Back Boiler Fires: How does a back boiler work?

James Elston
Written by James Elston
Updated on 23rd May 2024
Posted on 22nd May 2024
Topic: Boiler Advice
Back Boiler Fires: How does a back boiler work

How Do Back Boiler Fires Work: Are They Any Good?

how does a back boiler work?

Back boiler fires work by heating up a hot water tank or chamber behind a fire. This is now old technology and a very inefficient way of heating water.

Luckily, many types of boilers are available on the market now with energy-efficient technology like FGHR to lower gas bills, but still, now notable households in the UK are using back boilers.

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This guide will inform you on how back boiler fires work in detail.

“Back boilers are no longer allowed to be replaced.”

Over time, it has been losing against modern boilers and since the invention of modern condensing boiler s, many are finding it is time to end the lifetime of back boilers.

We know about back boilers functions, working process, features and cause of extinction etc., and we certainly know about removing back boilers for our customers and upgrading them to an energy efficient hydrogen ready combi boiler (20% blend) to bring them into the 21st century.

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What is a back boiler? 

The back boiler is a very old conventional boiler system, used as the central heating system for heating the whole house and for heating water, placed just beside a fireplace.

energy efficient comb boiler

In the past, they were the most used boiler, and back boilers can be quite messy when taking them out and replacing them with a combi boiler.

In the 1960s, it started getting popularity; in the 1970’s and 1980s, it was able to get to its highest success.

Later, condensing boilers came and started to take the place of a back boiler.

Condensing boilers are more efficient and cost-effective.

As the condensing boiler has appeared, people could find many drawbacks then and felt they needed to change their boilers. Thus the decline of the back boiler had been started and the revolution of energy efficient new gas boilers started

Different types of back boilers

A back boiler heats up your hot water using some sort of fuel. The type of back boiler you have will depend on which fuel sources you have in your home. Here we will take a look at the different types of back boilers you could have.

house with back boiler chimney

As much as a back boiler is capable, it is strongly recommended that unless your boiler uses is cheap or sustainable, you convert to a different type as soon as possible to help keep running costs down and protect the environment.

Gas fire with back boiler behind it

The gas-fired back boiler such as the Baxi Bermuda was a revolutionary boiler back when it first came out and was installed in many homes in the UK.

These gas back boilers were then energy-efficient and a cheaper way of heating your home. Now though with the advancement in technology and the introduction of condensing gas boilers, these are nowhere near as energy-efficient and could be costing you up to £580 more per year to run.

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Coal open fire back boiler

This type of open fire back boiler uses solid coal fuel to heat up hot water which is sent to your hot taps and central heating system. There aren’t that many of this type of back boiler about anymore and coal isn’t the cleanest fuel to burn. They are also very messy and take up lots of upkeep.

viessmann vitodens combi boiler

If your coal first or back boiler breaks then you will also not be able to replace it with another. If coal back boiler with a boiler behind it you could save yourself lots of money by investing in a new A-rated combi boiler and converting your heating system.

Back boiler vs combi boiler 

Back boilers are the oldest and combi boilers are the most modern boilers available on the market today.

In comparison, back boilers are far behind technology-wise over combi boilers.

The back boiler is not money, space or time-saving while combi saves all. You can find out how much do new boilers cost online with our online boiler quote calculator

Back boilers have much less efficiency, and combi boilers are the most efficient among the boilers available today. if you chose a boiler from our best combi boiler range then you will get a condensing boiler that runs at over 90% energy efficiency. When changing from a G-rated back boiler, this means that you can save up to £580 per year on your gas bills.

How do back boiler fires work? 

Back boilers needed to be installed into a fireplace.

After proper installation, back boilers are ready to use to heat hot water and provide heating around the home.

Then the heat exchanger of the boiler system took heat to heat itself; next started to heat the whole heating system or water (it depends on the purposes it is being used for).


The heat exchanger multiplies the heat and back boilers use the heat of a fireplace run by electricity or gas fire.

The cold water comes into the main system from a storage tank, the main system starts to heat the water, and after heating the water to the desired level, a pump delivers the water to the output.

To keep the necessary pressure for all the output channel, it reserves the hot water in a tank or storage.

“Remember back boilers are no longer allowed to be replaced.”

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Disadvantages of back boilers 

disadvantages of back boilers

When people became able to find well-furnished boilers, back boilers failed to keep their necessity to them.

With the development of technology, people are finding many drawbacks or disadvantages of back boilers.

Some of the disadvantages of the back boiler are here to know about it.

  • Higher price: New boilers appear with new technology; people just realised that back boilers demand a higher amount of money to buy it.
  •  Hot water supply capacity: Back boilers are incapable of supplying hot water instantly. It makes delay to supply hot water.
  • Higher installation cost: Back boilers installation is not less expensive like the newer one. Generally, they demand a higher cost to get them installed.
  • More space capturing: Having so many components back boilers generally need more space. Both hot and cold water tanks are needed to work a back boiler. So, they use a larger space.
  • Not suitable for single families: Single families are increasing day by day. Back boilers are not suitable for single families who need only one output channel of water. If they install them, they will need higher cost to buy, install and maintain.
  • Back boiler servicing costs: A back boiler service costs more due to the fact that a gas fire service is required also at the same time.

Can a back boiler explode?

“Back boilers are not as safe as modern boilers.”

Whilst a back boiler can explode, they are fortunately a very rare occurrence. If yo are concerned that your boiler might be overheating or is going to explode then we recommend you get a heating engineer to look at it right away.

Nowadays, experts have found many risks to using a back boiler.

If you have this type of boiler, you need to be more cautious and take suggestions from the heating engineers.

In some cases, like: you are not using your back boiler but did not remove its components.

Your fireplace is also existing beside the boiler, because of the heat and gas being trapped in the weaker pipework, without the flue system an explosion may happen.

Extinction of back boilers 

h2 ready boilers

The government formed some regulations in 2005, in 2008 and later also to restrict the usage of back boilers and to ensure public safety because they are not gas safe.

Though the presence of back boilers in houses is notable still, the decreasing rate is reminding us about the upcoming decline of back boilers is not impossible.

Fill in our contact form for advice on what to do about your back boiler, “remember how important your health and safety is.”

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Written by
James Elston
James Elston Director Of Boiler Central
Posted on: 22nd May 2024
Topic: Boiler Advice

James Elston is our resident boiler replacement and heating expert here at Boiler Central. With over 20 years experience in the boiler installation industry, James ensures that he knows everything there is about our Gas Safe boiler installations, energy saving and home heating solutions. This can be from simply procuring the latest best combi boilers, to reviewing and ensuring that Boiler Central maintains the highest standards across our boiler installation company.

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