Boiler repair

To repair a boiler there are two fundamental types of information you need to understand about your boiler. The first is what your boiler consists of – the components that make up a boiler; the second is the sequence of activity that leads to your boiler working efficiently.

If you understand the components and their tasks, and can identify what action leads to the boiler working efficiently, then you will be far better informed and will be able to make decisions about repairing the boiler when things go wrong.

Dealing with problems

While many malfunctions require professional help, there are some issues that can be dealt with by someone with a fundamental knowledge of how a boiler works. The simplest to understand is a combination boiler or combi.

This is a fairly simple system that works to provide central heating and hot water. What many people don’t know is that a combi boiler only does one thing at a time. It either heats water or provides central heating. A valve, known as a diverter valve will decide which way to send the water, either to the central heating or to provide hot water.

Getting to know your system

Inside the combi boiler there are a number of different components, and it is worth having a look at the manufacturer’s instruction manual to familiarise yourself with how your boiler works and the components within the system. This makes it easier to diagnose problems if they occur – and with a little knowledge, you may be able to identify the problems and make the repairs yourself.

What is the correct sequence of events for a working combi boiler?

It all begins with an action – the central heating is switched on or a tap is turned. This prompts the fan within the boiler unit to kick into action and blow air. In turn this activates the air pressure switch, which then activates the gas valve. These are the three fundamental stages of boiler activity.

A closer look at how things work

The gas valve opens and gas goes into the main heat exchanger. This will then light up (ignite) a flame and via the flame rectification device, the PCB will send out a message to keep the gas going. If the PCB does not send this message then the gas will switch off immediately – this is an inbuilt safety device. Once the flame is lit and the system is working, the water in the boiler heats up.

As it gets hotter the water will turn to steam and expand. The expansion vessel takes up the expansion of the water. If an expansion vessel fails, then another safety device is in place – this is a pressure release valve, which pushes excess water out of the expansion vessel safely.

At it’s simplest, this is how a boiler works. To fully understand what the process involves, take a few minutes to study the manual and identify the process. And if you are in any doubt, contact a professional boiler technician.