A pressurized cylinder or an unvented cylinder is a fairly new technology. It is basically a pressurized hot water cylinder where your hot water is stored. It is usually heated by your boiler and has a back up electric immersion heater. It’s fitted with a system boiler and the tank comes in various sizes from 120 litres up to 300 litres.
The main advantage with pressurized cylinders is the water pressure is high and no pumps are required. Also, there is no need for tanks in the loft, so a loft conversion can be done without the issue of tanks in the way, and the water pressure is fine all over the home.
Pressurized cylinders are very efficient and have a good recovery time once used. They very rarely fail and are essential if you have more than two bathrooms as a combination boiler will struggle with water flow in a house with multiple bathrooms.
A pressurised boiler will remoive the need for any tanks in the loft, and therefore is an ideal solution to clear the space in your loft.