PRACTICAL GUIDE · UPDATED 2026-10-30
Boiler brands: compare the exact model, installer and warranty
Worcester Bosch, Vaillant, Viessmann, Ideal and Baxi are useful starting points—not a universal best-brand ranking.
| Manufacturer | What to check in the quoted offer |
|---|---|
| Worcester Bosch | The model’s guarantee terms and any qualifying installation package. |
| Vaillant | The domestic boiler guarantee terms, registration and any qualifying conditions. |
| Viessmann | The product warranty for the specific model and any extension conditions. |
| Ideal Heating | Registration instructions and the warranty terms for the model/package. |
| Baxi | How the warranty is registered, maintained and evidenced. |
Ask for more than a brand name. Compare the exact model and output, suitability for the home, compatible controls, complete installation scope, local servicing options and the manufacturer’s written warranty. A good design and installation matter alongside the equipment.
The manufacturers below publish their own warranty or guarantee conditions. Cover can depend on the model, registration, installation, servicing and any qualifying accessories or installer scheme. Do not assume the longest advertised term applies to your quote. Ask for the applicable document and confirmation of who registers the boiler.
Ask the installer: Why this model rather than another? What minimum heating output and hot-water delivery fit this home? Are controls, system cleaning, filter, flue work and commissioning included? Which faults or system components are excluded from the manufacturer’s cover? Who handles an installation defect separately from a product fault?
Keep the invoice, commissioning record, registration confirmation and annual service records. This is an independent question guide; the directory is not endorsed by these manufacturers and has not produced comparative reliability test results.
Your checklist
- Compare model numbers, complete prices and scope—not brand slogans.
- Request the exact warranty document before ordering.
- Ask about servicing cost, local support and replacement parts.
- Check independent model-specific evidence if reliability claims influence your decision.
Sources & further reading
- Worcester Bosch: Guarantee terms ↗
- Vaillant: Domestic boiler guarantee ↗
- Viessmann: Product warranties ↗
- Ideal Heating: Warranty registration ↗
- Baxi: Registering and maintaining warranty ↗
General information, not a property assessment, booking or assurance about a listed business. Dates indicate content updates; they are not invented publication dates.