Boiler Warranty UK — What Is Covered, What Voids It, and How to Claim
Most new boilers come with 5-12 year manufacturer warranties. But the fine print contains conditions that void the warranty if not followed. This guide explains exactly what is covered, what voids cover, and how to make a claim.
Boiler Manufacturer Warranties in the UK
All major boiler manufacturers offer manufacturer warranties on new boilers in the UK. The warranty duration has increased significantly — it is now used as a marketing differentiator, with Worcester Bosch and Vaillant competing on 10-12 year warranties for premium models.
| Brand | Model Range | Standard Warranty | Extended (with registration) |
|---|---|---|---|
| Worcester Bosch | Greenstar 4000 | 2 years | Up to 10 years (with annual service) |
| Worcester Bosch | Greenstar 8000 | 2 years | Up to 12 years |
| Vaillant | ecoTEC plus | 2 years | Up to 10 years |
| Baxi | 800 Combi 2 | 2 years | 7 years |
| Ideal | Logic Max | 2 years | 10 years |
| Glow-worm | Energy | 2 years | 7 years |
Registration and ongoing conditions apply — see below.
What the Warranty Covers
Manufacturer warranties typically cover:
- Parts that fail due to manufacturing defect within the warranty period
- Labour costs for warranty repair (varies — some cover only parts)
- Replacement boiler if a fault cannot be repaired within a reasonable number of attempts
They do not cover:
- Normal wear and tear (e.g. pump brushes, seals that degrade over time)
- Damage caused by poor installation or system issues
- Damage caused by failure to maintain (no annual service)
- Damage caused by scale (in hard water areas — a major exclusion)
- Consequential loss (e.g. cost of temporary heating while boiler is repaired)
What Voids a Boiler Warranty
The conditions that most commonly void boiler warranties in the UK — and which are most often not followed by London landlords and homeowners:
- No annual service: All major manufacturers require annual servicing by a Gas Safe registered engineer. Records must be kept. Missed service = voided warranty from that point.
- No system inhibitor: Manufacturers require a corrosion inhibitor (Fernox F1, Sentinel X100) in the system at the correct concentration, tested at every service. An empty or diluted inhibitor is the most common warranty claim rejection reason.
- No scale reducer (in hard water areas): Worcester Bosch, Vaillant and others explicitly require a scale reducer or water softener on the cold feed in hard water areas (defined by calcium hardness >200mg/l — which covers all of London). Failure to fit one voids the warranty for heat exchanger failures.
- Non-registered installation: Some warranties are shortened if the boiler is not registered with the manufacturer within 30 days of installation. Registration is typically done by the installing engineer.
Frequently asked questions
Does a boiler warranty cover labour costs?
It depends on the manufacturer and warranty tier. Premium warranties (Worcester Bosch Greenstar 8000, Vaillant ecoTEC exclusive) typically include parts and labour. Standard warranties often cover parts only — you pay the engineer's call-out and labour. Check the specific warranty document for the boiler you purchased.
How do I make a warranty claim for my boiler?
Contact the manufacturer's warranty claims line (all have dedicated 0800 numbers). They will ask for: proof of purchase, registration confirmation, and annual service records. They will send an approved engineer. Do not use a non-approved engineer for the repair if you intend to make a warranty claim — using an unapproved engineer for warranty repairs can void the claim.
Does a boiler warranty transfer when a property is sold?
Most manufacturer warranties are property-based, not person-based — they transfer to a new owner. However, the new owner must maintain the annual service obligation and inhibitor/scale reducer requirements to keep the warranty valid. Check the warranty document and inform the buyer of the service history.
My boiler warranty claim was rejected — what can I do?
If a claim is rejected because annual service was not carried out, or inhibitor was not maintained, the rejection is likely valid under the warranty terms. If you believe the rejection is unjustified, escalate to the manufacturer's customer service director in writing. If still unresolved, the Consumer Rights Act 2015 applies to goods that are not of satisfactory quality — you may have a claim against the installer or retailer for goods that fail prematurely.