Back Boiler Replacement – The Complete Guide

Back boilers have made their mark, but gone is their time of being in the spotlight. Not only are they sparsely energy efficient heating systems, but they also invite threats rising from their old age.

It may not be surprising, but finding a back boiler in home is not as rare as you may think. So, if you’re navigating through the process of replacing a back boiler, you are not alone! Read on for a back boiler replacement guide and reclaim a space for your home in the modern age.

Why Should You Replace Your Back Boiler?

If you take a trip down history, you’ll know that a back boiler is set inside the chimney breast, right beyond a gas fire. This boiler system emerged in the 1960s, gaining popularity in the 70s and 80s. The typical homeowner replaced open coal fires with a back boiler and gas fire. With the development of modern boilers and other heating system options, back boilers have fallen obsolete.

There are three significant reasons why you need to replace your old back boiler.


Even the most top-notch back boilers have a life of only twenty to thirty years. It is natural that even the “most recent” back boilers dating back to the 1980s are at the end of their course.

In addition to this, you cannot get spare parts as a replacement for old ones. It means that most of the servicing that back boilers undergo is bound to be sub-par, amplifying the risks associated with gas.

If you do not use your old back boiler, leaving it in place is not the best option. The valves will corrode and age, opening up paths for gas leaks.

Energy Efficiency

Even if a back boiler system functions optimally, the most efficiency you can expect from the heating system is 70%. In contrast, a modern combi boiler can get you an efficiency rate of at least 92%. New boilers need to reach this minimum efficiency rate as per the laws today. You can save considerably on your heating bills and energy bills with replacement options.

Appearance and Aesthetics

A gas fire dating back to the 60s and 70s is not the prettiest sight. It can bring down the appeal of any decor. A boiler replacement could fetch you several new opportunities, like installing an electric fire or combi system. These work excellently in terms of heating while being cost effective and aesthetically pleasing.

What Does Back Boiler Replacement Involve?

When you need a new heating system to take up the mantle of your old regular boiler, it is vital to be familiar with the nuances.

The Type Of Boiler You Need

In deciding what sort of boiler will better serve your needs, there are a few considerations involved. The sort of boiler you require depends on your house’s size and the water pressure. Here are the three most common type of boilers:

System Boilers

In homes that have a high demand for hot water, a system boiler will typically be ideal. They work by boiling water from the boiler in a separate storage tank. This differs from a boiler with a combi system since the latter heats water straight from the supply of the mains. It does not retain hot water, meaning you can fail to run two baths together.

Combi Boilers

The name “combi boiler” stems from its ability to both, catalyse central heating in your home and supply you with hot water. Combi boilers are directly attached to the flow of mains water flowing into your house, directly heating this water, eliminating the need for a separate water tank.

A combi boiler is the best option to replace a back boiler and you may also consider the storage combi boilers.

Regular Boilers

A regular boiler contains both a holding tank for hot and cold water. Naturally, the boiler itself and an extension cistern situated alongside the cold water tank are involved. It takes up quite a bit of room as well. It is typically better to turn to a boiler with a combi system to clear these tanks since they aren’t the most energy efficient alternative to back boiler removal.

How Is An Old Back Boiler Replaced?

Typically, there are two main ways of replacing a back boiler.

Professionals and heating engineers will remove the back boiler in most instances, and cap off the supply of gas. You will be free to open up the chimney again and reclaim the room behind the flames. You can use this space for another heating system like a new combi boiler.

If you can remove the appliance, that’s even safer. You don’t want it to live behind the fire, rusting away!

It is best to replace the boiler or isolate it from all lines of supply in case removal creates a risk of structural damage. It becomes a possibility if a fireplace has been created around the boiler or if it is bricked in.

While this is not the best option, it will spare you from the pain of having to address a messy situation arising from the upheaval of a fireplace.

The hot water cylinder, normally placed in an airing cupboard, is another aspect to consider when replacing a back boiler. A back boiler functions like a system boiler. Back boilers heat water and store it in a tank before you need it. It is unlike a modern combi boiler, which heats water as and when you require.

You can opt to repair the storage tank at the same time and also reclaim the airing cupboard while replacing a back boiler. There is certainly some upheaval with the removal of all the pipework and tanks from your previous setup. However, there is no longer any need for it if you turn towards combi boilers. 

If you have high heating requirements, you can opt to convert from an arrangement of back boiler heating to a system boiler. In such cases, heating engineers will not generally remove the water tanks.

How Much Time Does Back Boiler Replacement Take?

Depending on what the job entails, a rear boiler replacement will take anywhere from two to three days. It is hard to tell without pulling out the gas fire and looking at the scope of the boiler replacement.

The most challenging construction task is to replace an old boiler for a combi. It needs the fire to be extinguished and then the back boiler removed. A redirection of the pipework to the new location follows, with a flue for the new boiler being installed. In the end, tanks and pipework that are no longer needed are withdrawn.

How Much Does It Cost To Replace A Back Boiler?

Back boiler replacement costs will depending on the professionals you choose. Prices often start at £2000 or $2820 to £2500 or $3525. These can go up to £3000 or $4230, possibly even £5000 or $7000.

Back boiler removal quotes or back boiler replacement quotes differ from company to company. Some companies may offer a fixed price. Others may determine it according to the time and effort it takes to replace your back boiler.

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Last Updated on July 4, 2021

Frequently Asked Questions

Are Back Boilers Now Illegal?

Old back boilers using gas fires as their central heating system are close to being illegal. Most back boilers are no longer in line with Building Regulations, thereby calling for boiler replacement. You need to know the government regulations of your state and area when considering replacing your back boiler.

It will be best to get a new boiler such as a combi boiler. Boilers today with more modern technology minimise energy costs as opposed to a low-rated boiler.

Can You Still Get Gas Back Boilers?

Presently, there are new regulations and standards of condensing efficiency. You cannot get new back boilers- back boilers no longer reach minimum efficiency. However, it is possible to fix it if you can locate someone specialised enough to undertake it.


Author: Indra Gupta

Indra is an in-house writer with a love of Newcastle United and all things sustainable.

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