1. HeatingForce
  2. Boilers

How Long Does It Take To Fit A New Boiler?

Considering having a boiler replaced, and want to know how much time to have off work?

No problem. In this 5-minute guide, we’ll explain how long it takes to fit a boiler, depending on the type of install you need.

And, we’ve added a few scenarios to consider, that will increase the time taken to fit your boiler at the end (some are a legal requirement, so can’t be ignored).

The short answer? Leading companies like Heatable can fit a new boiler as soon as tomorrow. You can get a fixed price online here, without even putting in any personal details.

Like-For-Like Boiler Swap

The first, and most common boiler installation, is a straight swap.

For instance, you have a broken combi boiler, and you want a similar combination boiler fitted in the same location.

The Gas Safe engineer will be able to use existing pipework to the boiler, and therefore, it’s a simple replacement.

Time Taken For Installation

Expect a like-for-like boiler swap to take 1 day. As an example, leading boiler installation company Heatable can fit new boilers as soon as tomorrow.

Check out their boiler size calculator to see what boiler you need, price, and timescale.

This could take up to 1.5 days if the pipework from the old boiler doesn’t match directly with the new boiler.

New Boiler, In A New Location

If you want a similar boiler fitted, but in a new location, this is going to add on some time.

The engineer will need to run additional pipework, and cap off existing gas pipework.

Also, they may need to adjust sections of your existing heating pipework, in order for all the radiators to get hot.

Time Taken For Installation

Expect a new boiler fitted in a new location to take 1.5-2 days.

The further away from the original location you want the boiler moved, the more time it will take, and the more it will cost to fit the boiler.

System Upgrade

System upgrades are more complex than a simple installation. So, the time taken is always going to be more than a like-for-like swap.

If you want to change one type of boiler for another, this is going to be classed as a system upgrade.

This could be swapping a combi for a system boiler, a back boiler for a combi, and so on.

But, why does it take longer?

Let’s say you want to switch from a system boiler (that has a cylinder) to a combi (that doesn’t require a cylinder).

In this case, the engineer will need to remove the cylinder and re-pipe the central heating system.

If you’re going the other way (combi to a system), then the extra time will be due to the cylinder and additional pipework needing to be installed. You can get a price for an upgrade using this form. Or, read our guide to upgrading to a combi boiler.

Time Taken For Installation

Expect a system upgrade (i.e. switching from one type of boiler to another), to take 2.5-3.5 days depending on the complexity (and access) of the installation.

Considerations When Determining Time Taken For A Boiler Replacement


When you fit a new boiler, you’ll want the system to be flushed out.

A hot flush with chemicals will get rid of most of debris in your heating system. However, a powerflush will get rid of slightly more.

The downside to a powerflush is it can put excess pressure on old radiators, pipework, and copper joints. If your heating system is old, this can sometimes lead to leaks.

It also takes much longer.

We’d suggest using a hot flush, but fitting a magnetic system filter.

This will catch any debris in the system (such as rust on the inside of radiators) that circulates around the system.

Time Taken

A hot flush will only take 1-2 hours, and won’t affect any of the timeframes mentioned above for boiler swaps.

However, a powerflush could take as long as 8-hours depending on how many radiators you have. This could add an extra 0.5-1 day onto the installation time.

Gas Mains Upgrade

Some older boilers only need 15mm pipe to supply enough gas to allow them to operate.

Newer boilers and updated Gas Safe regulations means pipework needs to be 22mm, as a minimum.

Let’s skip the complexity, but this can sometimes need to be 28mm, and even 35mm depending on the length of the gas run.

If your gas run isn’t up to standard, it needs to be upgraded, and this takes additional time.

Time Taken

This could take anywhere from a few hours, to a few days. A gas run that needs a minor upgrade won’t add on extra days to your boiler install.

However, it’s worth having a boiler engineer come and inspect your property and gas run before booking time off work.

They must upgrade this pipework to a legal standard before signing off your boiler as being safe.

What’s Next?

Ready to get boiler quotes, and an accurate timeframe for fitting? You can do that right now, here.

Thanks for reading our 5-minute guide to determine how long it takes to fit a new boiler.

Got questions? Leave a comment below and we’ll get back to you as soon as possible.

Avoid Expensive Breakdown Costs
Boiler Replacement Promise: If it's under 7 years old and we can’t repair it, we’ll replace it.
Try YourRepair. From £8/mo
All plans include: annual boiler service, all parts and labour, unlimited support and 24hr helpline.
Leave a comment

Your email address will not be published. Required fields are marked *