"Megaflo cylinders are the choice of architects and plumbers – the system most of them would choose for their own home"
Megaflo is the market-leading brand name of Heatrae Sadia's unvented hot water cylinders. The Megaflo name has become synonomous with unvented cylinders and is often used to refer to unvented cylinders in general!
Whilst the Megaflo is priced at the higher end of the UK market, there are now over 20 other manufacturers offering equivalent models of unvented cylinder. Like the Megaflo, they are also made from high quality duplex stainless steel and typically come with a 25+ year warranty (on the cylinder). Essentially, unvented systems are available for all budgets and to suit individual and specific requirements. The cylinders are generally heated by a gas boiler, electric immersion heater or a renewable heat source, such as solar thermal or heat pumps.
Unvented cylinders store hot water under pressure, and when a hot tap is opened, hot water is forced out by the incoming cold water. There are no cold water storage cisterns, vent pipes or expansion tanks, just high pressure hot and cold supplies direct from the mains.
Without getting too technical, an unvented cylinder relies on the incoming water pressure and flow rates. There are no moving parts and if correctly installed, provides a reliable and efficient hot water system. There are a number of safety devices which are essential to ensure safe operation.
Traditional British domestic hot water systems consist of a hot water cylinder fed from a storage cistern that is vented to
the atmosphere. The flow rate and water pressure is dictated by the vertical distance of the storage cistern above the outlets.
A typically house or bungalow with a storage cistern in the loft, will have a vertical distance of 1 meter from the storage cistern to the shower head. This equates to 0.1 bar pressure.
An Unvented System will typically deliver at least 10 times that pressure for both hot and cold water!
Today, most new homes have Unvented hot water storage systems installed as standard. These are usually connected directly to the cold water mains supply and therefore do not rely on a storage cistern in the loft. The unvented cylinder is sealed to the atmosphere and stores hot water at some pressure above atmospheric. Unvented cylinders provide a highly efficient means of storing and distributing hot water throughout your home.