Mains pressure hot water heating systems

Mains pressure stored water systems, in general terms, rely on the water pressure within the mains supply to push the water out of the cylinder, through the pipe circuits to the tap or shower outlet.

There are three main categories of mains pressure hot water heating systems:

• Un-vented hot water heating systems
• Direct fired gas water heaters
• Thermal storage water cylinders

The main advantage of this type of system is its high performance, i.e. consistent high flow rates of hot water to all outlets. In addition the un-vented units allow greater flexibility with location as the mains pressure will push hot water up through multi story dwellings to hot water outlets rather than relying on gravity fed systems i.e. cold water storage header tanks, which need to be located above any hot water outlets to push the water out.

The image opposite shows the Redring direct, unvented storage water cylinder which is heated via an immersion heater.

Un-vented hot water heating systems

When an un-vented hot water system is installed both the hot and the cold water supplies within the dwelling, deliver water at the taps or shower outlet at mains water pressure.

Direct fired gas water heaters

A direct gas fired water storage heater is an independent domestic hot water Supply system. Being fed by cold water mains via an un-vented systems kit or it may be tank fed.

Thermal storage water cylinders

A thermal storage water cylinder reverses the indirect water-heating principal. Water that passes through the central heating system and boiler also passes through the cylinder.