatts (kW). The higher the kW rating the better the flow.

Most mains water supplies will provide enough pressure to operate an electric shower. In the rare instances that it cannot then Mira has an alternative pumped electric shower. This must be fitted to a cold water tank (cistern) supply and the internal pump will then generate the pressure normally provided by the cold mains.