High Pressure System and Gravity Fed systems

The majority showers and taps need a high pressure of normally 0.5 bar to 1 bar minimum this can only be achieved if you either use a pump or a pressure cylinder.

Combination Boiler or Instantaneous Gas heated System.

A combination boiler will heat your water up as soon as you turn a hot water tap or shower on, the boiler is fed directly from your incoming cold water main and produces hot water at a high pressure of normally between 1 and 5 bar. A combination boiler will also be running your central heating.

Combination boiler

If you have a combination boiler you will not have any hot water storage cylinders just a boiler. If you have a combination boiler you will be able to use any of our taps and showers, low or high pressure devices.

Un-vented High Pressure Systems.

An un-vented hot water storage unit stores hot water under a high pressure within a large cylinder unit, the unit is served directly from the incoming mains cold water and will have a built in expansion vessel or an expansion vessel on top of the unit. If you have an un-vented storage unit you will be able to run any of our taps and showers, low or high pressure devices.

Sealed system (vented DHW).

An un-vented storage unit is a modern cylinder normally white or stainless steel, the key identifier is the cold water storage tank in the roof space. If you think your unit is un-vented but you can still see a tank in the loft double check the tank is redundant, in a lot of cases the tank might have been left redundant in the roof space.

Gravity hot water system

This is a traditional open vented system with gravity fed domestic hot water heating (DHW) and central heating that is pumped around the system. In this traditional open-vented design, the system is fed with water and kept under pressure via gravity-fed water from the main header tank in the loft. The hot water cylinder is heated simply via a gravity hot water circuit from the boiler, and central heating is provided via a separate pumped circuit from the boiler.

A separate header/expansion tank is used to feed the DHW to prevent the risk of contamination with the primary circuit water. If your water pressure is low, you might consider increasing it with a Twin impellar pump