Your Boiler: The Basics

Although most of us have a boiler in our home, you may not know exactly what type of boiler you have, how it works and how you can help keep it running efficiently.

Taking out Boiler & Central Heating Cover with Home Emergency Assist before a problem develops is important, so you know you’re covered in the event of an emergency, and with a 24/7 emergency helpline and a UK-wide network of qualified engineers, you can be assured your home will be back up and running as quickly as possible.

We’ve put together a handy article to answer any questions you may have about your boiler and heating system.

What is central heating?

Central heating is the system which provides you with warmth from a specific heating source. Your boiler produces a steady supply of hot water which is then pumped around the pipes within your home to fill the radiators you have in every room.

What is a boiler?

The boiler is the most important part of your central heating system as this is what produces the heat. It’s a small furnace which uses gas, oil or LPG (liquified petroleum gas) as fuel. The majority of boilers in the UK are fuelled by natural gas, which feeds through from the national grid. There are different types of boilers too.

How does a gas boiler work?

Typically, there are several pipes entering the boiler. One feeds gas from the mains gas supply (which will come from outside your home) into the boiler. Another pipe enables cold water to enter the boiler so it can be heated, and a further pipe enables hot water to exit the boiler to be pumped around your home.

1. When you turn on your heating, a valve opens which enables gas from the mains supply to enter a sealed chamber inside the boiler. The gas enters and is ignited by an electric ignition switch, which creates blue flames*. These heat a component within your boiler called a heat exchanger, which transfers the heat to the cold water pipe; this will heat up the water to around 60°C.

2. Once the water has been heated, a pump (which is either inside the boiler, or very near to it), will pump the water around a circuit of pipe which runs around your home and passes through your radiators.

3. The hot water enters each radiator, entering at one side and leaving at the other, providing heat for the room.

4. Once the water has travelled around all your radiators, it returns to the boiler. The water will have cooled down by now, so the boiler will reheat the water before sending it around again.

5. While the boiler is burning, it produces waste gases which need to be released outside your home. This is done via a pipe called a flue.

* IMPORTANT: if the flame in your boiler is not blue, i.e., it’s yellow or orange, the boiler isn’t getting enough oxygen. This can be very dangerous and mean that your boiler is emitting a lethal gas called carbon monoxide. This is colourless and odourless but can kill quickly so it’s important to install a carbon monoxide detector in your home.

How do oil and LPG boilers work?

These work in much the same way as a gas boiler. The key difference is that, rather than the fuel being supplied by a national network of pipes, it comes from a tank of fuel which needs to be kept on the property.

Do boilers produce hot water for taps as well as radiators?

This depends on the type of boiler you have, as there are key differences. Many modern boilers work as both a central heating boiler and a water heater for your taps. Others may only be able to supply your central heating.

• Conventional/Traditional Boiler: this will produce hot water for your central heating system but not your taps, bath, and shower. The boiler is fed cold water from a tank in your attic. These are used in combination with a hot water cyclinder in an airing cupboard which will heat and store water for you to use.

• System Boiler: this requires a hot water cylinder to store hot water for your taps, but it’s supplied with cold water from the mains at a high pressure. This means there’s no feed for a tank in the attic.

• Combination (or combi) Boiler: the most common type of boiler installed today. These have two heat exchangers and two hot water pipes. One is connected to your radiators and the other to your taps, bath, and shower. There’s no need to have a feed tank in the attic and as it produces hot water on demand, it doesn’t need a hot water cylinder.

What is a condensing boiler?

In the past, boilers were non-condensing which means that when the fuel burnt, a lot of heat was wasted when gases were released. Wasted heat meant that the boilers would have to work harder, costing you more money and increasing carbon emissions.

Today, all boilers installed must be condensing, which means any waste gases and residual heat pass through the heat exchanger that warm the cold water returning from the radiators before being released via the flue. This helps it to heat up and reduces the work your boiler has to do.

Condensing boilers are far more energy efficient, with over 90% of the energy used being converted into usable heat.

Considering a new boiler?

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To find out more about our Complete Home Emergency plans, boiler and central heating insurance or other types of home care cover plans, such as plumbing and drainage insurance and home appliances cover, contact our friendly team on 0330 09 48 301 or get a quote online.