Gas Safety Week 2020: How do gas boilers heat your home?

A quick guide to your home central heating

Nearly all of us will have a gas boiler in our homes that provides heating and hot water (22 million of us in the UK do). While we all know that the white box on the wall works its magic to provide us heat, how many of really understand how it works?

While you may be happy to live in blissful ignorance and simply appreciate the lovely hot showers and keeping you toasty in the winter, it is quite interesting to understand the basics of how it works and this can also help to appreciate the areas where it can go wrong.

The history of the gas boiler

While water heating can be traced back to Roman times, thanks to their love of bathing, one of the first domestic gas boilers, called the Geyser, was attributed to Benjamin Waddy in 1868. Unfortunately, it didn’t include a flue or vent so was extremely dangerous and liable to explode.

Many developments followed this over the 20^th century but, in fact, gas boilers did not start to become commonplace until the 1950s and ‘60s. Largely due to the introduction of the Clean Air Act and a desire to move away from solid fuel. The condensing boiler has only gained widespread use since the late 20^th/early 21^st century.

What is central heating?

Central heating is the term we use for a system that heats the whole house, controlled from a single furnace. It means that, rather than going and lighting a fire in every room, which is what they would have done in years gone by, the heat for the whole house can be controlled from a single, central point.

What does the boiler do?

Your boiler is the furnace of the central heating system, and therefore the source of heat. In simple terms, it works as follows:

• Natural gas streams into the boiler from a pipe that goes out to a gas main in the street
• Controlled by an electric switch, a valve opens and gas enters a sealed combustion chamber via lots of small jets and an electric ignition sets them alight
• The gas jets play heat onto a heat exchanger connected to a pipe carrying cold water
• The heat exchanger uses the heat energy from the jets and heats the water to around 60°
• An electric pump then pushes the hot water into a circuit of pipe that travels through your whole home, passing through each radiator which it heats as it goes
• Once the water completes the full circuit and reaches the boiler again, it will have lost much of its heat. The boiler then brings it back up to 60° and the process repeats itself

How is the temperature controlled?

The temperature is controlled by a thermostat. This is, essentially, a thermometer with an instruction. It measures the temperature of the room it’s in and if it falls below the temperature you have set it to, it will activate the boiler to heat the radiators. When the temperature rises above the desired setting, it will turn the boiler off again.

When the thermostat is set to a timed programme, it will only do this between the times you have programmed the heating to be on.

Thermostatic radiator valves can also be fitted to individual radiators which give you more control over the temperature in each room.This can help you save money as it means you don’t have to heat rooms that are unoccupied, such as a spare bedroom.

Now, clearly boilers are significantly more complex than this very simplified description here plus only engineers who are Gas Safe registered are legally permitted to work on them so don’t be tempted to have a go yourself! That said, we think it’s really interesting to show how these systems work, especially during Gas Safety Week!

See all the blogs for Gas Safety Week so far here.