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2020 Back Boiler Replacement Cost Guide

Welcome to our 5-minute back boiler replacement cost guide.

We’ll cover everything from what a back boiler is, to your replacement options, as well as the average cost of replacing a back boiler.

Got questions regarding back boiler replacement? Leave a comment at the end, and we’ll get back to you as soon as possible.

Most people with a back boiler are likely to want to upgrade to a combi. And, the most accurate way to get a price, is to use WarmZilla’s installation price calculator. They’re a new kid on the block for boiler installs and currently run a promo (use discount code WZ-200 at checkout for a £200 discount) , so their prices are extremely competitive — the Worcester Greenstar 25i starts at just £1,639).

They have a clickable form, covering important details about your property. From their, they can give you a fixed price on screen in less than 2 minutes.

What Is A Back Boiler?

Back boilers are a heating system that are integrated into fires.

If you have central heating, can’t see a boiler, but have a fireplace; it’s a back boiler fire.

Why Houses Have Back Boilers

Back in the 1960s, back boilers became popular. Like combi boilers today, they were the latest technology.

They were fitted in properties up until around the early 80s. Then regular, system and combis started to take over.

Should You Replace A Back Boiler With A Gas Boiler?

Back boilers are not energy efficient. And, that means you’re losing cash on your utility bills. 

Replacing a back boiler with an up-to-date A-rated boiler will save you cash. Many newer A-rated boilers are over 89% efficient.

If you are having problems with your back boiler, it’s rarely a financially viable option to fix them.

Due to the age of these units, it’s likely other parts will deteriorate within the next few years and you’ll need to replace it anyway.

We’d always advise upgrading to a combi boiler where possible. You can get a fixed price on screen using this form.

Back Boiler Removal Costs

First, you’ll need your back boiler removed. If you already have a central heating system installed and want your back boiler removed, it’s likely to cost around £600-800.

That will include removal of the boiler and capping pipework. More importantly, the back boiler and pipework needs to be decommissioned.

Back Boiler Replacement Costs

Most back boiler replacements are called system upgrades. A system upgrade is converting one central heating system to another.

In this case, that’s converting your back boiler heating system, into an energy efficient boiler.

This could be gas, LPG, electric, or oil. And, the system setup could be regular, a system, or combi.

The Cost Of Replacing A Back Boiler With A Combi

If you’re swapping a back boiler for a combi boiler, expect to pay around £3000+.

That would assume a Worcester 25i boiler was fitted (costing around £1,300 including flue, controls etc).

The Cost Of Replacing A Back Boiler With A Regular, Or System Boiler

The cost of replacing the back boiler fire with a regular or system boiler will be similar to a combi, assuming the same KW boiler is used.

Expect to pay around £3000 for a 30KW regular installation or system boiler, as a replacement for your back boiler.

Replacing A Back Boiler, In A New Location

Back boiler replacement cost doesn’t just consist of a new boiler.

All boilers need a flue, to vent gases from the boiler.

Back boilers flue through the chimney, whereas newer boilers use a horizontal (to go through the side of a wall) or a vertical flue and extensions (to go through your roof).

You’ll need to plan a new location for your boiler. And, most of the time that’s ideal. It can be tucked away, rather than being on show.

If you are looking for your back boiler to be replaced with a combi in a small cupboard (such as in the kitchen), manufacturers design boilers especially for these cases.

A typical example is the Worcester CDI Compact range, and Ideal Logic Plus’s.

Both boiler ranges will fit in a standard kitchen cupboard.

Typically, you should expect to pay an additional £300-600 to move your boiler to a new location during installation. You can double check the cost of different locations (airing cupboard, loft, kitchen and so on) here.

Back Boiler Replacement Costs (Full Central Heating Installation)

There are plenty of properties that would benefit from a full central heating installation. Remember, even if pipework is in place, it’s likely 40-50 years old if it’s being powered by a back boiler.

So, how much does back boiler replacement cost, including all pipework?

That’s not an easy question to answer. The price will vary from property to property.

A typical 3-4 bedroom property with 8-10 radiators, all pipework, and an A-Rated combination boiler, is likely to cost around 5,000.

Take that as a guideline. The difficulty of laying pipework, the size of radiators, the size of the boiler (and type) will all contribute to the cost of a full central heating system.

And, if you need to replace a back boiler with a “system” boiler, you’ll need a cylinder, and additional pipework.

Additional Costs For Regular And System Boilers

Regular and system boilers have additional components to make central heating work. These can include cylinders and hot water tanks.

If these need replacing or upgrading, this will be at an additional cost. For cylinders, we’ve created a cylinder installation cost guide.

How To Get Your Back Boiler Replaced, At A Competitive Price

Without visiting a property, it’s hard to determine the right route to take. Some properties will need a small combi boiler (24kw), whereas others will need a large (40kw+) system boiler.

When having any part of your central heating replaced, it’s important to get more than one quote.

What To Check With Your Engineer When They Come To Quote

Replacing a back boiler is a big investment. As we’ve mentioned, each property is different, so you’ll want to get an advice (most engineers will give this for free as part of their quote).

One of the most cost effective ways to get a back boiler replaced and upgraded for a combi, is to use WarmZilla. Given they’re currently running a promo, boiler installation prices here are lower than most national companies, and even local installers in many cases.

If you do use a local installer, here’s a few things you’ll expect from your engineer (you can find local installers here):

  • Their Gas Safe credentials.
  • Where the flue will be located.
  • Recommended boiler, and it’s warranty.
  • That the quote is a fixed price.
  • The quote includes boiler filter installation (so your system doesn’t gunk up).

What’s Next?

Thanks for reading our back-boiler replacement cost guide.

If you have any questions regarding back boiler replacement, leave a comment below. We’ll get back to you as soon as we can.

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  1. Paying British Gas £35 monthly, to keep our (1982) baxi back boiler system functional. Although, following the annual service they say the boiler should be replaced.
    Cost of removing and installation of a modern system, leaves me perplexed.
    Uncertainty leaves me resigned to costly heating costs, instead of an expensive loan.

    1. Hey Sam.

      There’s a guide here, although it’s rough prices as it really depends on your system/property: https://heatingforce.co.uk/blog/boiler-installation-costs/

      Also a guide on boiler finance: https://heatingforce.co.uk/blog/boilers-on-finance/

      There are 0% APR option available. Just make sure you get a few quotes (from local installers that don’t offer finance too) for a direct comparison on price.

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