If your boiler is showing its age — or has finally given up — understanding what a replacement is likely to cost is the first step to making a good decision. Boiler replacement is one of the larger household expenses people face, so it’s worth knowing what’s actually driving the price and where you can and can’t economise.
In 2026, the total cost of a new combi boiler installation in Kent — including supply of the boiler, all labour, and standard components — typically falls between £2,500 and £4,500. That’s a wide range, and understanding why helps you evaluate quotes properly.
What affects the cost?
The boiler brand and model is the most obvious variable. Budget-friendly options from manufacturers like Baxi and Ideal sit at the lower end of the price spectrum, while premium brands such as Worcester Bosch and Viessmann cost more to supply but often come with longer warranties and better long-term reliability records.
The complexity of the installation matters significantly too. A straightforward like-for-like swap — same boiler location, same pipework configuration — is considerably cheaper than a job that involves repositioning the boiler, rerouting pipework, upgrading to a new flue system, or converting from a different boiler type (such as a back boiler or a system boiler). Moving a boiler from an airing cupboard to an external wall, for example, adds both labour time and materials.
Additional work often runs alongside a new installation. If your existing system has no magnetic filter, most engineers will recommend fitting one to protect the new boiler. If the system is sludged, a power flush before installation is advisable. If your controls and thermostat are outdated, this is a natural point to upgrade to a smart thermostat. These additions typically add £200–£400 to the overall job.
What does a standard installation include?
A properly quoted boiler installation should include the boiler unit itself, all standard fittings, valves and pipework required for the connection, a new flue if required, commissioning of the boiler, registration with the manufacturer for warranty purposes, and Building Regulations notification via a Gas Safe registered company. You should receive a Gas Safe certificate on completion.
At David Osborne Heating, we provide written quotes that break down supply and labour separately so you can see exactly what you’re paying for.
How long does an installation take?
A standard like-for-like combi boiler swap typically takes one to two days. More complex jobs involving pipework changes or system conversions can take two to three days. It’s unusual for a competent team to take significantly longer than this on a residential installation.
What about warranties?
Most combi boilers come with a manufacturer’s warranty of between 2 and 12 years, depending on the brand and model. Longer warranties — 7 to 12 years — generally come with premium brands and may require annual servicing to remain valid. Always register the boiler with the manufacturer after installation, and keep your service records.
Frequently Asked Questions
Q: Is it worth paying more for a premium boiler brand?
A: Often yes, particularly if you plan to stay in the property long-term. Premium brands typically have better reliability records, longer warranties, and more available parts. The higher upfront cost can offset future repair bills.
Q: Can I supply my own boiler and just pay for labour?
A: Some engineers will accept this arrangement, but many won’t — partly because they can’t offer any guarantee on a boiler they didn’t supply. It also means any warranty arrangements fall to you. It’s usually better to let the engineer supply and fit.
Q: Do I need Building Regulations approval for a new boiler?
A: Yes — all boiler installations must comply with Building Regulations. Gas Safe registered companies can self-certify the work, which means the notification and certification process is handled by us as part of the job.
Q: How do I know if I need a combi or a system boiler?
A: A combi boiler heats water on demand and doesn’t need a hot water cylinder — ideal for most modern homes with one or two bathrooms. A system boiler works with a cylinder and suits larger homes with higher hot water demand. We can advise on the right type for your property.
Q: What happens to my old boiler?
A: We remove and dispose of the old unit responsibly as part of the installation. You don’t need to arrange anything separately.