When you're preparing to upgrade or replace your boiler, one of the biggest concerns is how long you'll be without heating and hot water. The good news is, with proper planning and a qualified installer, most boiler installations are completed quickly and with minimal disruption. In this guide, we break down the typical timeframes, what can affect them, and what you can do to help the process run smoothly.
How long do boiler installations take?
Boiler installations typically take between one and three days, depending on the complexity of the job. Before any work begins, a heating engineer will carry out a site visit or video survey to assess your current system and discuss your requirements. This makes sure the installation is tailored to your property, helping avoid delays and unexpected costs.
Once installation begins, the engineer will isolate your heating system, remove the existing boiler, and begin preparing the space for the new unit. This includes pipework modifications, flue adjustments, and potentially adding new fittings or controls.
Like-for-Like Boiler Swap (1 Day)
If you're replacing your existing boiler with the same type in the same location (e.g. a combi for a combi in the kitchen), this is the simplest and fastest type of installation. Since much of the infrastructure is already in place, including the pipework and flue system, the job can usually be completed in a single day.
This is often the case for relatively modern systems that are being replaced due to age, wear, or inefficiency. Provided no major issues are discovered, your heating and hot water can be back up and running by the evening.
Changing Boiler Type (2 to 3 Days)
Upgrading from a regular boiler or system boiler to a combi boiler is increasingly popular, especially for households wanting to free up space. However, changing the boiler type requires additional work such as:
- Removing hot water cylinders or cold water tanks
- Installing new pipework
- Adjusting or replacing the flue
- Wiring in new controls or thermostats
These conversions generally take two to three days, depending on the size of the property and how accessible the components are. The first day is typically spent removing the old system and preparing the new one, with installation and testing on subsequent days.
Relocating the Boiler (Extra 0.5 to 1 Day)
If you're having the boiler installed in a different part of the home, this adds to the timeframe. Moving a boiler from a kitchen to a loft, for example, means running new pipework, modifying the flue, and ensuring the new location meets building regulations.
While not always necessary, relocation is common when homeowners are undertaking renovations or want to maximise living space. Relocating the boiler can add half a day to a full day to the job.
Upgrades and Extras (Add-On Time)
Many homeowners use the opportunity to make additional improvements to their heating system. These can include:
- Installing smart heating controls (e.g. Hive or Nest)
- Adding thermostatic radiator valves (TRVs)
- Fitting a magnetic system filter
- Carrying out a full powerflush to remove sludge and improve efficiency
While these upgrades don’t usually add more than a few extra hours, they can increase overall installation time if combined.
Factors That May Affect the Timeline
Although heating engineers aim to stick to the agreed schedule, a few factors can influence how long your installation takes:
- Age and condition of the existing system
- Unexpected complications like blocked pipes, asbestos near flues, or old electrics can add delays.
- Access to the boiler location
- Tight spaces, high walls, or restricted lofts can slow down installation.
- Parts availability
If special fittings, flue extensions, or boiler models are required, lead times from suppliers can add delays.
System testing and safety checks
All installations must be thoroughly tested and commissioned. Your engineer will check for gas leaks, proper pressure, and correct operation of all heating controls.
Book a boiler installation in Blackheath, Charlton, Greenwich and Welling
McGrath Heating Services Ltd provides professional boiler installation services. Call us on 01202 403 666 or fill out our contact form to get started with your free quote.
