Unvented Pressurised System Boilers

An unvented cylinder, often referred to as a Megaflo system (a popular brand), is a type of hot water storage system that provides high-pressure hot water directly from the mains water supply. Here are the key features, benefits, and how it works:

1. Mains Pressure: Provides hot water at mains pressure, ensuring strong water flow to all outlets.
   
   
2. No Cold Water Tank: Unlike traditional vented systems, unvented cylinders do not require a cold water storage tank in the loft, making them suitable for homes with limited space.
   
   
3. Insulated Storage: Typically well-insulated to reduce heat loss and improve energy efficiency.
   
   
4. Safety Components: Includes safety features such as pressure relief valves and expansion vessels to manage the pressure within the system.

What is an Unvented Cylinder (often referred to as a Megaflow System)?

Benefits of a System Boiler

1. High Water Pressure: Delivers high-pressure hot water to multiple outlets simultaneously, providing powerful showers and quick-filling baths.
2. Space Saving: Eliminates the need for a loft-based cold water storage tank, freeing up space.
3. Flexible Installation: Can be installed almost anywhere in the home, not limited by the location of a cold water tank.
4. Energy Efficiency: Modern unvented cylinders are well-insulated, reducing heat loss and saving on energy bills.
5. Consistent Temperature: Provides a consistent supply of hot water at a stable temperature.

How Conventional Traditional Boilers Work

1. Direct Mains Connection: The unvented cylinder is directly connected to the mains water supply. Cold water enters the cylinder, where it is heated either by an internal coil connected to a boiler or by electric immersion heaters.
   
   
2. Hot Water Storage: The heated water is stored in the cylinder under pressure.
   
   
3. Pressure Management: An expansion vessel or internal air gap absorbs the expansion of water when it is heated, preventing excessive pressure buildup.
   
   
4. Safety Measures: Pressure relief valves release water if the pressure becomes too high, ensuring safe operation.

Ideal Applications for a System Boiler: 

1. Homes with High Water Demand: Suitable for properties with multiple bathrooms or high simultaneous hot water usage.
   
   
2. Properties without Loft Space: Ideal for homes without the space for a cold water storage tank, such as apartments or converted lofts.
   
   
3. New Builds and Renovations: Perfect for modern homes and renovations where high water pressure is desired.