One of the most common questions we get asked is ‘How long does it take to replace a boiler in the UK?’. On average, installing a new boiler takes anywhere from six hours to four days.
It’s a fair request really — the fitting of a boiler does take a bit of a toll on household life. You might be worried about not having the use of the central heating and hot water during the installation.
Here’s the honest answer: there’s no such thing as a one-size-fits-all solution. The installation time will depend on a few variables — the boiler you’re having fitted, whether it’s a different boiler installation, or whether you’re having it fitted in a different part of the home.
Boiler Replacement and Boiler Installation Time
Boiler installation and replacement times will be affected by a variety of factors. The boiler type, the boiler position, and whether the installation includes an upgrade of an existing unit or a replacement will also dictate the installation duration.
The installation of a brand-new boiler will take 4-6 hours if it is a straightforward swap; however, it will take 4 days if it is a complex installation. If it’s a brand-new combi boiler that you’re fitting in the existing position, the boiler installation will be short.
The installation will be slightly longer if you’re replacing a system boiler with a combi. Also, if the position of the boiler needs changing, or if the central heating system needs updating. The condition of the pipework and any extra fittings that need fitting will also affect the installation duration.
How Long Does It Take to Replace a Boiler?
Generally speaking, installing a new boiler takes anywhere from six hours to four days. However, the period it will take to replace a boiler will be dependent on the installation and the installation’s complexity.
- Like-for-like boiler swap (such as replacing an existing old combination boiler with a brand-new unit in the same position): 4-6 hours.
- Boiler changeover (for example, converting a system boiler to a combi boiler): 1-2 days.
- Relocation of the boiler into a different position: 1-3 days
- Full installation of a central heating system will take: 3-4 days.
Factors Influencing the Boiler Installation Duration
There are several factors that will affect the duration of a boiler installation:
- Boiler type: Installation of a combination boiler is quicker than system boiler conversion.
- Location: Relocating a boiler to a different place involves additional time for the installation of new pipes and electrical work.
- Pipework condition: Old or damaged pipes might need replacing, adding time.
- Further work including making structural adjustments, such as drilling a flue or fitting a condensate pipe, will take more time.
Each installation will be unique. And therefore the duration will be varied. Your installer will be able to let you know the exact time estimate once they’ve evaluated your installation.
What Does a Boiler Installation Involve?
Interested in how a new boiler installation goes? Let’s take it a step at a time:
Arranging the installation
You will schedule the installation of the boiler first. The installer might need the details of the home and the boiler you own. They will at times request pictures of the existing installation beforehand.
Removing the old boiler
On the day the engineer will arrive and present their Gas Safe ID. They will switch the gas, water, and electricity off and then take great care in removing the old boiler. They will also take away any extra pipes and tanks if it’s being relocated.
Fitting the new boiler
Finally, they fit the boiler in the original position or a new position. They will fit the connections of the water, the gas, and the electricity. Then they will also install any extra fittings including a flue and a thermostat.
Testing the system
Once fitted, the engineer will also test the boiler. They will check for leaks and make sure the heating and hot water work properly. They will also balance the central heating system so that it operates correctly.
Cleaning up and disposal
Finally, the old boiler and any packaging will be taken away. The engineer will depart with your home in the state it started in — except that it will be a bit cosier!
How Long Does It Take to Replace a Combi Boiler?
How long it will take to replace a combi boiler varies with the installation type. If it’s a straightforward swap, it’s a short period of time. However, if you’re relocating the position or changing the system type, it will be a longer duration.
Simple Combi Boiler Swap: 4-6 Hours
If you’re replacing a brand-new boiler with an existing old combi boiler in the same position, it’s a reasonably simple operation. The installer will:
- Replace the old boiler.
- Get the new fit
- Drain the system in preparation for any debris.
- Install a thermostat.
- Test everything.
This process usually takes 4 to 6 hours and is typically completed within a day.
Relocation of a Combi Boiler: 1-2 days
If you need the boiler moved to a different location, it will take a little longer. This is because the engineer will need:
- Install the new water and gas pipes.
- Drill through walls for pipe connections.
- Redirect the wiring and thermostatic cable.
How long it will take: 1-2 days, depending on how far they need to move it.
Installing a New Combi Boiler from Scratch: 1–2 Days
If it’s an installation of a combi boiler for the first time, the installation will be identical to a relocating installation. The installer will:
- Set connections of water and gas supplies.
- Install new pipework.
- Install radiators if necessary.
Duration of installation: 1-2 days for a typical installation. Depending on whether a whole central heating system installation is carried out, it will take 1-2 weeks.
How Long Does It Take to Replace a Combi Boiler with a System Boiler?
It will normally take 2-3 days to swap a combi boiler with a system boiler. It’s a larger installation because system boilers work differently — they need a cylinder to store the heated water. This involves extra pipework, wiring, and fitting the cylinder, normally in an airing cupboard or similar.
Here is how the process goes:
Day 1: Removal of the old combi boiler and starting the installation of the new connections and pipes.
Day 2: Installation of the system boiler and the hot water cylinder.
And
Day 3: (if required): Check it all out — that the heating and the hot water system are working correctly and the system is safe.
How Long Does It Take to Replace a Gas Boiler?
It will normally take 4-8 hours if it’s a simple installation to replace a gas boiler.
If you’re changing an existing boiler with a brand-new identical-type boiler in the same position, it’s the quickest option. The installer will:
- Remove the old boiler.
- Install the new one.
- Connect it with your gas and water line.
- Test it all to ensure it operates safely.
But if anything does not go right that we’re not anticipating — say, the pipework needs repairing or the flue needs modernising — it will take a few extra days. Otherwise, it’s done in a day for most houses.
How Long Does It Take to Replace a Back Boiler with a Combi Boiler?
It will normally take 2 days to replace a back boiler with a combi boiler. It’s a harder-than-average boiler replacement because the back boiler will typically be located behind the fire. And will ventilate through the chimney. Here’s how the installer will proceed:
- Remove the back boiler. This will take a while because it is often built into the wall.
- Relocate the new combi boiler to a different position, either in the kitchen or the airing cupboard.
- Install a new flue (since combi boilers use a horizontal or a vertical flue instead of a chimney).
- Upgrade the pipework to suit the updated installation.
How Long Does a Full Central Heating System Upgrade Take?
A typical installation of a whole central heating system will take 3-5 days. It will be based on the size of the home and how much needs to be done. The bigger the home and the larger the project, the longer it will take.
- Small houses usually take 3 days.
- Larger residences with extra bathrooms or complex systems will take an interval of 5 days.
A registered Gas Safe expert will inspect your home, and recommend the ideal boiler. A system boiler if you will be requiring a higher output of hot water. Or a combi boiler if space becomes an issue — and offer a clear works schedule.
How Can I Speed up my Boiler Installation Time?
Need a faster boiler installation? Here’s how you can help:
- Choose the same boiler type. A like-for-like exchange will be quicker compared with a system change to a combi.
- Clear the space and leave the area near the boiler and the pipework free and accessible to the engineer.
- Pre-book a Gas-safe installer. Don’t leave yourself at the mercy of last-minute postponements with a pre-booking.
- Discuss the specifics in advance. Agree on the position of the new boiler and whether you will need any additional work, such as new flues and pipe replacements.
Being pre-qualified will allow the installer to proceed immediately with no further delay.
Find a Professional Gas Safe Registered Engineer
Always use a registered Gas Safe engineer for any installation of a boiler, maintenance of a boiler, and any repairs of a boiler — it’s not a good idea; it’s the law. They’ve been specially trained to fit, repair, and service gas appliances safely. You can ask the engineer to show you the Gas Safe ID card. Or check them on the government-approved Gas Safe Register website.
Not only will a competent engineer fit your boiler properly, but they will also get it tested and ensure that it’s working properly and safely.
Today Is the Perfect Time to Replace an Old Boiler
If you’ve got an old, outdated, or faulty boiler, now is the best time to replace it. The brand-new boiler will not just reduce energy bills, but keep the home properly heated and also minimise carbon emissions. And if you’re qualified, you may also get it at no charge with the free boiler grant with the ECO4 scheme.
Replace it in the fall so that you’re prepared for the cold weather. Today’s boilers also have smart controls that will ease the experience of heating. Installation will be 1-3 days depending on how you’re configured. So, do not wait until the boiler fails—book in advance and get cosy.
FAQs
Fitting a brand-new boiler normally takes 1-3 days’ duration. This will depend on the boiler and whether it needs to be moved to a different position. Or whether it will be a direct swap with the same model.
It will if it includes the fitting of brand-new pipework. But good fitters will try and keep the area clean and clear it once the installation has been carried out.
Fitting a brand-new boiler will take 1-3 days’ time. The exchange with an identical boiler will be quicker. Relocating the boiler or replacing it with a combi boiler will be slower.
Yes, most replacements of a boiler will also include a thermostat. Perhaps a brand-new, smart one — so that you will have more control of the heating and it will aid with efficiency. So, be sure and ask the installer.
Yes, the installers will typically need access to radiators everywhere. This will enable them to balance the system and ensure that it will be working effectively with the new boiler.
