Diagrams

The Vented System

 You may already be familiar with a vented system. This is where hot water is heated and then stored in a cylinder located somewhere in the home. Traditionally these cylinders are stored in airing cupboards with a cold-water storage tank located in the loft. 

The storage tank is to supply cold water to the base of the cylinder. When colder water is supplied to the cylinder, hot water rises to the top and is then drawn off. The hot water makes its way through the vent pipes to the hot taps in your home. 

There are two very different types of vented systems. An indirect system uses a heat exchanger in the cylinder itself to heat up the water. This differs from a direct system where the boiler is used to heat up the water before passing it to the cylinder. 

 

The Combination Boiler System

Unlike traditional vented systems, they do not require a cylinder to store hot water. They are designed to give you instantly heated water for your taps and your central heating system. This kind of system can save money as you only heat the water you use. 

A combi-boiler may fire up if the temperature in your home drops below the designated temperature on your thermostat. Once your home reaches that temperature, your boiler will then stop. It can be very efficient in heating your home and reduce your energy bills. 

At its most basic level a combi-boiler works by using a series of control valves. These change direction dependent on what you need hot water for at that time. For example, one moment in can be heating your home and the next it can be providing hot water for your tap. The control valve changes direction from one to another.   

 

High Pressure Systems

Finally, a high-pressure central heating system uses cold water from the mains. This cold water is then heated by the boiler and stored in a water tank ready for use. 

It works slightly differently from the vented system and your home needs to be located within a high-water pressure area.