Eco Happy (Solar Expert)

Published February 23, 2024

If you’re in the market for a new boiler, you may be wondering, “How long does it take to fit a new boiler?”.

This one is tricky to answer because it depends on the type of installation you’re looking at. On top of that, you’ll also need to prepare the space properly to ensure a smooth installation. And you’ll need to keep in mind that some factors delay the process.

In this article, we’ll explore how long it takes to install a boiler, factors that affect installation time, and how to prepare your space.

Understanding Boiler Installation Time

On average, the time it takes to complete a new boiler installation is between 6 hours to 3 days. While this is quite a big time difference, there are a lot of factors at play. It’s a complex process that has to be done professionally.

Let’s take a look at the types of installations and how long they take.

Swapping boilers

If you’re going for a boiler swap, you could be looking at 4 to 6 hours for installation. It’s the easiest process, and usually only requires draining the old boiler system, disconnecting the electricity, and swapping the new one in. A straight swap is the simplest process.

However, it could be delayed if the pipework isn’t the right size.

If the pipes are too big, you could be looking at adding another day for resizing and refitting.

If the pipes are too small, you could be looking at a day or more. This one takes longer because it involves altering the pipework layout.

Combi boiler installation

If you’re upgrading from a system boiler to a new energy-efficient combi boiler, you can expect to wait around 2 days until you can start enjoying the perks of your new boiler.

Combi boilers have different requirements, so it’ll take a while to reroute circuits from the central heating system to your new combi boiler.

If you’re just replacing combi boilers, the process shouldn’t take longer than 4-8 hours.

But if you’re swapping a different type of boiler with a combi boiler, the process is more complex.

It usually involves removing the old boiler, the hot water cylinder, and the cold water tank. Once that’s done, the combi boiler can be installed. Then, everything has to be reconnected.

A combi boiler will also require new pipework and electric work and has to be in a ventilated area.

Make sure you read over our combi boiler installation guide for clear instructions on the entire process.

Gas boiler installation

This type of boiler takes around 1 – 3 days to install.

If you’re simply swapping from one gas boiler to another, the process takes around 4-8 hours.

If you’re switching from another type of boiler, you’ll have to remove old tanks. You’ll also have to add new gas pipework and make sure the system passes all of the necessary tests.

New boiler relocation

Boiler installations take a while, and new boiler relocation isn’t much different. The average time is around 1 to 2 days.

Because you’re moving your boiler to a new location, you’ll essentially have to set it up from scratch. So, you’ll need new pipework. You’ll also need to have the flue installed and electric work done.

And your current heating system will need new controls. This is to make sure there’s no disconnect between your new boiler and your current central heating system.

If the new location is far from the old one, you’ll have an even longer delay and may have to make some architectural changes to accommodate new pipes and electrical work.

Factors Affecting Installation Time

Let’s take a look at some of the other factors that affect the time it takes to install a new boiler system.

Type of boiler being installed

The time for installation will be affected by the type of boiler. Gas boiler, system boiler, or combi boiler, each installation varies.

Existing system doesn’t meet Gas Safe Regulations

The Gas Safety Regulations are strict guidelines to ensure that the boiler installation process is safe for the installer and that the boiler doesn’t cause harm once it’s been installed.

If the gas pipes don’t meet the legal requirements, your boiler replacement or installation will be delayed. They may also need to replace the boiler flue. All of this has to be done by a gas-safe-registered engineer.

It’s only once that’s been done that you’ll be able to get the new boiler installed.

Boiler relocation

Boiler relocation can also delay the process. Here’s what needs to be moved:

  • The pipework needs to be changed
  • The electrical power needs to be altered
  • Thermostat cables have to be relocated
  • The current heating system has to be adjusted
  • The flue will need to be moved

In some cases, you may need to do a bit of remodelling to fit a new boiler in. If that happens, you’ll also need to work with other tradespeople, which can cause further delays.

Leaks from your water supply

Before your boiler is used to heat water, you need to have a supply of water from the mains. And if you have a leak in your water supply, you’ll need to fix it up before you can install your new boiler.

Complexity of heating system

Some heating systems have additional features like multiple heating zones, underfloor heating, or control systems that take time for an installer to understand and work with.

Unexpected issues

Sometimes, some issues pop up that you just weren’t prepared for. The engineer may forget a tool at home. You may find a sudden structural issue that wasn’t present before. Maybe they sent you a combi boiler when you wanted a different type of boiler.

Whatever the case, you may experience delays you weren’t prepared for.

Experience of the installer

Installing a new boiler isn’t easy to do. If the engineer installing your new boiler or replacing your old boiler isn’t familiar with the system, or doesn’t have as much experience, you may see a delay in installation times.


Once the boiler is in place, they’ll have to test it to make sure it passes all of the rigorous tests in place to ensure it’s safe.

Engineers do a good job of making sure the tests go smoothly. But you may find yourself in a scenario where the boiler doesn’t pass the tests. If that happens, you’ll have to either wait for a new one or seriously consider moving it, which can cause further delays.

How To Prepare Your Space For Installation

If you want to minimise delays for your boiler replacement or installation, you’ll want to prepare the space where your boiler will go.

Clear the space around your boiler

Removing any boxes, furniture, or other obstacles is crucial. Engineers need space to work in, so the easier it is for them to move around, the faster the work will get done.

Turn off the power and water connection

Unless you want the engineer to get a nasty shock, you’ll want to turn off your power supply. On top of that, you’ll have to find the shut-off valve and open it to reduce the chance of leaking.

Expect disruptions

Because you’ve turned off your water and power, it may take a while for those two to come back. On top of that, it may take a few hours for your new boiler to kick in, so you may experience a longer delay than you may have initially thought.


Can a plumber install a new boiler?

A plumber can work on your heating system, like the radiators and pipework. But you shouldn’t let them handle your boiler. For one, they don’t have the right qualifications. Second, they’re not experienced with handling boilers! It is best to call on the experts, like Eco Happy, for guidance.

What happens with a new boiler installation?

If you’re saying goodbye to your old boiler and hello to a new one, you may be wondering what to expect. For one, your installer should connect the boiler via pumps and pipes. These connections should lead to your water outlets, radiator, and cold water mains supply.

If you have a regular boiler instead of a combi boiler, they’ll have to connect the hot and cold water storage tanks too.

Do you need to change the pipework for a new boiler?

It’s not definite, but if you’re replacing an old boiler with a new one, there’s a good chance that you’ll need to get your pipework replaced as well.

Is it better to repair or replace a boiler?

It’s a personal preference, but here are some things to consider:

A new boiler can be more energy efficient. The initial cost is high, but the money you save in the long run is much higher.

If you don’t like change, you can repair your boiler. But bear in mind that you’ll have to replace it eventually. So why not now?

Final Thoughts

Swapping out your old boiler for a new one is good for your household and the environment – especially if you’re switching to an eco-friendly combi boiler.

Whatever the case, we hope this guide answered your questions and prepared you for the installation process! Eco Happy is here to help, so don’t hesitate to get in touch if you want to learn more!

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