Category - Boilers
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Will Scholfield, Engineer

30 Jun : Updated 18 Apr ● 6 min read

Are back boilers now illegal?

Back boilers reached their height of popularity during the 70s and 80s and are still fuelling many of the UK's central heating systems. Sitting right behind your fireplace, a boiler that fits perfectly, tucked away without the need for any extra space in the house.

The UK government made installing new back boilers illegal in 2005 when building regulations made it a requirement to install only high-efficiency condensing boilers. Although many have now been replaced by wall-hung condensing boilers, there are still a large number of back boilers in use across the UK.

The following article will provide you with all you need to know about back boilers, how much a back boiler replacement costs, and what alternatives are out there that won’t break the bank.

What are back boilers?

Back boilers came into fashion around the 1960s as an easy and out-of-sight option behind a fireplace, chimney or stove, as a way of providing heat and hot water to homes across the UK. 

How do back boilers work?

Back boilers were built to save space for a heat source, and they are designed to fit in the fire opening behind a fireplace and use the same chimney to disperse the gases.

The back boiler features a cold water inlet source located at the bottom. The heat exchanger then heats this cold water and sends it to the output using an electrical pump. To make sure pressure doesn’t build up, hot water is kept in a hot water cylinder that features an overflow vent. 

Why is it illegal to install a back boiler?

As combi boilers and gas or oil boilers took over the market after the 1980s, the parts for repairing or replacing a back boiler became less and less available.

However, the main drawback is their inefficiency. While most modern boilers have the ability to provide up to 98% efficiency, all new gas boilers have a minimum performance standard of 92% (ErP). However, a back boiler can provide maximum efficiency of 80%, making them incapable of meeting today's efficiency requirements. 

This low-efficiency rating will greatly increase the energy consumption within your home, as well as affect your carbon footprint. 

Risks associated with back boilers 

There are also some risks associated with back boilers. 

Back boilers have a life expectancy of 20-30 years. However, as the boiler ages, the risks associated with back boilers only increase. 

  • When a back boiler is reused after being out of use for an extended period, residual water heats up and creates pressure which can be very dangerous.
  • As the fireplace is close to the boiler, the heat and gas trapped in the fireplace without the use of a flue pipe can cause the boiler to explode.
  • Poor ventilation and a lack of access to fresh air can result in toxic fumes building up in the home.

Whilst these occurrences are rare, if you do observe your back boiler overheating or suspect any other problems, call a heating engineer immediately. 

Other cons associated with back boilers

There are also several other problems associated with back boilers:

  • They aren’t able to provide instant hot water
  • The ventilation system can be a source of noise and draughts
  • Back boilers depend on chimneys which can be problematic if you want to do building work
  • Back boiler parts are limited, so replacing damaged parts is difficult
  • Back boilers constantly expand and contract, which can cause structural damage to your home

The cost of removing a back boiler

If you’ve decided to upgrade your heating system, you’ll likely want to know how much it will cost. 

Firstly, you’ll have two options:

  • Remove your back boiler
  • Or decommission your back boiler (disconnect from the gas)

If you choose to remove your back boiler entirely, you should expect to pay around £3,500 to £4,500 for the whole process, including having your new boiler installed. 

However, decommissioning your back boiler is the cheaper option (and will save your house from being turned upside down), and you can expect to pay between £3,000 and £4,000 for the whole process and new installation. 

Back boiler alternatives

Many options are available if you’re looking at replacing your back boiler. However, you might not know what’s best for you and your home. 

Read on to find an alternative to your back boiler:

Combi boiler

This might be the best option if you live in a smaller property that doesn’t have 2 or 3 bathrooms being used simultaneously. 

Probably one of the most popular systems currently available in the UK, an A-rated combi boiler heats your water and radiators from the same unit and therefore doesn't require a lot of space or extra parts.

Combi boilers can run on gas, oil, LPG or electricity, which makes them very versatile and one of the UK's favourites due to the following benefits:

  • Cheapest option and very energy efficient
  • Small size
  • Hot water on demand

You can expect to pay anywhere from £1,500, all the way up to £3,500 for a new combi boiler - including installation. 

For a closer look into combi boilers, take a look at our guide - Combi Boiler Pros & Cons: A Simple Guide

System boiler

If you have a home with several bathrooms and thus a higher water consumption, you might opt for a system boiler.

They require a hot water cylinder to function, so they take up more space than a combi boiler. However, this means that a large amount of hot water can be stored for hours at a time. 

A system boiler comes with several other benefits:

  • Economical and efficient
  • It can be combined with solar energy
  • Easy installation
  • Quick to heat your home

Prices for a system boiler can be anything from £2,000 - £2,500.

For a closer look at system boilers, take a look at our guide - What Is A System Boiler?

Standard boiler

These boilers can be a great way to produce heat and hot water at high volumes. Standard boilers are a great choice for larger homes with multiple bathrooms. 

A standard boiler uses hot and cold water storage tanks, usually installed in your loft, to supply water to the mains. 

Whilst standard boilers aren’t as common as they used to be, you can still purchase these boilers at the cost of £2,000 to £3,000. 

For more information, discover our guide - What Is A Standard Boiler?

Biomass boilers

These boilers offer an alternative to gas, LPG or electricity by using pellets that can be sustainably sourced. 

The cost of biomass boilers can vary depending on the size, make and model, but you can generally expect to pay between £7,000 and £15,000. 

Replace your back boiler with BOXT

There are many good reasons you should replace your back boiler sooner than later: 

  • Save money
  • Be more energy-efficient
  • Be more environmentally friendly
  • Eliminate the risks associated with back boilers

Which boiler replacement option you end up going for depends on your requirements. Consider factors such as water demand for your home and how vital instant hot water is to you and your family. Whether your house has one or more bathrooms plays a significant role, as well as whether you will have enough space to house a water storage tank.

Thanks to the plethora of options for a new boiler at BOXT, you have access to boilers that will be fitted precisely to your needs. 

Or why not try BOXT Life - from only £35 per month, you’ll receive a brand new boiler with installation, unlimited boiler repairs, replacement and servicing, and a Google Nest thermostat - all with no deposit needed. 

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