Back Boiler Replacement Costs: The Real Cost of an Upgrade

Ready to upgrade your central heating but don’t know where to start? 

Our detailed guide to back boilers covers everything you need to know before getting a replacement, including:

• What a back boiler is
• Why you should upgrade your central heating system
• What you should expect when it comes to back boiler replacement costs

In Summary: Understanding Back Boilers and Their Replacement Cost

Back boilers are an old way of powering your central heating system developed back in the 60s, and were popular up until the 80s.

Since 2005, the installation of back boilers has been prohibited. This isn’t just due to safety concerns, but also due to their incredible lack of efficiency. A typical back boiler will run at around 70% efficiency, in comparison to a new A-rated boiler that will run in excess of 90% efficiency. 

If you have a detached house using a G-rated back boiler that then has an upgrade to an A-rated combi boiler, you could be looking at £330 per annum (£27.50 per month) in energy savings. Essentially, the energy savings alone could pay for your new boiler.

The cost of removing a back boiler and then upgrading to a combi, conventional or system boiler setup isn’t a quick and easy job. And that’s going to mean costs are much higher than a straight boiler swap. 

Typical costs involved with replacing a back boiler with an up to date A-rated unit are likely to sit in the £3,500-£4,500 for the average property. Costs can be higher depending on variables such as: the type of system you need installed, how much new pipework is needed and the type of radiator valves you choose.

Want to see exactly what a back boiler conversion would cost for your property? Use our quick and easy 2-minute clickable boiler installation quote form here.

What is a Back Boiler?

Back boilers were popular back in the 60s, and use heat from a fireplace to heat hot water in your central heating system. 

The system works in a similar way to modern central heating systems, but in many cases the fuel source is burnt in an open environment (e.g. an open fire), leading to a huge loss of efficiency. A lot of back boilers sit in an old chimney breast meaning the majority of heat generated is able to escape.

A combination of low efficiency ratings and various safety concerns meant that in 2005, installation of new back boilers was prohibited in the UK.

Why Should I Upgrade My Back Boiler to a Combi?

There are two main reasons you’ll want to convert your current central heating system from a back boiler to a combi, system or conventional boiler setup:

• Efficiency 
• Safety

Efficiency

Given many of the original back boilers were open fires, their efficiency ratings are incredibly low. An A-rated gas boiler these days will run at around 90% efficiency or higher. Compare that to a back boiler that runs at around 70% efficiency with a lot of heat / energy escaping via the chimney breast.

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(Source: Energy Saving Trust)

As you can see from the image above, upgrading to an A-rated boiler with a modern programmer, thermostat and thermostatic radiators valves (TRVs), could see a saving of around £330 per annum.

With a range of finance packages available, the monthly energy savings of upgrading from a back boiler to a modern unit could almost pay for itself.

Our 2-minute clickable boiler form here will take into account all details relevant to your property and current heating system, giving you a fixed price on screen for your upgrade. 

Safety 

Back boilers are not physically “banned” in the UK, but building regulations mean that they can no longer be installed. 

Any unit burning fossil fuels poses a range of health risks. However, modern boilers have a range of fail safes incorporated into their design and are much more enclosed than most back boiler setups; there’s less chance of carbon monoxide escaping.

Modern units will automatically lock-out when an issue arises, display a fault code and won’t be able to be reset until the problem is fixed. 

Like most technology in the 60-80s, back boilers are outdated and their fail safes are not up to current safety standards in the UK. So aside from the obvious energy savings mentioned above, a big reason to change from an old back boiler to a new boiler is simply due to safety concerns.

Back Boiler Replacement Costs

Below we’ve given some cost estimations related to replacing a back boiler, split into:

• The total cost of converting a back boiler to a combi, system or conventional central heating setup
• The cost of decommissioning as a stand alone service
• How much you should expect to pay for the best combi boilers

Our clickable new boiler form can give you a fixed price on screen for your back boiler replacement. 

Total Replacement Cost

No one boiler installation is the same, so costs can vary massively depending on a huge range of variables. Each property will have differences in:

• Heating demand - More radiators generally means more heating demand. The more heating demand, the bigger the boiler required to keep them hot
• Length and current state of the heating run - In some cases, pipework might need to be upgraded or totally replaced. The more pipework that needs installing or upgrading, the higher the cost associated with the installation
• Rad valves and thermostats - If you have a central heating system that’s got a fairly new thermostat or rad valves, these may be able to be reused and that’s going to reduce the overall cost. 

A normal combi boiler swap is likely to sit in the £2,250-£3,000 range; this is generally the cheapest and easiest boiler installation job. 

Additional work involved with a back boiler conversion includes: upgrading pipework, decommissioning and removing the old back boiler, new thermostatic radiator valves and new heating controls. 

All things considered expect your back boiler replacement to be in the region of £3,500-£4,500 in an average property. You can get an exact price on-screen for your upgrade here. 

Decommissioning a Back Boiler

Not all back boilers can be safely decommissioned. Decommissioning would involve leaving parts of the old heating system in place and this isn’t always possible or safe.

We’d suggest completely removing the old back boiler heating system where possible and upgrading to a new combi, system or conventional boiler using its own (new) pipework. 

Not only is this safer, removing the old system is going to free up some space in your property. 

How Much Are The Best Combi Boilers?

Combi boilers are the most popular type of boiler for the average UK home. If you have reasonable hot water and heating demand, they’ll be perfect. If not, you may need a system or conventional boiler (and need extra space to house the hot water cylinder / cold water storage tank). 

If you check out our guide to new boiler costs here, you’ll see the average price of a combi from a leading boiler brand sits around £1,000. We’d be looking at combi boilers such as the Alpa E-Tec, Ideal Logic Plus, Vaillant EcoTec, Viessmann Vitodens and Worcester Bosch Life; all coming with a 10-year warranty or higher.

Add the likes of heating controls, radiator valves, parts (pipework, fittings etc) and your overall cost is £2,250-£3,000. As we’ve mentioned above, there’s extra work involved in removing a back boiler system, meaning costs are generally going to be closer to £3,500-£4,500.

You can see exactly what the price is likely to be using our clickable boiler installation quote form here. It takes less than 2-minutes, and you’ll have a fixed price on-screen (no need to speak to sales people).