The three tiers on our list
Five years on the budget pair — the Baxi/Main Eco Compact and Worcester Greenstar 1000 at £1,999. Seven years on the Baxi 600 at £2,199, which is what makes it the best warranty-per-pound we fit. Ten years on the Worcester Greenstar 4000 and 8000 and the Vaillant ecoTEC plus.
The condition every manufacturer shares
Manufacturers can refuse a claim if the system was not cleaned and correctly dosed at installation. This is the small print that catches people who bought on price alone. Every installation on this site includes the chemical cleanse and long-term inhibitor as standard — not as an optional extra — precisely so the warranty stands up.
Registered for you, not left to you
An unregistered warranty can quietly default to a shorter statutory period. We register yours at handover, in your name, and leave the paperwork with you — it is on the inclusions list for every job, not a favour.
Warranty length as a buying signal
A manufacturer putting ten years behind a boiler is telling you something about the boiler. It is also telling you how to choose: staying in the house for years, the longer-warranty models earn their extra cost across the term. Moving on soon, the five-year pair is the rational buy. There is no single best boiler — there is the right output for your radiator count and the right warranty for how long you plan to stay.