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Boiler Replacement & New Boiler Options 2021

You don't want to buy a new boiler, nobody does. But, when you need to, you'll want to get it right. This is the ultimate guide to new boiler replacement costs.

The boiler is a key part of any modern home, supplying hot water to your outlets and your home’s central heating system.

If you have a broken boiler, you'll start to smell and your house will be cold.

Traditionally, shopping for a new boiler replacement has been complicated, expensive and exhausting. But, we fixed that, by taking the entire process online.

In this boiler replacement installation guide, we summarise the most important factors any savvy boiler buyer should know.

New boiler replacement costs - how much? 

New Boiler Replacement Cost

This question is perhaps the first one that comes to the mind of anyone thinking about a new gas boiler replacement installation.

Look after the pounds, and the boilers take care of themselves

The reality is that no new boiler is pocket change.

But, for a modern, efficient boiler that is going to be supplying your home with hot water, comfort and Pantene Pro-V cleansed locks for years to come, it’s well worth the investment. 

Boiler replacement costs can vary a lot and this depends on a variety of factors, which can be summarised as follows: 

  • The type of boiler you have installed e.g. combi or system
  • The model you choose e.g. mid-range vs. premium
  • If you want to move your boiler to a different location
  • If you want to convert from one boiler type to another
  • Any extras you purchase e.g. smart thermostats, filters etc

For example, a straightforward combi swap (replacing your current combi with another) is going to be cheaper than converting from a system to a combi boiler.

Convert Regular Boiler to Combi Boiler

This is because these installations are more complex, requiring more time, more labour and typically more materials. More everything.

It also depends on the model of boiler you choose, we offer more value-orientated brands such as Alpha, as well as premium, award-winning boiler brands such as Worcester Bosch and Viessmann

The good news is that we offer multiple ways to pay for your replacement boiler, including cash and pay monthly boilers on finance

Read our more in-depth complete guide on new boiler costs. 

Boiler replacement factors to consider 

Factors To Consider During New Boiler Replacement

Since a new boiler installation is by no means a cheap process, it’s important to consider some key factors before making your decision. These include: 

What size boiler do you need? (kW output)

When considering boiler size, it typically refers to the boiler’s power output and not the dimensions of the boiler.

Boiler KilowattA boilers power is measured in kilowatts (kW), so put simply, the greater the kW, the greater the capacity of the boiler to meet your properties hot water and heating requirements.

Typically, boiler manufacturers will offer their boiler’s in a range of different sizes. Your boiler installer (or, our online process) will determine what size you need from the number of radiators in your house. 

For instance, if you live in a small bungalow, then a small combi boiler is probably going to be recommended.

Curious to know which boiler brand performed worst? Find out in our report of the worst boilers


However, if you live in a large, lavish home with many rooms, then a large-sized boiler will be required to meet the heating demands.  

Here are some examples of recommended boiler kW outputs based on your home’s estimated demands: 

  Minimum kW Size  
What size boiler for... 1 Bath/Shower  2 Baths/Showers  
2 Bedroom House 26kW 29kW
3 Bedroom House 29kW 35kW
4 Bedroom House 29kW 35kW
5 Bedroom House 35kW 35kW

Location of the new boiler 

Where do you want your replacement boiler to be installed? It usually makes financial sense to install in the same location as your old boiler as it makes the job more straightforward. 

Relocate Boiler Replacement Cost

However, if you want to move your boiler to a different location, that’s also possible, but you should be prepared to pay more.

Moving your boiler requires more labour and materials e.g. a new flue installed and new pipework re-routing through your home.

It can also make one hell of a mess.

Learn all about combi boilers in our what is a combi boiler guide. 

Energy efficiency 

Securing one of most energy-efficient boilers will ensure you help reduce your carbon footprint, save money on your heating bills and keep you feeling all warm and fuzzy on the inside.

Energy Saving Trust Boiler

All the boilers offered by us at Heatable are modern A-rated boilers, which can be purchased with a smart thermostat, such as Nest to ensure you reduce energy wastage even more. 

In fact, according to the Energy Saving Trust: 

If you replace your old boiler with an A-rated boiler and set of heating controls (you can even operate it remotely via an app on your phone) you could save about £340 and 1,500kg of carbon monoxide a year

Installation Time 

It’s important to consider how long your replacement boiler installation may take, as some are more complicated than others.

A regular combi swap i.e. replacing your old combi boiler with a new combi boiler in the same location takes on average around a day.

However, if you are converting to a new condensing boiler type e.g. from a combi to a system boiler, it'll probably take a couple of days. 

If you live in an average-sized home, see our guide on choosing the best boiler for a 3 bedroom house

When to replace a boiler? 

Right Time To Buy Boiler Replacement

On average, boilers last around 10 years (that's a decade, to you and me), so if your boiler is getting on a bit, it’s a good indication that it might need to be replaced.

In addition to that, there are a variety of other reasons you may want to consider replacing your boiler, these include: 

  • Old, inefficient Boiler
    10+ year old boilers are G-rated and only have an efficiency rating of around 70%. This means for every £1 spent, 30p is being totally wasted. Modern boilers (like the one's Heatable install), are 90%+ efficient.
  • Beyond Economical Repair (BER)
    Often a broken boiler can be incredibly expensive to repair e.g. if components such as a PCB or heat exchanger need to be replaced or repaired, then it may be more cost-effective to get your boiler replaced. 
  • Moving your boiler
    If you are unhappy with your boilers current location, then it may make sense to get a new boiler installed in the new location since it will be covered with a brand new warranty.
  • Current boiler doesn’t meet hot water demands
    If you are finding your boiler is failing to meet your hot water and heating requirements, it may be time to replace your boiler with a model with a higher power output. 

Having issues with your combi boiler? Read our boiler problems and solutions for quick troubleshooting guidance. 

Types of gas boiler replacements

Types Of Boiler Replacements

If you are on the hunt for a new boiler, there are three major types to choose from, these include the following: 

Combi boilers: 

  • The compact design makes them ideal for properties with limited space.
  • Do not need a hot water storage cylinder.
  • Do not need a cold-water tank.
  • Typically, not suitable for larger properties with multiple bathrooms/or a high hot water demand.
  • It may not be suitable for areas that suffer from low mains water pressure.

Regular (heat only) boilers: 

  • Good choice for properties with multiple bathrooms and high hot water demands.
  • Ideal for areas that suffer from low water pressure.
  • Good choice for those with older/traditional heating systems that cannot tolerate high pressure.
  • Since they require a cistern tank, they demand more space and limit gas boiler replacement options.
  • A cistern in the attic is prone to freezing during winter and if it leaks can be problematic.

System boilers: 

Recommended for properties with multiple bathrooms/hot water outlets. 

  • Does not require a cistern tank in the loft. 
  • Internal components make installation easier.  
  • It may not be suitable for areas that suffer from low water pressure. 
  • It may not be suitable for older central heating systems that cannot tolerate high water pressures. 
  • If you are swapping from a combi, you need to consider where you will store the hot water tank.

Learn more about the different types of boilers

Which boiler brands can you choose? 

Which Boiler Replacement Brands

At Heatable, we offer different types of boilers from a range of popular boiler brands, all of which are highly-efficient and award winning or those with an incredible reputation. The boiler brands we offer include the following: 

Worcester Bosch Boilers

Worcester Bosch Boilers

Holding a royal warrant, Worcester Bosch is a household name when it comes to boilers. Several of their new combi boilers have been awarded a Which? Best Buy Award for 10 consecutive years.

Combine that with their excellent guarantee offer, customer service, and easily sourced parts and you have the best boiler brand in the UK.

Read more about Worcester Bosch boilers

Viessmann Boilers 

Viesmann Boilers

Dominating the European boiler market, Viessmann has a 5-star reputation thanks to their superb German engineering and simple, crisp designs. 


Viessmann boilers have won plenty of awards in the past and have a reputation for being technically superb. 

Read more about Viessmann boilers

Alpha Boilers

Alpha Boiler Finance

Alpha boilers are a budget-option brand that has been increasing its market share in the UK wide boiler market over the last few years. They are a fantastic option for the buyer who is looking for a reliable and affordable heating solution with a whopping warranty (10 years exclusive to Heatable).

Read more about Alpha boilers

New boiler replacement finance options  

Pay Monthly Boiler Replacements

If you are unable to purchase your boiler replacement outright, you may be able to take advance of boiler financing options.

If you meet the lender's eligibility criteria, you can potentially pay for your boiler in monthly instalments over 3, 5, 7 or 10 years. 

Pay monthly boiler replacement finance summary: 

  • No deposit required (up to 50% optional)
  • Make overpayments with no penalty
  • Spread the cost over 3, 5, 7 or 10 years
  • Interest rates from 9.9% APR

Pay monthly financing plan examples (with our most popular boilers):

Worcester Bosch Greenstar i Boiler Payment Plans:

Fixed prices from £1,780 (get your quote online)

APR Deposit Loan Amount Term Monthly Payment Interest Total Payable  
9.9% £0 (0%) £1,780 10 Years £22.98 £977.36 £2,757.36
9.9% £780 (Max) £1,000 10 Years £12.91 £549.09 £2,329.08
9.9% £0 (0%) £1,780

3 Years




9.9% £780 (Max) £1,000 3 Years £32.01 £152.39 £1,932.39

Alpha E-Tec Boiler Payment Plans:

Fixed prices from £1,595 (get your quote online)

APR Deposit Loan Amount Term Monthly Payment Interest Total Payable  
9.9% £0 (0%) £1,595 10 Years £20.59 £875.78 £2,470.78
9.9% £595 (Max) £1,000 10 Years £12.91 £549.09 £2,144.08
9.9% £0 (0%) £1,595

3 Years




9.9% £595 (Max) £1,000 3 Years £32.01 £152.39 £1,747.39

*finance examples to be used for illustrative purposes only. Get a finance quote online for final figures.

Read more about boilers on finance in our comprehensive guide. 

Get a new boiler replacement quote today 

Use our new boiler quote tool and we could be fitting your new boiler tomorrow.

Our tool provides you with a fixed price quote for your specific needs, taking into account your property type, hot water demands and budget to provide you with a boiler installation cost that is accurate. It will provide you with a range of recommended boiler models from the brands we work with. 

At Heatable, we believe it’s important to secure a new boiler that offers the following combination: 

  • A long warranty (10 years)
  • A Which? Best Buy (or another industry award winner)
  • High TrustPilot ratings or reviews for customer service

That is why our new boiler deals meet these criteria. 

Use this clickable form to get a fixed price on the screen instantly.

More advice

New boiler deals

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Get a fixed price on a Which? Best Buy in minutes

Heatable is registered in England and Wales No. 08804726 (VAT No. GB205805920 ). Trading address is 1 Station Road, Great Sankey, Warrington, Cheshire, WA5 1RH. Heatable acts as a credit broker (not as a lender) and offers credit products through a panel of lenders. Heatable is authorised and regulated by the Financial Conduct Authority (reference no. 805259).

[1] Price based on a like for like combi swap in a 2 bed, 1 bathroom terraced home with a standard flue

[*] Installation dates are subject to installer availability

[ยน] only available on combi boiler installations

Financial Support: If you are in receipt of certain benefits, you may be entitled to claim a free boiler grant.