Boiler Replacement UK: Combi Boiler, System & Regular Boiler Swaps

Boiler Replacement UK and New Gas Boilers Like for Like Swaps

Gas Boiler replacement, combi boiler replacement and like for like swaps

boiler replacement and new boiler guide

A new gas boiler replacement is a purchase a homeowner should make only every 10 to 15 years therefore, you must find the right replacement boiler company for a warm and happy home for years to come.

If a combi boiler change is necessary for whatever reason, you’ll be glad to know that new combi boilers are the most replaced boiler in the UK, and you can order yours today with Boiler Central.

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Our Guide Replacement Gas Boilers Summary

In this guide, we will talk about our gas boiler replacement and installation services and what is included when you change a boiler. Here is just a brief overview of what we offer at Boiler Central:

  • Next-day Gas Safe boiler replacement
  • Different ways to pay, including boiler finance
  • Price match guarantee like for like boiler quotes
  • Fantastic customer service & aftercare

Join thousands of happy customers when replacing a gas boiler with installation included from Boiler Central online; if you don’t believe us, check out over 3,500 excellent rated Trust Pilot reviews.

Video: Best Boiler Replacement Guide

This video will guide you all about the best boiler replacements for you.

Gas boilers including combi boiler replacement UK wide for all property types

When considering the wide range of new gas boilers available, the cost varies significantly depending on the model and type of system you require, which depends on the property of the gas boiler that will be installed.

As the best combi boiler replacement company, we love helping our customers and getting a quote for a new boiler online has never been easier.

Homeowners and landlords alike, we look at all your combi replacement gas boiler options at Boiler Central, from a direct swap to a complete back boiler conversion, we can pretty much arrange anything you require.

To help, we’ve produced this replacement boilers guide with everything a homeowner, tenant, landlord or billpayer will need to know and you can use the contents above to find the specific questions you have in mind.

New replacement boilers guide to getting the perfect choice for your home

worcester bosch 8000 lifestyle range

This guide will give you everything you need to know about getting the best new boiler replacement for your property from our experts at Boiler Central, has installed over 15,000 boilers in the UK since we started, so we know a thing or two.

We can’t stress enough how important it is to replace a gas boiler to get the right one for your central heating system to ensure that running costs are low and your replacement boiler can cope with the demands and needs of your home.

Compare replacing boilers for different properties

Learn more below about how we determine the signs of old boilers, types of gas boiler replacements, boiler quotes, boiler installation deals, new hydrogen-ready boilers (20% blend).

Did you know if you install an energy-efficient boiler, it can increase your house price?

Prospective boiler buyers are starting to look at what state the central heating system is in, and even if you are a landlord, prospective tenants are asking the right questions.

It’s almost as important as how big the garden is!

The replacement boiler conundrum – Is it really worth the hassle? We’re obviously going to say yes, but it is backed up by stats from governing bodies like the Energy Saving Trust

Replacing a boiler with a new one and reasons why it is a good idea

With regular servicing, some old boiler models can withstand many years of use, but if you’re reading this, then it’s likely that you will need a replacement boiler, and your boiler may need replacing soon

The repair bills can stack up quickly with an old boiler, especially if you do not have a boiler cover plan. The cost of domestic hot water heating bills will also start to rise as boilers get older and become less energy efficient, hence why buying a new boiler can be an investment.

When should I replace my boiler?

Old broken boiler is beyond economical repair

new boilers from viessmann

If your existing gas boiler is not working and Beyond Economical Repair (BER), it’s usually cheaper to replace a boiler than to get it repaired, and a brand-new A-rated boiler would also save you on your heating bills too.

You can compare replacment boilers online now at Boiler Central and get a fixed price quote online.

Persistent boiler breakdowns

If your boiler is experiencing frequent issues that require multiple repairs or service appointments per year, it may be more cost-effective to buy a replacement.

A leaking boiler could be a sign of a faulty heat exchanger, which can lead to the boiler not functioning properly. In this case, getting a replacement gas boiler would be the best option.

Increase energy efficiency

If your boiler is over ten years old, it is likely to suffer from poor energy efficiency therefore an upgrade is essential.

This usually means expensive gas bills, so a new boiler would be the best option here. An energy-efficient A-rated boiler can save you up to £840 per year on your gas bill.

Adds value to your home

If you are thinking of selling or renting out your property, then having an upgraded boiler fitted can increase the value of your home.

If you decide to sell, your upgraded boiler will often pay for itself because a newer boiler can add value to your home.

If you rent it out, your tenants will appreciate the energy savings on their bills and you may be able to charge more rent.

Leaky boiler

If your boiler leaks, it is likely time to get a new one unless it is under warranty. If leaks are causing expensive call-outs, then a replacement boiler may be the best option for you in the long run.

A boiler that leaks water can sometimes lead to more significant problems.

Moving a system or boiler change

If you are planning to move the system or would like to move your existing boiler to a new location, it’s usually better to get a brand new boiler. It would be less hassle and is usually the best option to upgrade your heating system.

If you’re experiencing any of these major issues, it may be time to replace your boiler.

When should you NOT get a replacement?

If your central heating boiler is under ten years old and has a regular service every year by a Gas Safe registered engineer, then there is a good chance that getting a replacement boiler won’t save you any money at all on your energy bills.

If you are in doubt, speak to an expert or book one of our engineers for a boiler service now, as they can maintain your boiler’s efficiency whilst also advising on whether a replacement is right for you!

A boiler service costs around £100 which is much cheaper than expensive repairs and can help keep your gas bills down too.

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How to get the best replacement boiler for your home

Hot water usage

Deciding on the best type of boiler replacement depends entirely on your home; for example, a small London flat with 1 bedroom would have a different replacement boiler than a 5-bedroom home in Mayfair.

Here, we have listed some main features to look out for when choosing a combi or gas boiler replacement, and the key things to factor into your decision are:

1. Hot water usage:

Large families that use a lot of hot water will find a regular boiler or system boiler more efficient.

Therefore, a home with fewer occupants will benefit from a combi boiler

This will mean that running costs are lower, which will keep your energy bills down.

2. Home size:

Because combi boilers don’t require hot water cylinders, we can install them in a home with less space. See our recommended replacement boiler size chart or use this boiler size calculator to get the best boiler for your home

Size of Home & Hot Water DemandCombi Boiler Output
1–3 bedrooms, 7–10 radiators, 1 bathroom20–29kW
3–4 bedrooms, 11–15 radiators, 1–2 bathrooms30–35kW
4+ bedrooms, 16–20 radiators, 2+ bathrooms36–60kW

3. Solar water heating compatibility:

If you’re using solar to power your hot water, it’s essential to know that many combi boilers are less compatible and inefficient with this heating system. Contact us if you’re unsure.

Read more: Types of Boilers: Which are Best for Your Home?

When replacing regular boilers or system boilers, you should be able to keep the hot water cylinder to go with your boiler installation.

Combi boilers are the most popular in the UK. A combi boiler, also known as a ‘combination boiler’, is a 1-unit system that typically lives in a kitchen cupboard.

A combi boiler is brilliant unless you require a high demand for water at once to multiple taps. In this case, you would be better with a regular boiler.

Arguably, a replacement boiler is an investment. Over a period of time, especailly now with ridiculous gas prices, you could get your money back. And the more they rise the greater this investment becomes.

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Replacing a gas boiler of a different type

When replacing a boiler, it is standard to replace your boiler with another boiler of the same type. For instance, swapping a combi boiler for another combi boiler, or a system boiler for another system boiler.

If you want your replacement boiler to be a different type of boiler, we call that a ‘conversion’. A system-to-combi conversion is a common type of installation, especially for households who want to free up more space in their homes.

New central heating boiler comparison table

Replacement Boiler TypeHome SizeBathrooms & ShowersRadiatorsOther Reasons To Buy
Combi Boilers1–4 BedroomsUp to 2 Bathrooms5–20 RadiatorsCompact & Easy To Install
System Boilers3+ Bedrooms2+ Bathrooms10+ RadiatorsHigh Hot Water Demand
Regular Boilers3+ Bedrooms2+ Bathrooms10+ RadiatorsLow Water Pressure

Choosing a gas boiler replacement company

At Boiler Central, we specialise in replacing gas boilers, and while anyone can purchase a replacement boiler, it is important to have a specialist install it.

We replace thousands of gas boilers throughout the UK annually, and we do not currently offer oil or electric boiler replacements. It’s crucial to choose the right gas boiler for your home, and with Boiler Central, you can quickly find the perfect boiler for your home online.

Below, we provide a range of replacement boiler options and provide more information on the different types of new boilers, and help you find one suitable for your home.

Combi boiler replacement

Find you next new combi boiler replacement from Boiler Central today. Combination boilers, also known as gas combi boilers, are the most popular type of home boiler system in England.

Simply turn on your taps or flick on your handy wireless thermostat and they provide instant hot water and efficient central heating — Luckily, most new combi boilers run at over 90% efficiency.

This ultra efficiency and energy bill reducing ability is due to the condensing technology involved and improvements in parts and energy-efficient components.

Pros and cons of getting a combi boiler

Boiler replacement and new boilers


  • New gas combi boilers don’t require any external components, so they’re sleek and compact.
  • Hot water is available on demand.
  • They are more affordable to install than regular models.
  • A replacement combi boiler is easy to install.


  • More internal moving parts mean there are more potential malfunctions. These issues may be more expensive to fix than with a conventional boiler. 
  • Hot water from a combi boiler system can only support one user at a time. This makes combi boilers less suited to a larger home. 

Get a boiler quote with an instant finance decision online – Click here

Like teachers used to say: if you don’t know, ask. The right replacement boiler is so important, don’t make a mistake.

Why upgrade or replace your combi boiler

There are many reasons why you should get a new combi boiler replacement.

The first is that, according to the Energy Saving Trust, you can save £840 a year on your gas bills if you change from an old G-rated boiler to a brand new A-rated combi.

By getting a new combi boiler, you could pay for your boiler in a matter of years. With ever-increasing energy bills, getting a new combi boiler has never been more vital.

If you need help choosing the best combi boiler replacement for your home, fill in our survey and get a fixed price online today. Get my quote>.

How long does it take to replace a combi boiler?

A simple swap from an old combi boiler to a new combi boiler is straightforward and usually takes 4–6 hours for a Gas Safe engineer to fit.

If you want to replace a system boiler with a combi boiler, this can take longer as there’s extra work to disposing the old water tank.

Read below to learn more about gas boiler replacement and changing a system boiler to a new combi boiler.

System boiler replacement

System boilers are sometimes called ‘closed-vent boilers’ as they work on a closed system with a hot water cylinder.

Viessmann new boiler

These are perfect if you prefer a heat-only boiler but would like fewer external components. System boilers do not require the cold water tank that conventional boilers do.

Like a combi boiler, these models have their external components built into the body of the heating system. 

System boilers contain a hot water cylinder, but the feed and expansion tanks are supplemented with an expansion vessel in the new boiler. This is where the circulation pump and the valves are housed. You don’t usually need to change the hot water tank unless it’s old.

Pros and cons of getting a new system boiler


  • System boilers work well in large homes where heated water is needed for more than one task at a time.
  • They don’t require as much space as a conventional boiler.
  • System boilers are very efficient in areas with low water pressure.


  • They require space for the hot water cylinder.
  • Installation costs are higher than with basic combi boilers.
  • They are less efficient than combi systems, since they lose heat from stored water in the hot water cylinder.
  • It takes time to heat up again after the hot water empties from the cylinder. 

Some like it hot. Some like it really hot, really quickly. System boilers are unrivalled at hot water delivery.

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Regular boiler replacement

Heat-only boilers, sometimes called ‘regular boilers’ or ‘conventional boilers’, provide heating and hot water with the support of a hot water cylinder and cold water storage tank.

new boiler replacement

They’re able to deliver large amounts of hot water at a much faster rate than combi boilers, and can supply multiple taps and showers simultaneously.

The circulation pump and expansion tank are housed as external components. 

These typically feature an on-and-off switch, so you can control your heating with ease: heating the water in the storage tank when you know you’ll use it, and conserving energy when it’s not in use. 

Pros and cons of getting a new conventional boiler


  • Conventional boilers work well with large households.
  • Large amounts of hot water can supply multiple taps at once.
  • Suitable for homes with low water pressure.


  • Replacing a conventional boiler with a combi can be a complicated process.
  • Not as energy-efficient due to the constant heating of the hot water cylinder.
  • Less choice of replacement options.

How much is it to replace a boiler?

Cost of upgrading a boiler

A boiler upgrade is an excellent investment for your UK home. Whether that’s a gas combi boiler, system, or regular boiler, they all have their place in certain home types.

We offer authorised and regulated payment options to ensure you can afford whatever boiler you choose.

Based on the new boiler you’ve chosen and our intake evaluation, new boiler costs will vary.

Can I change the boiler I want to replace?

removing a tank when getting a new boiler

Yes, changing a boiler type to aid energy efficiency or make space in your home is becoming increasingly popular.

Most people choose the new boiler when replacing the same type, but converting from a system boiler to a combi boiler is always an option.

When you decide to convert from one type of boiler to a different one, you rearrange pipework and either remove or add a hot water tank or cylinder.

All these can be quickly completed in 1-2 days by a fully trained and qualified heating engineer.

One thing you will need to remember, though is that this fitting of a completely different unit will come at a cost due to the amount of work involved.

If you have made up your mind or don’t have much choice, you can now find out how much a conversion is in under 20 seconds online with Boiler Central.

Financing the new combi boiler replacement

A combi boiler replacement costs significantly less than regular models because these models are less complex, however, the price of your combi replacement will depend on the labour required to fit in the model of your choice.

New boiler financing options

Some combis are more expensive too, but that doesn’t mean you can’t afford one. Help is at hand with our panel of lenders here at Boiler Central.

Financing options

If you’re overwhelmed by the cost of your new boiler replacement, don’t fret. There are many boiler finance options available to you.

We have different lenders with different acceptance criteria to help you get the boiler you want.

We offer access to a new gas boiler with 0% interest-free financing, interest-bearing credit, and monthly payment options regulated by the Financial Conduct Authority.

Replacement gas boiler warranties

If you are replacing a boiler, you will want to ensure you get the best warranty available. Twelve years is the industry standard on some of the best models.

Boiler Central, however, offers 12 years warranty on boilers that have ten years as standard from a manufacturer.

We use our vetted and trusted Gas Safe engineers to handle all of your boiler replacement needs for safety and peace of mind. With any boiler, you will get a warranty, which can only be valid if it is carried out by a fully trained and registered gas engineer.

Gas Safe logo

In our busier months, some of our old boiler replacements are fitted by our trusted subcontractors.

We assure you that our engineers will perform with the utmost safety and professionalism.

You must also ensure that your boiler is serviced yearly to keep your warranty valid.

The new boiler warranty length is factored into the cost along with your satisfaction and ability to remain stress free at home after a long day of grafting

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Cheap boiler replacement

If you are looking for a cheap combi boiler, you can choose from some excellent options on the market.

New Alpha boiler

It must be said that, in general, you will find that the cheaper boilers are, the shorter the warranty will usually be.

For example, you can pick some budget boilers up for £1,499, but they may have a two or 5-year warranty.

If you spend a little more than these cheap new gas boilers, you can get more extended warranties, from 7 years to 10 years, from manufacturers like Worcester Bosch.

Getting the cheapest replacement boiler is not always the most brilliant idea. You may be better off getting a more expensive boiler with a more extended warranty but finance it over 10 years so it’s paid off in manageable chunks.

Boiler Central offers 1 to 10-year finance, so get a quote here to see your options. You can even see the monthly repayments and ensure that it’s cheap enough when you replace your boiler.

What are the cheapest replacement boilers?

Below we round up some of the cheap new gas boilers that you can get your hands on if these are your desired price:

  • Navien NCB 300 combi boiler
  • Worceter Bosch 1000 combi boiler
  • Vokera EasiHeat 25kW – These gas boilers are great workhorses for 1–3 bedroom homes – Price one up – click here
  • Alpha E-tec boilers – Fantastic replacements from 29kW power
  • Vaillant boilers – They have some cheap boiler options in their range

Many of the above new gas boiler options are cheap, in the region of £1,699 model and retailer dependent – Read more here about cheap replacement combi boilers.

Boiler replacement deals & offers

There are not many deals to be had with boiler replacements, but companies like Boiler Central offer some unbeatable deals, such as up to a 12-year warranty on all Worcester Boilers and Viessmann boilers purchased online.

You also get your boiler controls, such as a free wireless thermostat or you can upgrade to a smart thermostat to help keep energy bills down.

This deal is unheard of in the industry, and we were the pioneers to introduce this fantastic combi boiler replacement deal into the online market.

If you want to spread the cost of a replacement boiler to make small monthly repayments, look no further than our boilers on finance with no deposit.

Here at Boiler Central, you can get interest-free boilers over 2 years, buy now, pay in 12 months or spread the cost over 10 years if required and pay as little as around £10 per month!

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Are boiler replacements the right option?

Having an inefficient boiler can lead to high gas bills and negatively impact the environment. Upgrading your boiler can save you up to £580 per year on energy bills.

It’s best to replace your boiler before the winter months, as most homes have their heating on during this time. If you’re concerned about energy costs, consider investing in a smart thermostat to further reduce gas and electricity usage.

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How easy is getting a new boiler?

It couldn’t be simpler when getting a boiler replacement.

Gone are the days when you have to call British Gas (who are around 3 times as much as us, seriously) who would send out a surveyor to your home.

Well, we say surveyor… They are salespeople disguised as a surveyor.

Now you can order a boiler upgrade from anywhere worldwide if you have an internet connection from your phone, tablet, or desktop computer.

Get a boiler quote with an instant finance decision online – Click here

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Which is the best new boiler?

There are many new boilers to choose from in the UK but here we have ranked them in order which we think are the best then check out our best combi boiler guide for a more in-depth review.

With the best brands like Viessmann, Worcester Bosch, Ideal and more all competing with a wide range of models and outputs then, you can guarantee you can get the perfect boiler for your home online now.

What to do next to get fast gas boiler replacement in 24 hours?

Using Boiler Central’s online quotation system to get the perfect boiler , answer nine simple questions about your home and water usage to find the fuel and boiler that’s efficient for you.

Once we’ve received your information, we’ll act as a credit broker to help you finance your boiler replacement if you require finance.

You can also pay after boiler by card, Paypal, or even buy now and pay in 12 months.

We’ll provide a list of boilers we can install, including a budget replacement boiler right through to mid and top-end boilers, by answering 9 simple questions.

Next, choosing the best new boiler replacement for your home is down to you.

All the recommended units will be suitable, but you need to pick one that’s within your budget, or if there’s a particular brand you like then you can choose them.

How to replace a gas boiler with a different type

If you are looking at how to replace a boiler with a different type, then you can use Boiler Centrals online replacement quote builder and choose to convert to another type.

You then also need to decide if you want to keep your tank.

However, this will not be possible if you want to change a boiler to a combi. If in doubt, contact one of our experts now to replace a gas boiler for you as soon as tomorrow!

After Boiler Central has installed your boiler

When your Gas Safe installation is complete, we will contact the boiler manufacturer to register your warranty.

If you have taken up one of Boiler Central’s offers of a free 2-year extra warranty worth £500, this is automatic, and we will register your details on our system.

Also, at Boiler Central, we love how good our customer service team is, so in the unlikely event that there are installation issues with your new boiler, we are on hand to resolve this for you ASAP.

You can call us any time, and we will also reach out to you throughout the day to ensure that everything is going as you expect!

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  • Next-day installation
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12-year warranty on Worcester Bosch & ViessmannGet a quote now >