There are generally two types of system installed within domestic properties across the UK - knowing the type you have is an essential first step in selecting the right type of pump or boosting system to improve water pressure and flow.

Gravity Fed System

Also called a 'Vented System'

Typical features

  • A cold water tank (usually located in the roof space)
  • A vented hot water cylinder (usually located in an 'airing cupboard' on the top floor).
  • The water pressure available is largely due to gravity and is dependant upon the height of the cold water tank above the appliance being used.
  • The water pressure and flow available from the cold water rising main supply will affect the rate at which the cold water tank refills. It will have no effect on the water pressure and flow available from any water using appliance (other than for any cold water taps connected directly to the rising main).
  • Water pressure is greatest on the ground floor and reduced on the upper floors.
  • For a shower on the top floor, the water pressure (static head) may be as little as 0.08 bar!

It is therefore no surprise that this type of system is often referred to as a 'low pressure system'.

Boosting a Gravity (Vented) System

For a Gravity (Vented) 'Low Pressure System' a pump can be installed to increase pressure and flow to an individual shower, the entire bathroom or even the whole house.

If you have poor water pressure or flow from a Gravity (Vented) system, you should consider one of the following pump units:

Mains Pressure System

Also called an 'Unvented System'

Typical features

  • A combination boiler (in smaller properties)
  • A pressurised (unvented) hot water cylinder (in larger properties).
  • The water pressure available is largely dependant upon the mains water pressure in the supply pipe to the property.
  • The water pressure will be best on the ground floor, but the pressure will be reduced on upper floors of the property.
  • On the third or fourth floor of a multi-storey town house the water pressure may be non existent!

This type of system is often referred to as a 'High Pressure System' - even though the pressure available in many cases may be anything but!

Boosting a Mains (Unvented) System

For a Mains (Unvented) 'High Pressure System' a booster pump and/or pressure vessels can be installed directly in line with the rising cold water mains supply, boosting water pressure and flow to the entire property, including the combination boiler or pressurised hot water cylinder system.

To solve problems with poor water pressure and/or water flow in a Mains (Unvented) system, you should consider the following: