A pressurised water tank system is a cylinder that provides the home with pressurised hot water.
A pressurised water tank system is a cylinder that supplies pressurised hot water to the home. Unlike traditional gravity-fed tanks, which rely on water from a higher-positioned tank (usually in the loft) to fill the cylinder, pressurized systems do not require gravity. These systems can deliver hot water to all taps throughout the home without needing a secondary tank.
In the UK, there are two main types of pressurised water tank systems: unvented cylinders and thermal store cylinder systems.
What Is an Unvented Cylinder?
An unvented cylinder is a single tank, typically made of copper or stainless steel, that stores hot water for use in your home. The cylinder holds cold water, which is heated and then distributed to your taps. Unvented cylinders come in two varieties: indirect and direct.
What Is an Indirect Unvented Cylinder?
An indirect unvented cylinder connects to your boiler, which heats the water inside the tank. The hot water is then distributed under pressure throughout the home. Most of these systems have an inlet pipe that sends hot water through a spiral coil, transferring heat to the cold water stored in the tank. While indirect systems include immersion heaters as a backup in case the boiler fails, these heaters can be turned off while the boiler is operational.
What Is a Direct Unvented Cylinder?
A direct unvented cylinder relies on immersion heaters to heat the water in the tank, making it a more expensive heating method. This option is typically used in homes with night storage heaters or in areas without gas availability.
Both types of unvented cylinders include expansion vessels or air gaps to manage the increased volume of hot water as it expands. In traditional gravity-fed systems, the higher-positioned tank naturally accommodates this expansion, eliminating the need for a separate expansion vessel.
What Is an Indirect Thermal Store?
An indirect thermal store is a pressurised water tank system that heats the stored water using various heat sources, such as heat pumps, boilers, or solar panels. This system is ideal for homeowners who use gas for heating. It also includes immersion rods as a backup in case other heat sources fail.
What Is a Direct Thermal Store?
A direct thermal store uses immersion heaters to heat the water. It operates similarly to an indirect thermal store, transferring heat from the stored water to incoming cold water. Direct thermal stores are best suited for homes without gas heating and are particularly effective for those using night storage heaters.
Benefits of Installing Pressurised Hot Water Systems:
- Enable the installation of power showers
- Reduced risk of tank freezing
- Faster filling of baths and basins
- Space-saving compared to traditional systems
- Quieter operation, no need for noisy pumps
- Less noise compared to gravity-fed systems
Should I Install a Pressurised System?
The decision to install a pressurised system depends on several factors, including the type of heating system you have, the number of people and bathrooms in your home, and the water flow rate and pressure from your mains water supply.
