BACK BOILERS -Everything You Need To Know AND MORE!
backboilers
What Is A Back Boiler?
Back boilers are a very old fashioned form of central heating. They are fitted behind a open fire and is hidden from view.
Back boilers were very popular in the 60s and 70s but are gradually being phased out in favour of combis. Baxi Bermuda -Parkray and Rayburn boilers were the main names with this type of heating.
Back boilers came into fashion back in the 1960s which were designed to fit behind a living room fireplace in order to save space.
The open fire would heat the water in a tank behind the fire and this heated water would rise into a cylinder connected to it upstairs which would be used by the home occupants for washing etc.
Whilst many homes still have back boilers as their main source of heating, they are no longer readily available for replacement due to their in efficiency and are usually replaced with a gas combi boiler.
It is very difficult now to replace a back boiler with a similar type as back boilers are no longer manufactured apart from the Baxi Bermuda Condensing Boiler.
PLEASE NOTE FOR SAFETY – If you do upgrade to a combi boiler , we recommend that the old disused back boiler ( in situ behind the fireplace ) should still be removed .
Back Boiler Grants
Did you know there are 100% grants for back boiler replacement ?
What Are Free Back Boiler Grants?
Do you have an old Baxi Bermuda Back Boiler that is currently heating your home? We are offering a Free Conversion To A Combi Boiler if you receive a benefit that is worth in excess of £3000.
The government are now offering 100% FREE grants to remove your old Baxi Bermuda back boiler and replace it with a combi boiler on the wall. The boilers fitted include Ideal – Worcester & Baxi.
As old backboilers are very expensive to run , the Government has allocated millons of £ to help people convert old back boilers to a combi 100% Free Of Charge
This will be a much better option for you than having a backboiler replacement and if you are on a low income, you can get it for free!
This Free Back Boiler Grant scheme is for home owners only.



What Is Included In The Back Boiler Removal Grant?
If you are found to be eligible for this grant you will receive:
- A Brand new combi boiler fitted on the wall
- Your old backboiler capped off and removed from the chimney breast
- All pipe work upgraded and rerouted
- A 2 year Warranty
- A top rated combi boiler fitted
- New controls and programmer
- APPLY BELOW
Need To Replace Your Back boiler?
We recommend you :
- See if you are eligible for a free government grant to replace it with a combi boiler.
- Replace with a new Baxi Bermuda back boiler SEDBUK efficiency rating of ‘A’
- Remove the back boiler and replace with a modern combi boiler privately.
- This will mean that you will need to have your fireplace and mantle rebuilt and potentially a section of your floor altered, too.
Are Back Boilers Still Available To Buy?
Yes 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.
UK government regulations state that all boiler systems must have a minimum of 86% efficiency, so most models of back boilers are no longer manufactured .
The dangers of back boilers.
If you have had your back boiler decommissioned in the past, it is worth getting it completely removed as there have been some issues in the past.
In decommissioned back boilers there will likely be residual moisture inside, which will heat up if you have the fire on in front of it .
This can result in a build-up of internal pressure that can cause an explosion which has caused numerous serious injuries and one fatality.
Installers highly recommended you remove any disused back boilers to avoid such tragic outcomes.
What Is A Back Boiler Unit ?
Back boilers ( known as back boiler units or BBUs) became popular with many households as their main heating source in 1966 with the launch of the original Baxi Bermuda. A back boiler is a small, compact boiler fitted at the back of an open fireplace hearth.
It sits behind a gas fire and provides hot water and central heating to the property. Back boilers were popular until the Building Regulations changed in 2005, when it became a requirement to install high efficiency condensing boilers. Although many have been replaced with wall-hung condensing boilers, there are still a large number of back boilers still installed in UK homes.
An old standard efficiency back boiler is less than 70% efficient – so for every £1 of gas burned, on 70p worth of useable heat is generated and the other 30p worth is lost up the chimney.
By replacing it with a new boiler at over 90% efficient, fuel bills can be reduced by up to £305, according to the Energy Saving Trust.
Back Boiler Replacement & Cost Of A Full Central Heating Installation 2022
The disruption to a property is quite significant which is why it is better to do this work ahead of other refurbishments.
The cost of a full upgrade and installation will be in the region of £4000- £5,000.
This cost assumes an average 3 bed semi home and will include:
- Full removal of the old back boiler
- All Replacement pipework
- 8-10 radiators a 3-4 bedroom property
- A-rated combination boiler 30 Kw

Back Boiler Replacement Cost
Replacing your old back boiler with a combi boiler is likely to be an expensive job, estimated at anything from £3000 onwards. Although this may seem to be a costly expense, you should bear in mind that there are potential savings to be made with a new and energy-efficient combi boiler. Not to mention the quality of heating and hot water that combi systems provide.
The cost of replacing a back boiler is between £2,500 and £4,500. This will depend on which boiler you choose and where to install your new boiler. Back boiler replacement costs so much because you have to thoroughly remove the back boiler and install a completely different boiler elsewhere in your home. This involves a lot of work, especially running new pipework for mains gas and distribution pipework too The most popular replacement is the modern combi boiler which will give you hot water on demand. You should expect the whole job to take 2 – 3 days.
Extra Costs
Replacing a back boiler is a big cost . Plan your install and see if there will be extra charges.
- A system boiler will need a hot water cylinder in the airing cupboard and a cold water storage tank in the loft plus further pipework so will be an extra £1000.
- The location of the boiler can affect the cost especially if in an airing cupboard as the flue will need to exit the roof.
- Choose the size of the boiler
- A combi boiler will also save you from the added cost of having a cold water storage tank in the loft as well as a hot water cylinder in the airing cupboard
Making Good After Back Boiler Removal
Removing a back boiler will cause some damage to the existing hearth and fireplace surround.
You will need to upgrade the fireplace with a new surround and electric or gas fire or use it for a real fire.
Back Boiler Replacement

How Efficient Are Back Boilers?
Back boilers have a much lower energy efficiency rating than their modern combi boiler counterparts. Generally, they are only about 60 -70% energy efficient as compared to the more modern condensing boilers which are over 90% efficient.
This means that an old back boiler will be costing you over 25% more in eating costs.
How Long Does A Back Boiler Conversion Take?
Back boilers are often the most difficult system upgrades to install. Given their location (behind your gas fire), they aren’t easy to remove and the removal is often quite a difficult job and usually quite expensive.
It can be quite a messy job as it can involve the removal of the fireplace and the area around the fire to be able to remove it. In some cases, the back boiler can be decommissioned and left where it is so the disruption is minimised.
Are Back Boilers Dangerous ?
We recommend you remove the back boiler behind your fire if no longer used. Back boilers were often left because of the added expense and disruption involved in their removal. A redundant back boiler can pose a real danger to your home if you don’t remove it, due to its location. Back boiler replacement should be considered now while grants are on.

Possible Hazards Of A Disused Back Boiler
- If the boiler is empty it will collect residual moisture.
If the fuel burner in front of it is still in use, then this will heat up the boiler and create steam. If this boiler is not vented this can create internal pressure which will eventually result in an explosion There are examples of back boilers exploding and causing injury and in one case, even a fatality.
- A disused back boiler can experience corrosion and fracturing of old pipework .
Both can leach harmful gases into the home or they can build to a temperature which creates a fire hazard.
Please remove at your earlist convenience
What happens when you remove a Baxi Back Boiler?
The back boiler, it’s flue and gas fire – all will be removed unless you want to keep the back boiler fireplace.
Removing the gas fireplace and replacing it with an electric fire could cost you more in the short term but less in the long term. This is Quite a messy job and is normal while removing a back boiler.
Back Boiler Removal – What Is The Process?
It’s likely that a back boiler removal will take quite a bit of work as it is positioned behind your fireplace. Typically, the process will include:
- Removing the fireplace
- Removing the back boiler system
- Reconstruction of the mantle space
- Installation of the combi boiler system in an alternative location
- New pipework installed to fit with new combi boiler
- Work to be done on the flue system to suit the combi boiler (the back boiler would have used the chimney).
We recommend you do not do this yourself and employ the services of a Gas safe Registered Engineer. Have two to three empty buckets to hand as dirty water coming out of the boiler can damage your flooring and carpets
- Remove carpets and all the unnecessary things from the room.
- Dust and pieces of brick will be flying around and it would be best to protect your furniture.
- You can place old rugs over the floor to prevent scratching.
- Have one spare bucket to collect pipework waste in.
- Engineers will have to uproot the pipework and there will be a lot of dirty water and limescale present.
Decommissioning a Back Boiler
By decommissioning a back boiler, it won’t actually be removed from behind the fireplace. Decommission effectively means it will disconnect from its source of power/energy. It will remain behind your fireplace gathering dust out of use. To decommission your old back boiler, engineers will need to get behind your fireplace, which means you will likely have some damage to your fireplace and carpet. Prepare to make repairs afterward.
However, decommissioning your back boiler instead of removing and replacing it, will save you money. Savings will depend on who is doing the work and what exactly needs doing. On average, you can expect a boiler decommissioning to cost around £3000. Before making a bold decision, decommissioning might not always be an option. Always speak to one of our Gas Safe heating engineers who will decide whether it can be safely done.

How Long Do Baxi Back Boilers Last
Back boilers usually last for around 25 years, provided they have been well maintained and serviced regularly. Some backboilers, particularly the Baxi Bermuda have been know to last over 40 years as they were well made in the 60s. Indeed there are still many backboilers in the Uk that are still going to this day, albeit they wont be very efficient and will be up to a third more expensive to run. If your old Baxi Bermuda is on its last legs you should bite the bullet and have it replaced with a combi. The chances are that it has had a good innings and needs to go to the back boiler heaven in the sky. Dont forget that there are Back Boiler Removal Grants Available Too to replace them at no cost. Back Boiler Removal Grants Here
See This Excellent Guide On Back Boilers
How Efficient Are Back Boilers?
Back boilers have a much lower energy efficiency rating than their modern combi boiler counterparts. Generally, they are only about 60 -70% energy efficient as compared to the more modern condensing boilers which are over 90% efficient. This means that an old back boiler will be costing you over 25% more in eating costs.
How messy is removing a back boiler?
The back boiler, it’s flue and gas fire – all will be removed unless you want to keep the back boiler fireplace. Removing the gas fireplace and replacing it with an electric fire could cost you more in the short term but less in the long term. So, creating a mess is normal while removing a back boiler.
How much does it cost to service a back boiler?
A service of a boiler, gas fire and hob is likely to be in the £100-£125 range. A boiler service should cost £70-90 (depending on where in the country you are), and that includes cleaning out a magnetic system filter (if you have one).
What Different types of Back boilers Are In Homes?
Gas fire with back boiler behind it A back boiler is usually attached to a copper cylinder full of water which is heated up using some sort of fuel. Usual fuel types will be solid fuel – gas. 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 £700 more per year to run.
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. T
hey are also very messy and take up lots of upkeep. 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.
Are Back Boilers Still Available To Buy?
Yes 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. UK government regulations state that all boiler systems must have a minimum of 86% efficiency, so most models of back boilers are no longer manufactured .
The dangers of back boilers.
If you have had your back boiler decommissioned in the past, it is worth getting it completely removed as there have been some issues in the past. In decommissioned back boilers there will likely be residual moisture inside, which will heat up if you have the fire on in front of it .
This can result in a build-up of internal pressure that can cause an explosion which has caused numerous serious injuries and one fatality. Installers highly recommended you remove any disused back boilers to avoid such tragic outcomes.
How Much To Replace a Back Boiler
You can expect to pay within the region of £3500 – £500 if you choose to replace your back boiler with a combi boiler system. This price usually includes removing the old back boiler and surrounding fireplace and mantle and making good .
The cost of a full removal for an old back boiler from behind the fire will usually vary from home to home due to the nature of work involved.
BACK BOILER REMOVAL ONLY £750
For Homes that already have a full central heating installed and just want the old back boiler removed from behind the fireplace. This price will usually include:
- Decommissioning of back boiler and the attached pipework
- removal of the old back boiler
- full disposal
- capping off of the old pipework.
Making good and any redecoration work will be at extra cost

Useful Resources On Backboilers
Are Replacement back boilers still available?
Back boilers are no longer being manufactured by most companies apart from the Baxi Bermuda BBU HE See Here
When did back boilers cease to be fitted in homes?
In 2005 Building Regulations requirements changed and backboilers were no longer allowed to be fitted in new build houses. This was down to backboilers having very poor efficiency and safety issues.
Can you sell a house with a back boiler?
It is not illegal to sell a house with a back boiler fitted. We do recommend you have it serviced prior to sale and provide a gas safety certificate to the new owner.
Can you rent a house out with a back boiler?
As long as your property is a minimum Energy Performance Certificate rating of E , you are still allowed to rent out homes with a back boiler fitted. If Below E it will be your obligation to upgrade this for your tenant, or before you let out the property to new tenants. A gas Safe Cert will also be required
Are back boilers expensive to run?
Back boilers are a very old form of heating and are usually around to be 70% efficient compared to new boilers which will give you over 90% efficiency. They can be costly to maintain too with spare parts getting harder to find which will make them more expensive.
Should you replace a 20 year old back boiler?
A central heating system using a backboiler behind the fire that is over 20 years old is likely to be made significantly cheaper to run by replacing with a condensing boiler. You will probably save over £200 per year by replacing it. Good idea to see if you are eligible for a grant.
Can a back boiler explode?
If a fire is lit in front of a redundant back boiler that has been left in a sealed condition, it can heat up and the internal pressure can cause the boiler casing to explode. We recommend that when a back boiler is decommissioned , the whole system should be drained and all redundant pipework removed. All properly decommissioned back boilers must be fitted with a safety valve to regulate pressure build up. The back boiler if possible should be removed too.
At the time of writing, there is currently a back boiler removal grant to replace old Baxi Bermuda back boilers for a brand new combi for 100% free. To be eligible you must meet the following requirements:
- Applicants must be homeowners.
- Have a back boiler fitted behind their gas fire.
- Must be receiving a qualifying benefit (Housing Benefit, Income Support etc)
- Please see our Back Boiler Removal Grants Page Here or make an application below.
BACK BOILER CONVERSION TO COMBI COST
BACK BOILER CONVERSION TO COMBI – £3000 -£4000
This is for replacing an old back boiler with a combi boiler.
The new boiler will be put on an outside wall usually in the kitchen or bathroom and new pipe work installed including a gas supply and distribution of hot and cold supplies. This is a large job and can take around 2 days to complete.
Extra Costs
Replacing a back boiler is a big cost . Plan your install and see if there will be extra charges.
- A system boiler will need a hot water cylinder in the airing cupboard and a cold water storage tank in the loft plus further pipework so will be an extra £1000.
- The location of the boiler can affect the cost especially if in an airing cupboard as the flue will need to exit the roof.
- Choose the size of the boiler
- A combi boiler will also save you from the added cost of having a cold water storage tank in the loft as well as a hot water cylinder in the airing cupboard
Making Good After Back Boiler Removal
Removing a back boiler will cause some damage to the existing hearth and fireplace surround. You will need to upgrade the fireplace with a new surround and electric or gas fire or use it for a real fire.
Back Boiler Replacement or Replace With Combi?
We recommend you upgrade to a brand new combi while grants are available.
Backboilers are not the cheapest to run and switching to a combi will save you a large chunk of cash in running costs. You could save around £200 per year by switching to a combi.
