What exactly is an unvented cylinder?
An Unvented Cylinder is a hot water storage for domestic use which draws water from the cold water mains supply (as opposed to a cold water storage tank) and provides hot water to the dwelling at mains pressure.
As the cylinder is sealed from the atmosphere there is no requirement for a vent pipe and no need for an expansion tank either. Quite simply, to install an unvented cylinder, all that is required is access to the cold water mains supply and a discharge facility for pressure-relief.
Why should I use an unvented cylinder?
As unvented cylinders are supplied by the water mains and not storage fed, they provide hot water at high pressure. The benefit of this is that the pressure is maintained even when several outlets are being fed. In addition to fast filling baths, it will also give the shower that "Power Shower" feeling without the requirement for a pump.
Flexibility, when it comes to locating the unit, is a distinct advantage over the vented cylinders as they can be located generally anywhere in the house as long as there is access to the mains supply and discharge pipe-work to the outdoors can be fitted.
As there is no longer a need for a cistern in the loft, not only is noise reduced significantly but there is no longer a risk of water stagnation. In addition, space is gained from where the tank would have been and frozen pipes in the loft become a thing of the past.
What Heat Sources Work With Unvented Cylinders?
An unvented cylinder can be either heated directly by electricity or indirectly from an auxiliary boiler, typically gas or oil fired, and can be linked to a solar thermal or heat pump installation. By using a dual coil unvented cylinder you can have two fuel sources working independently of each other to maximise energy efficiencies.
When installed with a new generation condensing boiler, as required under the current Building Regulations, and connected to a renewable energy source, CO2 emissions and energy consumption are reduced.
Simple to install, the reduction in pipework means it takes less time to fit than the traditional vented systems. The unvented cylinders come in various sizes and can be made to order in bespoke sizes. As there is no anode the requirement for services is reduced and they tend to have a longer lifespan with many forms offering a guarantee for 25 years.
So, not only are the cylinders highly efficient and reliable but they are highly economical too.
Jamie Stewart is Sales Diretor with McDonald Engineers, one of the UK's leading manufacturers of copper hot water cylinders. Their range features the POWERflow unvented cylinder, THERMflow thermal store and Calorifiers.

Visit the Author's website: http://www.mcdonald-engineers.com