A ten or twelve year warranty is one of the most valuable parts of a boiler purchase, and one of the easiest to lose. Most invalid claims we see are not caused by anything dramatic. They are caused by a missed service, a missing commissioning record, or an installation carried out by someone who was not accredited to offer that warranty length in the first place.
This guide explains what a manufacturer warranty covers, what it never covers, and the handful of things you must actually do to keep it alive.
Warranty length depends on who fits it
Manufacturers offer their longest warranties only through accredited installer schemes. The same appliance fitted by a non-accredited installer typically carries a shorter standard warranty. This is not a sales device — it exists because manufacturers want their appliances commissioned properly, and accreditation requires training and audit.
As a Vaillant Advanced Installer we can register extended warranty terms that a non-accredited installer cannot offer on the same boiler. When comparing quotes, check the warranty length in writing, not the one on the manufacturer's website, because the website figure is usually the accredited maximum.
What a warranty covers and what it does not
| Item | Usually covered | Notes |
|---|---|---|
| Failed PCB, fan, gas valve, pump | Yes | Manufacturing or component failure |
| Primary heat exchanger | Yes | Often the longest-covered part |
| Labour for a warranty repair | Usually | Check — some cheaper warranties are parts only |
| Damage from system sludge or debris | No | The most common rejection reason |
| Limescale damage | No | Hard water areas need appropriate treatment |
| Frozen condensate pipe | No | An installation and lagging issue, not a fault |
| Damage from incorrect system pressure | No | Owner maintenance item |
| Consumables and seals | No | Wear items replaced at service |
| Faults where no annual service is evidenced | No | Voided by the missed service condition |
The annual service condition
Almost every extended warranty requires an annual service, carried out by a competent registered engineer, within a defined window around the anniversary of commissioning. Miss it and the warranty typically lapses — not for that year, permanently.
The service must be recorded. A verbal confirmation is worthless at claim time. Keep the benchmark or service record in the manual, and keep the invoice. Manufacturers routinely ask for both. We keep service records for our customers and remind them when the anniversary is approaching, which removes the most common cause of a lost warranty.
The paperwork you must actually have
- The commissioning or benchmark checklist, completed and signed at installation.
- Warranty registration confirmation from the manufacturer — usually done within thirty days of installation.
- Building Standards notification for the appliance installation, which in Scotland the installer arranges through their competent person scheme.
- The Gas Safe registration record for the work.
- An annual service record for every year since installation, with no gaps.
- Water treatment evidence: inhibitor dosing, and a magnetic filter fitted and cleaned at each service.
System cleanliness is the real gatekeeper
The single most common reason a warranty claim is refused is debris. Manufacturers require the system to be cleaned before a new appliance goes on, dosed with inhibitor, and protected by a filter. If a heat exchanger blocks with sludge from a twenty-year-old circuit that was never cleaned, that is not a manufacturing fault and it will not be covered.
This is why a quote including a power flush, a magnetic filter and inhibitor is not padding — it is the condition on which the warranty rests. A quote that omits all three is cheaper today and uninsured tomorrow.
Warranty versus service plan versus insurance
- Manufacturer warranty: covers component failure on the appliance. Free with the boiler, conditional on servicing. Does not cover the rest of your system.
- Service plan: a maintenance arrangement covering the annual service, and sometimes labour. Keeps the warranty valid.
- Boiler cover insurance: a third-party policy that may cover breakdowns, controls, radiators and pipework. Useful for older appliances out of warranty, largely redundant on a boiler with a live twelve-year manufacturer warranty and an annual service.
If you have just moved house
Manufacturer warranties usually transfer with the property rather than the person, but you need the paperwork. Ask the seller for the commissioning certificate, the registration confirmation and the service history. If those are missing, contact the manufacturer with the appliance serial number — they can often confirm registration date and warranty status directly.
Then book a service straight away if the anniversary has passed. Reinstating a lapsed warranty is sometimes possible if the gap is short; after a long gap it generally is not.
Frequently asked questions
- Does a warranty service have to be done by the original installer?
- No. It must be carried out by a competent, appropriately registered engineer and properly recorded. Any Gas Safe registered engineer can do it, and we service appliances we did not install.
- I missed a service by two months. Is the warranty gone?
- It depends on the manufacturer's terms and how far outside the window you are. Some allow a short grace period. Book the service immediately and ask the manufacturer in writing — the sooner you act, the better the outcome.
- Is a longer warranty worth paying extra for?
- Usually yes, because the extra cost is modest relative to a single out-of-warranty PCB or heat exchanger repair. Just make sure you will actually keep up the annual service, or the extra length is worthless.
- Do you register warranties for the customer?
- Yes. We complete the benchmark record, register the appliance with the manufacturer and notify Building Standards, and we give you copies of everything.
Keep your warranty alive with an annual service
We service all common gas and oil appliances, record the work properly and remind you when the next anniversary is due.