Worcester Greenstar servicing: what keeps the guarantee valid

A Worcester Bosch Greenstar guarantee only stays valid if the boiler is serviced every year by a Gas Safe registered engineer and the record is kept. Worcester treats the annual service as a condition of the guarantee, so a missed year can undermine cover that runs up to twelve years on the flagship models.

How often does a Worcester Greenstar need servicing?

Once a year, every year. Worcester Bosch sets annual servicing as a condition of its guarantee, and its own guidance is plain that the service must be completed each year to keep the guarantee valid. That holds across the current Greenstar range, from the entry 2000 through the mid 4000 to the flagship 8000 and the heat-only Ri. Miss a year and the customer can weaken cover they have already paid for in the price of the boiler, so it is worth flagging at handover and at every visit after.

Who is allowed to do the service?

A Gas Safe registered engineer, for any gas Greenstar. Worcester is specific about it, and sets the same bar on the oil side with an OFTEC registered technician. The company that originally installed the boiler can do it, or the customer can use Worcester's Find an Installer tool to reach a Worcester Accredited Installer. What matters is that the work is signed off by someone on the register and the record is kept, because that record is what Worcester can ask to see if a claim is ever made.

How long is the guarantee on each Greenstar?

It depends on the model and how it was registered. Worcester's current guarantee lengths, as published in 2026, run from seven years at the entry end up to twelve years on the flagship, and the longer terms are unlocked by registering the boiler with a Greenstar System Filter fitted.

• Greenstar 2000: a seven year guarantee. A system filter is good practice but does not extend this range.
• Greenstar 4000: seven years as standard, rising to eight with a Greenstar System Filter and up to ten through the accredited-installer route.
• Greenstar Ri and CDi Compact: seven years as standard, up to ten when registered with a Greenstar System Filter.
• Greenstar 8000: eight years as standard, up to twelve with a Greenstar System Filter, depending on the exact model in the range.
• The System Filter Micro does not unlock the extended terms, so check which filter is fitted before you promise a length.

Whatever the badge says, the guarantee only holds if the annual service is done, so the length on the box is a ceiling rather than a promise. When a customer wants the exact figure for their boiler, Worcester's guarantee checker reads it from the serial number.

What can void a Greenstar guarantee?

A missed annual service is the most common way. Because Worcester makes the yearly service a condition, a gap in the service history is the first thing that can undermine a claim. Beyond that the usual manufacturer terms apply: the boiler has to be installed and commissioned correctly, registered in time, and maintained to Worcester's instructions, and the service record needs to be available for inspection if asked. None of this is exotic. It is the ordinary paperwork of a well-run job, which is why it slips.

What should you record at every service?

The service that protects the guarantee is only as good as the record behind it. Manifold builds the service record and CP12 from the check on your phone, reads the make, model and serial off the data plate with PlateScan, and keeps each appliance's service history in one place, so the annual dates are there the next time the customer or the manufacturer asks.