How Long Does a Boiler Installation Really Take? July 25, 2025 Getting a new boiler installed is an essential upgrade for your home, but one of the most common questions homeowners ask is, how long will it actually take? Whether your boiler has broken down or you're planning a proactive replacement, having a realistic idea of installation times helps you plan your day and reduce any surprises. Factors That Affect Installation Time Straight Swap: 1 Day (4 to 8 Hours) This is the fastest and most straightforward type of boiler installation. If your current system is a combi boiler and you’re simply replacing it with a newer model in the same location, the job can typically be completed within a standard working day. These installations are often completed in as little as 4 to 8 hours, especially if the existing pipework and flue are in good condition. The work includes disconnecting and safely removing the old boiler, preparing the site, connecting the new boiler to the existing pipework, and performing all necessary testing. Since there’s no need for extra plumbing work or additional fittings, installation is relatively smooth and predictable. Once everything is in place, the heating engineer will complete gas safety checks, adjust your heating controls, and issue the relevant certification before showing you how to use your new boiler. System Conversion: 2 to 3 Days from a traditional heating system to a combi boiler is more complex. This often applies to homes that currently have a heat-only boiler with a separate hot water cylinder and cold water tank. A combi boiler eliminates the need for these components, but that means more time is needed to remove them and repurpose the existing pipework. In most cases, the installer will remove tanks from the loft and airing cupboard, adjust the plumbing to handle hot water on demand, and may need to install additional safety features like pressure relief valves. Any redundant pipework may also be removed or sealed off. This type of conversion usually takes between two and three days, depending on your property layout and the condition of your existing system. Boiler Relocation: 2 Days or More If you’re having the new boiler fitted in a completely different part of the house—such as moving it from the kitchen to a loft or utility room—this will significantly extend the installation time. Rerouting the gas supply, water pipes, and heating flow and return pipes is a time-intensive task, especially in older homes where access may be restricted. Relocating a boiler may also involve extending or rerouting the flue, drilling through external walls, and adjusting the electrics. For safety and efficiency, the boiler’s new position must meet current building regulations and ventilation standards. In most cases, relocation adds an extra one or two days to the job, making it a two-day project at minimum. If structural alterations or additional electrical work is required, it could take even longer. Back Boiler Replacements: 3 to 4 Days Back boilers are outdated systems that were often fitted behind fireplaces and can be difficult and time-consuming to remove. If you're upgrading from a back boiler to a modern combi or system boiler, the process is one of the most involved types of installation. Removing the back boiler typically requires dismantling parts of the fireplace and making good any brickwork or decorative elements afterwards. Once removed, the engineer must fit a new boiler elsewhere in the property, which will involve fresh pipework, updated controls, a new flue system, and potentially a power flush of your central heating. Because of the added complexity and safety requirements, this type of upgrade usually takes between three and four days. However, once complete, you’ll benefit from much better efficiency and simpler maintenance in the future. Additional Work That Can Extend the Job Some installations require extra work, which can affect the timeline. These include: Power flushing the system to clear sludge and debris Upgrading gas pipework to meet modern safety standards Fitting smart thermostats or zoning controls Installing magnetic filters or system protection devices Your heating engineer should explain any of these requirements during the initial survey. How to Prepare and What to Expect A professional boiler fitter will carry out a pre-installation survey to identify any complications ahead of time. On the installation day, be prepared for some disruption, such as temporarily switching off the heating and hot water. However, experienced boiler installers work efficiently to minimise downtime, especially when you're left without heating in colder months. If time is important, say you're moving house or have vulnerable occupants, mention this early, as some installers can adjust their scheduling or split the job over multiple visits for flexibility. Planning a Boiler Installation in Chesterfield? Spencer Plumbing & Heating offers reliable boiler installations with clear timelines across Chesterfield. Whether it's a same-day combi swap or a full system upgrade, we’ll give you an honest estimate and keep everything on schedule. Call us on 01246 912132, 01433 410213, or 07891 817026, or fill out our contact form to get started.
