As the original leak detection company we have been finding central heating leaks for many years, in this article we discuss how central heating systems work. Often people only start looking into central heating problems when the heating stops working, which on most occasions is due to low boiler pressure, or maybe a big leak!

Central heating systems are examples of equipment we take for granted in our homes, until they malfunction or break down, then we start looking looking for technicians to come and fix them.

However, understanding how the system works is very important.  As a property owner or occupant, you have everything to gain by acquainting yourself with the components of central heating systems, how they work, and so on.  As such, you can quickly notice if the system has a problem, you’re also able to explain to the technician the precise hitch that needs to be repaired.

Here is an in-depth illustration of how a central heating system works;

Components of a Central Heating System;


A boiler is the most important component in the central heating system. It burns the natural gas when you switch it on via an electric switch. A valve opens, and the gas gets in the sealed combustion chamber through many small ducts in the boiler. An electric ignition system lights the gas. There is an electric pump inside the boiler that maintains the water flown around the radiators and pipe-work.


A thermostat acts as a thermometer only that it’s automatic and gets turned on by an electric switch. It activates and switches on the electrical circuit when the temperatures drop; switches the circuit off when the temperature rises. In other words, the thermostat starts the boiler when the room is cold and turns it off when the room is warm enough.


Radiators comprise of copper pipes bent close to 20 times to create a larger surface area to transport heat to the room. In a central heating system, each radiator has a screw that turns it on and off.

Thermostatic Valves

Thermostatic valves are fitted into the radiator to offer you more control over the temperatures of each room in the property. They help reduce energy consumption by the boilers, hence lowering your energy utility bills.

Combi boilers

There are open-vented boilers that heat the water stored in the tank; and combi boilers that heat water on demand. A combi boiler has two independent heat exchangers; one supports a pipe through the radiators, while the other carries another pipe through the hot water supply.


Central heating system pipes are often made from plastic or copper and come in different sizes from 8mm to 35 mm in diameter. The standard pipe sizes for domestic central heating systems are 28mm, 15mm, and 22mm.

Expansion Vessel

Expansion vessels are used in a sealed central heating system to regulate the expansion of the radiators and pipes. When water is heated, they enlarge in volume by at least 4%, the expansion vessel takes up the excess water and prevents the system from bursting.

Header tank

The tank is placed in a loft, an “expansion and feed” tank. It feeds the central heating system with water and also stores the hot water when the system overheats.


Often, low boiler pressure is caused by a leak and unless you get a professional find the leak and fix it, you may be tempted to replace your boiler and buy a new one. But wait, it doesn’t have to be that way!

Water Leak Detection Services UK - Leak Detection London
ADI Leak Detection is here for you; our central heating leak detection services are fast, smart, and always reliable. Talk to us today, let’s come and have a look at the entire central heating system, let’s identify the problem and diagnose it there and then. Enjoy quality workmanship from the real pros, at super affordable prices.