A new boiler is a big-ticket, once-a-decade purchase. Here is what separates a proper installer from a corner-cutting one, before you sign anything.
Start with Gas Safe registration — it is not optional
Anyone working on a gas boiler in the UK must be Gas Safe registered by law. It takes a minute to check any engineer or company on the Gas Safe Register directly, and it is the single most important check in the entire process — do it before agreeing to anything, not after work has started.
A proper quote follows a proper survey
Be wary of a fixed price given without anyone seeing the property. Boiler type, output, flue routing and any pipework changes all affect the real cost, so a legitimate installer surveys the property first and puts a fixed price in writing afterwards — not a verbal estimate over the phone that can move once the engineer is on site.
Ask about manufacturer accreditation, not just the brand name
Most manufacturers offer a longer warranty when a boiler is fitted by an installer specifically accredited by that manufacturer, on top of the shorter standard warranty any Gas Safe engineer's installation qualifies for. If a long warranty matters to you, ask which manufacturer schemes the installer holds accreditation with, rather than assuming the brand's maximum warranty applies automatically.
Check what is actually included in the price
A clear quote should state the boiler make and model, its output, what happens to your existing pipework and controls, old boiler removal and disposal, and the total fixed price. If a quote is vague about scope, ask for it in writing before booking a date.
Confirm the paperwork you should receive
After installation, you should be given a completed Benchmark commissioning checklist (required by most manufacturers to validate the warranty) and confirmation that the work has been notified through the Gas Safe scheme for Building Regulations compliance. If an installer cannot explain either of these, that is worth asking more questions about before booking.
Frequently asked questions
How do I check if an installer is Gas Safe registered?
Search their name or business on the Gas Safe Register website, which is free and public. Every legitimate installer will be listed with their registration number and the type of gas work they are qualified for.
Should I be suspicious of a price quoted without a survey?
Treat it with caution. Boiler type, output and any pipework changes genuinely affect price, so a fixed figure given without seeing the property is either a rough estimate that can change, or a sign the installer is not assessing the job properly.
Does a longer warranty always mean a better installer?
Warranty length depends on manufacturer accreditation as much as the installer's general competence. It is one useful signal among several — ask about it, but also check reviews, Gas Safe registration and how thoroughly they survey the property.