How do I know how old my boiler is?

The most reliable route is the serial number. Every boiler has a data plate or sticker — usually behind the drop-down front flap, inside the case door, or on the side or underside of the unit. Most manufacturers encode the year and week of manufacture in that serial number, and their customer service teams (or online serial-number checkers) will decode it for you in minutes if the format isn't obvious.

Next, look for the paperwork. The Benchmark commissioning checklist — a small booklet the installer fills in on the day — records the exact installation date, and it is often tucked behind the boiler, in a kitchen drawer or with the house documents. Service stickers or a service logbook on or near the boiler also give you a good timeline: the earliest service date puts a floor under the boiler's age.

If the paperwork is long gone, the Gas Safe Register can help. Installers are required to notify new boiler installations for Building Regulations purposes, so a certificate should exist with the installation date — Gas Safe can supply a copy. Failing that, ask the previous owner or check your property purchase survey.

Why it matters: a modern condensing boiler should last 12–18 years with annual servicing, so knowing the age tells you whether a fault is worth repairing. Our boiler replacement cost guide and best boiler brands guide cover the next step if it is time.