Boiler Warranties Explained: What's Covered and What Isn't

A boiler warranty can be one of your most valuable protections against unexpected repair costs — but only if you understand what it covers and what you need to do to keep it valid.

Standard warranty lengths

Most boiler manufacturers offer warranties of 2–10 years depending on the model and installation route:

BrandStandard WarrantyMaximumWorcester Bosch2 years12 years (accredited installer)Vaillant2 years7 years (registered installer)Ideal2 years10 years (registered installer)Baxi2 years10 years (registered installer)Viessmann2 years5 years

To access extended warranties, the boiler typically needs to be installed by an Accredited or Registered installer for that brand.

What's typically covered

Most boiler warranties cover manufacturing defects in parts and materials. This generally includes:

Heat exchanger failures

Control board faults

Gas valve failures

Sensor failures

Most internal component failures not caused by external factors

What's typically NOT covered

Understanding exclusions is just as important:

**Lack of annual servicing:** Most warranties require annual servicing by a Gas Safe engineer to remain valid. Skipping even one service can void the warranty.

**Incorrect installation:** Faults caused by poor installation (wrong gas pressure, incorrect flue, missing filter) are typically excluded.

**External damage:** Physical damage, flooding, or fire damage is not covered.

**Lime scale and sludge damage:** Damage caused by hard water scale or system sludge is often excluded. Fitting a magnetic filter is usually required.

**Normal wear and tear items:** Ignition electrodes, seals, and similar consumables are often excluded from longer warranties.

How to keep your warranty valid

1. **Annual servicing:** Book every year and keep records.

2. **Install a magnetic filter:** Most manufacturers now require this at installation.

3. **Use inhibitor:** Corrosion inhibitor in the system water is a standard requirement.

4. **Register the warranty:** Most manufacturers require online registration within 30 days of installation.

NBS Plumbing & Heating registers all warranties on your behalf and reminds you when your annual service is due — **07507 133204**.