ATAG currently offers one of the longest advertised manufacturer warranties for domestic gas boilers in the UK, with 12 years as standard and an option to extend cover to 18 years. Other manufacturers, including Worcester Bosch, Ideal, Viessmann and Intergas, offer up to 12 years on selected models or qualifying installations.
However, the longest boiler warranty isn’t necessarily the best choice. Registration deadlines, annual servicing, installer accreditation and additional equipment can all affect how long your boiler is actually covered.
Boiler warranties compared: UK manufacturers
The table below compares published warranty periods for selected domestic gas boilers.
| Boiler brand | Example model or range | Published standard cover | Maximum advertised cover |
| ATAG | Current domestic gas boilers | 12 years | 18 years |
| Worcester Bosch | Greenstar 8000+ | 8 years | 12 years |
| Ideal | Vogue Max | 10 years | 12 years |
| Viessmann | Selected Vitodens models | Model and registration dependent | 12 years |
| Intergas | Xclusive | 10 years | 12 years |
| Baxi | 800 range | 10 years, subject to conditions | 10 years |
| Vaillant | Selected ecoTEC models | Model dependent | Up to 10 years |
| Glow-worm | Energy / Ultimate | 7 / 5 years | 10 years |
These are manufacturer-advertised periods for selected models, not brand-wide guarantees. Longer cover may require additional products, an accredited installer, paid upgrades or specific registration arrangements. Always check the current written terms before purchasing.
It’s also worth distinguishing a boiler warranty from a guarantee on an individual component. A manufacturer might advertise lifetime cover for a heat exchanger without providing lifetime protection for the entire boiler.
Which boiler brand offers the longest warranty?
ATAG: up to 18 years
ATAG currently advertises a 12-year standard manufacturer warranty, with the option to extend it to 18 years.
The longer warranty is available through qualifying arrangements with an ATAG Partner Installer. Registration and annual servicing are required.
ATAG also advertises a lifetime replacement guarantee on its stainless-steel heat exchanger.
However, this shouldn’t be confused with lifetime cover for the complete boiler.
Its warranty terms specify separate, shorter periods for certain components, including the internal expansion vessel, ignition electrodes and flue components.
ATAG therefore offers an unusually long headline warranty, but homeowners should check exactly which components are covered throughout the full period.
Worcester Bosch: up to 12 years
Worcester Bosch offers different guarantee lengths depending on the model and installation.
For the Greenstar 8000+ range, the standard guarantee is eight years. Installing an eligible Greenstar System Filter can increase this to ten years.
A qualifying installation through the manufacturer’s installer or loyalty arrangements can extend the guarantee to twelve years.
Other models have different standard and maximum periods.
The important point is that a homeowner purchasing a Worcester Bosch boiler shouldn’t automatically expect twelve years of cover.
The actual guarantee must be confirmed against the selected model, filter and installer arrangements.
Ideal Heating: up to 12 years
Ideal’s Vogue Max range offers a ten-year standard warranty, with twelve years available through its Max Accredited Installer scheme.
The additional two years are therefore associated with a particular installer arrangement rather than being included automatically with every Vogue Max installation.
Other Ideal boiler ranges have their own warranty periods.
When comparing quotes, ask whether the installer is eligible to register the extended warranty and whether the quoted price includes everything required.
Viessmann: up to 12 years
Viessmann offers warranties of up to twelve years on selected Vitodens models.
However, its published information uses different descriptions of standard cover depending on the model, registration route and product literature.
Its general warranty schedules distinguish the initial warranty, longer cover obtained through registration and additional extensions available through the VPlus installer platform.
Some product literature also describes twelve-year standard cover for specific Vitodens 100-W models.
This makes it particularly important to confirm the terms applicable to the exact boiler and installation date rather than relying on a general brand comparison.
Intergas: up to 12 years
The Intergas Xclusive comes with a ten-year parts-and-labour warranty.
The manufacturer advertises an additional two years when a qualifying Intergas System Filter is fitted and registered correctly.
The filter must be installed at the same time as the boiler, with the relevant registration requirements satisfied.
This is an example of how a relatively straightforward installation accessory can affect the warranty period.
However, the manufacturer’s other boiler ranges may have different terms.
Baxi: up to 10 years
Baxi’s 800 range includes a ten-year parts-and-labour warranty, subject to its conditions.
The boiler must be registered within 30 days, the installation’s Benchmark checklist must be completed, and annual servicing is required.
The magnetic filter supplied with the boiler must also be fitted and maintained throughout the warranty period.
Other Baxi models have shorter warranties, including seven years for the 600 range.
Vaillant and Glow-worm: up to 10 years
Selected Vaillant ecoTEC models offer extended guarantees of up to ten years through qualifying installer arrangements. The precise period depends on the model and applicable promotion or installation scheme.
Glow-worm also offers up to ten years on selected models.
For example, its Energy range normally has seven years, extendable to ten, while the Ultimate range has five years, extendable to ten.
The extensions require qualifying registration and installation arrangements, including the specified filter where applicable.
These examples show why it’s better to compare individual boiler quotations than assume every appliance from one manufacturer carries the same warranty.
What’s the difference between a standard and extended boiler warranty?
A standard warranty is the manufacturer’s advertised cover associated with a boiler, subject to its terms and any registration requirements.
An extended warranty provides additional years of protection, sometimes in exchange for an extra payment or qualifying installation conditions.
These conditions might include using an accredited installer, fitting an approved system filter or purchasing an extension through the manufacturer’s registration scheme.
For example, Worcester Bosch’s Greenstar 8000+ has an eight-year standard guarantee but can qualify for twelve years with the appropriate installation arrangements.
The difference matters because the manufacturer’s maximum advertised warranty isn’t necessarily the warranty you’ll receive.
Ask your installer to confirm the actual period in writing before accepting the quotation.
What does a boiler warranty cover?
Most manufacturer warranties cover qualifying defects in the boiler’s materials or manufacturing, including the parts and labour needed for an approved repair.
For example, Baxi states that its boiler warranty covers the appliance and integrated controls, while Glow-worm covers qualifying manufacturing defects repaired through its authorised service arrangements.
However, the exact coverage varies.
A boiler warranty may not cover:
- Problems caused by incorrect installation.
- Sludge, limescale or contaminated system water.
- Faults in external radiators and heating pipework.
- Damage caused by freezing or inadequate maintenance.
- Unauthorised alterations or repairs.
- Normal wear, consumable components or other specified exclusions.
Not every exclusion applies identically to every brand.
It’s important to read the full warranty conditions rather than assuming that a ten-year warranty covers every possible breakdown for ten years.
What can invalidate a boiler warranty?
Missing the registration deadline
Many manufacturers require the boiler to be registered within 30 days of installation.
If this deadline is missed, the available cover may be reduced substantially.
For example, Intergas states that failure to register within 30 days can reduce the manufacturer’s warranty to twelve months. Viessmann also distinguishes its longer registered warranty periods from its shorter basic cover.
Your installer may complete registration, but you should still check that it has been processed and retain the confirmation.
Missing annual servicing
Manufacturers commonly require an annual boiler service to maintain warranty protection.
Servicing helps identify developing faults and provides evidence that the appliance has been maintained according to the manufacturer’s instructions.
The service must normally be completed by a suitably qualified Gas Safe registered engineer, with appropriate records retained.
Missing a service may affect a future claim, depending on the manufacturer’s terms.
Don’t assume the manufacturer will automatically remind you when servicing is due.
Incorrect installation or incomplete records
Boilers must be installed and commissioned correctly.
Manufacturers may require a completed Benchmark commissioning checklist, installation details and confirmation that the appliance was fitted by a qualified engineer.
Keeping your installation certificates and commissioning records can make it easier to demonstrate that the warranty conditions were met.
Poor system water quality
Contaminated heating water can cause damage to pumps, heat exchangers and other boiler components.
Manufacturers may exclude failures associated with sludge, corrosion debris or inadequate water treatment.
Some policies also require a suitable magnetic boiler filter to be fitted and maintained.
ATAG and Baxi are particularly explicit about maintaining suitable system water quality in their warranty conditions.
Is the longest boiler warranty always the best?
Not necessarily.
A longer warranty can provide valuable reassurance, especially when it includes both parts and labour.
However, several other factors determine its practical value.
Coverage: Check whether the complete boiler receives the advertised protection or whether some components have separate limits.
Qualification costs: Some extended warranties require additional equipment, paid upgrades or a particular installer.
Maintenance requirements: Understand what servicing and water-treatment records you’ll need to keep.
Claims process: Find out whether repairs are arranged directly through the manufacturer and whether any call-out charges or exclusions apply.
Boiler reliability: Warranty length doesn’t establish how reliable the appliance will be.
It’s also worth considering how long boilers typically last. A long warranty can cover a substantial part of an appliance’s expected working life, but it doesn’t guarantee the boiler will remain fault-free throughout that period.
Is an extended boiler warranty worth paying for?
It depends on the additional cost and protection offered.
If a modest upgrade provides several extra years of comprehensive parts-and-labour cover, it may be worthwhile.
However, paying considerably more for an extended warranty on a boiler with expensive servicing conditions or significant exclusions may offer less value.
Compare the total cost of qualifying for the extension with the benefits it provides.
Also consider whether the extra years are included in the installation quotation or require a separate payment.
For homeowners with an existing manufacturer warranty, separate boiler cover (Is Boiler Cover Worth It?) may duplicate some protection. It’s worth checking what’s already included before buying an additional policy.
Boiler warranty vs boiler cover: what’s the difference?
A manufacturer warranty generally protects against qualifying product defects under the manufacturer’s terms.
Boiler cover is a separate insurance or service agreement that may provide assistance with certain breakdowns, repairs or maintenance, depending on the policy.
Some boiler-cover plans include annual servicing, while others charge separately.
Neither arrangement automatically covers every heating-system problem.
For example, a manufacturer’s warranty may exclude a fault caused by dirty system water, while a separate boiler-cover policy may also exclude pre-existing faults or poor maintenance.
The best approach is to compare the actual terms, rather than assuming one form of protection always replaces the other.
What should you check before choosing a boiler warranty?
Before accepting a new-boiler quotation, make sure you understand the protection being offered.
| Question | Why it matters |
| What is the exact warranty period? | The advertised maximum may not apply |
| Is the cover for parts and labour? | Component-only protection may leave repair costs |
| Does the installer need accreditation? | Some extensions require an approved installer |
| Is an additional filter required? | Missing equipment may affect eligibility |
| Is there an extension fee? | The longest option may increase the upfront cost |
| When must registration be completed? | Missing deadlines can reduce cover |
| What servicing records are needed? | Poor documentation can complicate claims |
| Is the warranty transferable? | Important if you sell the property |
Ask for written confirmation of the selected warranty before installation and retain the final certificate afterwards.
Frequently asked questions
Which boiler brand offers an 18-year warranty?
ATAG currently advertises an optional eighteen-year manufacturer warranty on its domestic gas boilers, compared with twelve years as standard. The upgrade and ongoing coverage are subject to the manufacturer’s conditions.
Which boiler brands offer 12-year warranties?
Selected boilers from ATAG, Worcester Bosch, Ideal, Viessmann and Intergas offer twelve years or more of advertised cover, although the conditions vary considerably.
Do all boilers come with a ten-year warranty?
No. Warranty periods differ between manufacturers and individual models. Some boilers offer only a few years of standard cover, while others provide ten or twelve years subject to registration and maintenance conditions.
Does a boiler warranty include annual servicing?
Usually not. Annual servicing is commonly required to maintain the warranty, but homeowners generally pay for it separately unless their installation or service agreement says otherwise.
Can a boiler warranty transfer to a new homeowner?
Sometimes. Baxi and ATAG, for example, allow remaining warranty protection to transfer with the boiler, subject to the relevant terms and ongoing maintenance requirements. Check the manufacturer’s policy before buying or selling a property.
Accurate as of: 27 October 2026