If you’re planning to replace or upgrade your boiler, one of the most common questions you might have is, “How long does it take to install a boiler?” The installation process can vary depending on several factors, including the type of boiler, the complexity of the installation, and whether additional work is needed. In this guide, we’ll walk you through the key aspects that determine how long a boiler installation might take.
Factors That Affect Boiler Installation Time
Several factors influence the time it takes to install a new boiler. Here are the main ones:
1. Type of Boiler Being Installed
Different types of boilers come with different installation requirements:
- Combi Boiler to Combi Boiler Replacement – This is the quickest and simplest type of installation, typically taking 4-6 hours.
- System Boiler to System Boiler Replacement – Since system boilers require a hot water cylinder, the installation usually takes 1-2 days.
- Conventional Boiler to Combi Boiler Conversion – This is a more complex job because it involves removing water tanks and making additional pipework adjustments. Expect this to take 1-2 days.
- Back Boiler to Combi Boiler Upgrade – Back boilers (found behind fireplaces) require full removal and reconfiguration of pipework, making this one of the longest installations at 2-3 days.
2. Location of the Boiler
If your new boiler is being installed in the same location as your old one, the process is faster. However, if you’re moving it to a different room or a different part of the house, additional pipework and modifications will be required, which can add an extra half a day to a full day.
3. Gas Supply and Pipework Adjustments
If your new boiler requires an upgraded gas supply pipe (which is common for modern high-efficiency boilers), this can add extra time. Your heating engineer may need to run a larger gas pipe from your meter to the boiler location, which can take a few additional hours or even a full day in complex cases.
4. Flue Installation and Regulations
The flue is responsible for venting waste gases safely outside. If the existing flue location is suitable, this step is straightforward. However, if a new flue system needs to be installed or rerouted, this can extend the installation time by a few hours.
5. Additional Upgrades or Adjustments
Some homeowners choose to upgrade other parts of their heating system alongside a boiler installation. This can add extra time:
- Adding new radiators – Can add an extra 1-2 days, depending on how many are being installed.
- Installing a smart thermostat – Takes around 1-2 hours.
- Power flushing the system – This process removes sludge and debris from the pipework and radiators, ensuring the new boiler operates efficiently. A power flush takes around 4-6 hours.
6. Unforeseen Issues
Occasionally, unexpected problems arise during an installation. Common issues include:
- Old pipework needing replacement
- Blockages in the heating system
- Electrical work required to meet safety regulations
These unforeseen issues can extend installation time by several hours to a full day.
Typical Boiler Installation Timelines
| Type of Installation | Estimated Time |
| Combi to Combi Swap | 4-6 hours |
| System to System Swap | 1-2 days |
| Conventional to Combi Upgrade | 1-2 days |
| Back Boiler to Combi Upgrade | 2-3 days |
| Adding a Smart Thermostat | 1-2 hours |
| Power Flushing the System | 4-6 hours |
What to Expect on Installation Day
- Engineer Arrival & Safety Checks – The engineer will assess the area and ensure safety protocols are followed.
- Removal of the Old Boiler – This step usually takes a couple of hours.
- Installation of the New Boiler & Pipework Adjustments – This is the main part of the process and varies in duration depending on complexity.
- Flue & Condensate Pipe Installation – Ensuring safe ventilation and drainage.
- System Testing & Safety Checks – The engineer will test the boiler and entire heating system to confirm it’s working correctly.
- Handover & Explanation – The engineer will show you how to use your new boiler, adjust settings, and schedule maintenance.
Need a Professional Boiler Installation in Earls Court?
If you’re considering a boiler installation in Earls Court, our expert team at West London Plumbing is here to help. We provide efficient, reliable, and professional installations with minimal disruption to your home. Get in touch with us today for a free consultation and quote!