The Back Boiler Replacement Guide 2021

Back boilers really came into fashion back in the 1960s. They are boilers which are designed to fit behind a living room fireplace in order to save space. 

They are no longer readily available and, if you need to replace yours, an installer will usually recommend that you opt for a replacement boiler fuelled by gas.

There are many different options open to you if this is the case but it can be hard to decide what will work best for your property.

This is why we have created this back boiler replacement guide. In this article, we’ll cover:

• what a back boiler actually is
• why back boilers were popular
• back boilers are plagued by poor energy efficiency
• the hidden dangers of back boilers
• the four options open to you if your back boiler is broken
• the three most popular types of modern boilers
• how to save up to 54% on your new boiler installation

If you’re thinking of replacing your back boiler boiler, it pays to shop around.

You should get a selection of quotes for your property because prices vary considerably from one installation firm to the next.  

We’re HomeSage – and we want to make getting a boiler replacement as easy and seamless as possible.

Simply fill in your details on our form and we will contact 3 or 4 local, trusted and Gas Safe registered boiler installers in your area to contact you directly with a competitive quote. 

You don’t have to go ahead with any of the quotes if you decide against it so there really is nothing to lose and huge savings to be made – up to 54% to be exact!

What is a back boiler?

Heating systems which were designed to fit behind the back of a fireplace or a stove were named back boilers and became popular in 1960s Britain. They heat the water using the energy from the fire in front of it.

They are now fairly dated and no longer manufactured widely.

The main reason back boilers have fallen out of popularity is that they have been hugely overtaken in the technology stakes by modern heating systems such as gas combi boilers.

Back boilers were first designed to be a supplementary heat source – that is not the main source of heat for a household.

Over subsequent decades, they were redeveloped into full hot water and heating systems similar to the popular types of boiler models we are familiar with today. 

Why back boilers were so popular and why they’re now so unpopular

Back boilers quickly rose in popularity in the 60s, 70s and 80s because they were so much smaller than other boilers available at the time.

Back then, boilers were often bigger than our modern-day washing machines or cookers. 

They were also much more affordable for families in standard homes and they had a great deal fewer internal components.

This means that there was much less chance of something going wrong – so homeowners considered them to be a good investment for a property. 

Back boilers have taken a back seat in recent decades purely due to the huge developments in technology that we have seen in the central heating sector.

There are simply many more boilers which are hugely more energy efficient, cost effective and environmentally friendly

People stopped buying them and that’s why back boilers are no longer produced here in the UK. 

It can also be incredibly difficult to source any required spare parts for a faulty back boiler.

This means that most people will now replace their back boiler system if something goes wrong out of necessity. 

Poor energy efficiency from most back boilers

As you would expect, back boilers have a much lower energy efficiency rating than their modern combi boiler counterparts.

Generally, they are only about 78% energy efficient so lose a staggering 22% of energy whilst in operation.

This is a big loss compared to the levels of up to 98% available from some combi boilers today.

Because the UK government has regulations that stipulate all boiler systems must have a minimum of 86% efficiency, back boilers are no longer installed or recommended.

The lower the energy efficiency level of your back boiler, the more it will cost you to run.

By simply replacing your 78% energy efficient back boiler with a new combi boiler, you can save you up to £155 per year not to mention reduce your carbon footprint. 

The dangers of back boilers

Not only are back boilers relatively expensive to run and not very energy efficient, they can also be dangerous in your home especially if they are currently unused.

Even if the boiler is empty and no longer being used to heat your home, there will likely be residual moisture inside.

This internal moisture may heat up if you have the fire on in front of it resulting in internal pressure that can cause an explosion.

This has happened many times over the years and it has caused numerous serious injuries and one fatality.

Installers highly recommended you remove any disused back boilers to avoid such tragic outcomes. 

Other risks possible from disused back boilers include:

• structural damage to your property as the back boiler heats up and regularly expands and contracts and
• corrosion of old pipework emitting harmful gases into your home environment. 

The four top options for back boiler owners on the market

1. Replace with a new back boiler

There is one back boiler still available to buy however it is a discontinued model so there will be a limited supply. 

The Baxi Bermuda BBU HE Boiler is a fully condensing back boiler which has been designed for homeowners looking to replace their old back boiler with a more efficient system.

Installation of this back boiler is easy for engineers as it fits with existing pipework and its compact in size.

It also has a SEDBUK efficiency rating of ‘A’ so you can be sure your heating costs will greatly reduce.

There are a number of decorative options available for this boiler so you can style it to create a warm fireplace setting.

However, it is worth noting that the cost of installation will be higher than a combi boiler and this boiler may only last up to 10 years.

2. Repair your back boiler

If you currently have a back boiler which has stopped working, there are some options available for you to repair it.

However, the older the model is the less likely, it may be to find the necessary parts. 

For older back boilers, most of the main internal parts such as the gas valves and thermostat are still readily available from builders’ merchants.

Your installer may struggle to find a suitable heat exchanger though.

We would recommend speaking with the manufacturer of the back boiler first to find out which parts are still available to buy and from where.

Many of them may advise that you check websites like eBay for the less common components to buy them second hand or reconditioned – just make sure you double check the part number.

A handy trick to find out if it’s worth repairing your back boiler is to speak with an insurance company to check if you can get cover.

If you can, you may be able to get new parts fitted that you have sourced yourself at a lesser cost. 

3. Remove the back boiler and replace with a modern combi boiler

A sound option to reduce your heating costs and improve your environmental footprint is to remove your back boiler entirely and replace it with a modern combi boiler.

However, this isn’t a small job and it comes with costs and temporary inconveniences.

If you opt to replace your back boiler with a combi boiler, you will need to have your fireplace and mantle rebuilt and potentially a section of your floor altered, too.

An installer will have to remove the back boiler and surrounding fireplace.

This means that you may need to get a third party to rebuild this for you whilst the engineer installs the combi boiler in a suitable location.

You will most likely need some new pipework configured and the flue system will also need to be addressed because the back boiler will have used the chimney as its flue pipe. 

As you can imagine, this won’t be an inexpensive project.

However, you can expect the money you spend on replacing an inefficient boiler system will eventually be offset by lower gas bills within a few years.

We would encourage you to consider this as an investment for your property.

You can expect to pay within the region of £3,400 – £4,600 if you choose to replace your back boiler with a combi boiler system.

4. Decommission your back boiler and install a modern combi or regular boiler

Another option you could consider is to put the back boiler out of use but not remove it from your property.

This will save you the mess and fuss of builders and structural changes. 

You need to check with an engineer to see if it’s possible to have the boiler disconnected from the gas mains and safely put out of use without incurring risk of problems occurring as previously mentioned. 

You will still have to pay for an installation company to carry out installing a new boiler.

However, you won’t have the extra cost of removing the old back boiler and surrounding fireplace and mantle. 

If you decide to opt for this choice and providing a Gas Safe engineer has deemed it a safe option, you can expect to pay around £2,900 and £4,100, potentially saving you between £500 and £1,000 compared to removing the system entirely. 

The three modern types of boilers and their advantages

Combi boilers

A combi boiler is the most popular choice of central heating systems in the UK due to their energy efficiency levels and affordable price point.

They are compact in size and are usually wall-hung units.

Their compact size means that most combi boilers can be neatly fitted in a cupboard or under the stairs so you don’t have to compromise on your interior design scheme. 

They are different from traditional and system boilers, which we will discuss below, because they don’t store hot or cold water in a tank for it to use.

Instead, they draw a continuous flow of water from the mains pipe which means you never have to wait for water to heat up.

However, your water pressure may drop for reasons such as someone else using the hot tap or issues with the mains supply. 

Combi boilers are energy efficient because they are designed to make use of the majority of energy they produce for example through the condensation they create in the flue pipe.  

Modern combi boilers are usually around 88% – 98% efficient.

This means they lose very little energy in powering the boiler itself therefore your heating bills will be lower. 

The higher the energy rating your boiler has on a scale of ‘A’ to ‘G’, the lower you will pay to heat your home and keep your hot water flowing.  

Regular boilers

A regular boiler is best for large sized homes which have high hot water demand and plenty of space to store the two tanks needed for the system to work.

Regular boilers are sometimes called traditional or conventional boilers.

They require loft space for a water storage tank as well as considerable space for the boiler itself. The boiler is often housed in an airing cupboard. 

They are effective at heating water for large properties which have a high hot water demand and more than one bathroom where numerous people may be using the hot taps at one time.

They store cool water in the tank in the loft which then feeds the hot water cylinder in the boiler creating a tank of hot water ready to be used.

However, once this water has depleted, you need to wait for more to heat up. 

Regular boilers are often recommended in older properties which have unsuitable or period radiators which wouldn’t be able to handle the water pressure of a system boiler.

System boilers

System boilers are used to heat your water and provide your house with central heating using a closed heating system with an internal hot water storage cylinder. 

Firstly, it draws water from the mains supply, and then heats it using a heat exchanger before it stores it in the boiler itself for your future use.

The problem with system boilers is that if you run out of hot water, you have to wait for it to heat up again. 

This is different to combi boilers which keep a constant flow of hot water coming through the taps and radiators directly from the mains water supply. 

However, system boilers can be used effectively in larger houses or properties that have a high demand for hot water and also homes that are located in areas of low water pressure.

Getting yourself the best boiler deals

Getting a new boiler is a big investment for any household particularly if you want to replace an aging back boiler.

Fill in the form at the top of the page and we’ll contact three to four local Gas Safe installers to quote you.

Many HomeSage users have reported to us a difference of up to 54% between their highest and lowest quotes so it always pays to shop around.

Our service is free and you’re not obliged to accept any offer made by one of our partner installers.