Category - Boilers
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Will Scholfield, Engineer

31 Jan : Updated 8 Nov ● 12 min read

How long does it take to fit a new boiler?

Before investing in a new boiler, many ask the question, ‘how long does it take to fit?’

As there will be a minor disruption to your home life when the fit is taking place, this is a pivotal question to ask and one that’s often wondered by those about to purchase a new boiler. 

After all, you don’t want to be left without hot water or a central heating system unexpectedly, and if you know how long it’s going to take, you can prepare.

However, there isn’t a straightforward answer to this question, as timings for boiler installations depend on various factors, including:

  • Type of system/boiler you currently have 
  • Type of system/boiler you want installing
  • The type of fuel being used
  • Whether the boiler needs relocating
  • The type and size of boiler you are installing

As an average estimate, however, a new boiler installation or boiler replacement should take anything from six hours to four days to put in place. 

You can also read our in-depth guide on how much does a new boiler cost.

Keep reading to learn more and to figure out how long it could take to have a boiler fitted in your own home, based on your specific circumstances.

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How long does it take to install a new boiler?

There are many factors to consider when it comes to answering the question ‘how long does it take to install a new boiler?’

Below we have gone into more detail to help you understand the process.

A straightforward boiler swap

The easiest and speediest boiler installation involves switching an old boiler for a new boiler of the same type in the same place in your home. 

For example, replacing an old combi boiler with a new combi boiler.

The usual reason for this switch is that the existing boiler has broken down and is not worth repairing. To put it simply, it’s more cost-effective to replace than repair in some cases, usually when a boiler is getting to the end of its expected life, typically somewhere in the region of 10 years. 

In this case, the replacement boiler will sit in the same place, and as such, the heating system, water and gas pipes will already be in place. On top of this, they will boast the correct specifications for the new boiler set-up. There may be minor alterations of pipework and potentially gas upgrades to do, but often these are all achievable and within a normal scope of work for a straight swap. 

This tends to take a specialist engineer around 6-8 hours to install, assuming that no unforeseen issues crop up, although it makes sense to allow a full day. 

A boiler relocation

If you are also looking to relocate your boiler, this can add half a day to the time it takes to swap out the boiler for a new one. This means that you should expect it to take at least a day and a half to replace and relocate a boiler.

However, this does depend on the property type and size, and the distance between the existing system and where you want your new boiler to be installed. 

Your existing system will already have a pipe directly connecting it to your gas supply, so relocating a boiler involves moving this pipework too. 

This may involve some structural work, such as putting holes in brick walls or lifting floors to navigate the pipes through.

Assuming the old boiler needs to be moved, dismantled or removed, this will also add to the length of time the process takes to complete.

Take a look at our guide to everything you need to know about moving a boiler to learn more.

Installing a brand new boiler

If you don’t have a boiler in place, this may be because you’ve just moved into a new home that doesn’t have central heating or are in charge of building a self-build. 

The time to install the boiler will usually take between one and two days to complete the work.

The time saved by not removing an old boiler will be used to craft new connections to your gas and water mains inlets.

One point to note is that if there isn’t an existing boiler in place, there usually won’t be a central heating system in place either. 

If you’re planning on installing both a new boiler and a new heating system, the time this job takes to complete will rise dramatically.

As an estimate, a brand new set-up with all the works, will likely take between one and two weeks to complete as it will mean lifting flooring, carpets and floorboards and putting down pipework and radiators in place.

The good news? All of this can be carried out at the same time as the boiler installation. However, this may depend on how you choose to do the works on the property; you may need first and second fixes when installing an entirely new heating system and boiler due to other renovation works. 

Changing the type of boiler

All in all, there are a total of three types of boiler to choose from when having a new boiler installed; these include a combi boiler, system boiler and standard (conventional) boiler

All of the available types have different electrical, plumbing and gas requirements, which means if you’re swapping from one to the other, this is the equivalent of installing a brand new boiler as well as removing the old one. 

Changing the type of boiler is, of course, a more complex process than a straight switch, and this will undoubtedly add time.

For example, if you’re looking to convert from a system boiler to a combi boiler, this is going to take longer than a like-for-like swap. The engineer will be required to remove the system boiler water tank and install some extra pipework to your new combi boiler. This can involve lifting floorboards, drilling holes and maybe even running pipes externally, so it can take around 2 days to complete. 

Changing both the type and position of your boiler

In regards to time, the most challenging job is to change both the position and the type of your boiler. This type of job can take 3-4 days or more to complete, as it is a combination of several jobs in one.

On top of new pipework, cylinders and tanks (and often their removal), you may also require new brackets, and in certain cases, you will have to drill holes in walls to re-route gas, water and electric supplies. One of the more challenging parts of installations when moving boilers and upgrading systems can be re-routing the boiler flue, making sure the route and termination of the flue is suitable.

Changing fuel type

If you’re not opting for a brand new boiler and are instead switching the fuel type, it is important to know that this will entail extra electrical and plumbing work, usually equating to an installation time of 2-3 days.

It is relatively rare that you would swap fuel type, however, it is becoming more popular due to people changing from fossil fuels to renewable heating solutions, for example changing from gas boiler to electric boiler. Although these types of systems have been through a lot of advancements in the last few years to make them smaller and more easily installed, they can still involve a large amount of work. This is due to the scale of building works and pipe runs involved, which can also result in the installation being relatively expensive.

Thinking of changing to an electric boiler? Our guide covers the pros and cons of electric Vs gas boilers.

Factors that influence the time it takes to install a new boiler

Numerous factors affect the time it takes to install a new boiler, and it’s important to understand what these are if you wish to avoid being without water or heating for lengthy periods of time.

We’ve listed some of the factors that affect the timing of installing a new boiler below.

Regulations for gas safety have not been met

Your engineer could discover a number of issues with your heating system that means that your heating system doesn’t meet the Gas Safe regulations. 

However, a common issue with heating systems over 15 years old is an inadequately sized gas supply pipe. Previously, a 15mm pipe was sufficient. However, the most recent regulations require a 22mm thick pipe. The best way to explain this is the larger the pipe, the more volume of gas can travel to the new boiler. The new regulations stipulate certain minimum pressures need to be at the new boiler for safe operation. 

If this is found to be an issue, another half a day could be added to the time taken to install a new boiler in your home. 

Another issue may be the distance of your boiler’s flue pipe from doors and windows, which again will increase the time it takes to install your new boiler. There are many different ways in which this can be resolved. This may result in an extension piece for the flue which means it may look different externally or there may be minor building works.   

MagnaCleanse, power flushing or chemical flushing

A MagnaCleanse flushes the system of harsh, unwanted materials, thoroughly cleaning the entire system. The MagnaCleanse filter also helps to collect sludge from your system for disposal. 

Our engineers prefer MagnaCleanse to both power flushing and chemical flushing, and we offer a system flush free with every installation.

A power flush is an older cleaning process for a central heating system that flushes chemicals through the system and pipes. It removes debris, dirt, rust and any other unwanted waste. This process uses an external pump to the system pump and can be quite aggressive and not suitable for all types of systems.

A chemical flush uses gravity to empty the system and refill it. The chemicals are dispersed around the system to remove residue and unwanted waste, and the system is then flushed with clean water and boiler inhibitor to protect it fully. 

Power flushing is a great tool to use if you wish to clear a boiler or a heating system, especially one boasting blockage or has sludge in the system - both of these issues can cause the radiators and pipes to run less efficiently.

Smart thermostat installation

Smart thermostats are growing increasingly popular due to their ability to make considerable energy savings on your home as well as give you greater control over the temperature of your home. 

In the majority of homes, installing a smart thermostat such as a Google Nest thermostat in place is a job that can often be completed by an engineer in less than an hour.

If you purchase smart home products, like a thermostat, with your BOXT boiler, we will install this for you for free. 

Magnetic boiler filter installation

A magnetic boiler filter is a component that is fitted to your current heating system. 

Magnetic boiler filters can be highly beneficial in prolonging the life of your heating system and keeping it energy efficient. 

The filters catch unwanted materials such as rust and stop them from travelling through your system. Without this, these unwanted materials can clot and lead to boiler problems later down the line. 

Upgrading your gas supply from meter to new boiler

When considering the installation of a new or replacement boiler, it is easy to disregard the additional elements and focus on the installation itself. However, all elements are imperative in the function of your boiler system.

One key factor to take into consideration that is often overlooked when considering the time taken to install is the gas pipework. 

Without the correct gas pipework, your new or existing boiler will simply become an unwanted ornament. 

Most modern boilers require a precise size of gas pipe for them to meet the relevant building regulations. It’s important to consider this when planning the timeline of your new boiler installation; if not, you may be met with a shock!

When is the best time to have a new boiler installed?

Although it’s sometimes impossible to pick the best time, if you can, choose the months of summer to complete a boiler installation. 


You’re less likely to miss hot water and warmer radiators for a few days or weeks, depending on the type of installation being undertaken.

How to find a professional Gas Safe engineer for your boiler installation

With next-day installation, over 10,000 five star reviews and the top boiler brands to choose from, BOXT has certified professional gas safe engineers available to install your new boiler as soon as tomorrow.

Do you have a question or query that needs answering? Our Live Chat will put you in touch with a boiler specialist who is happy to offer advice or guidance. From boiler recommendations to repair guidance - you can talk directly to a real person. 

If you’re ready to find a new boiler for your home, get a quote from BOXT today. 

Frequently asked questions

If considering a direct swap, it is important to note that boilers, tanks and cylinders come in all shapes and sizes and a variety of capacities and powers, with the pipework size for central heating being the most challenging part.

For example, your chosen space could be too wide or too narrow for a particular boiler style, which means the boiler won’t function correctly.

With this in mind, it is essential to hire the services of a professional Gas engineer, and one who is skilled in this area. 

If your boiler has reached the end of its lifespan, certain parts of the system need to be repaired, or a full swap is required, it is important to factor in the additional installation times that this can take.

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