Which Boiler Brand Should You Buy?
Worcester Bosch, Vaillant, Ideal and the rest: an installer's honest view of the brand question.
The forums overstate the gaps
The mainstream brands are closer in reliability than the arguments suggest. Warranty length, local parts availability and the quality of the installation move your outcome far more than the badge does.
What actually matters
A boiler sized correctly for the house, fitted to manufacturer spec, on a cleansed system with a magnetic filter, serviced annually. Do those four things and any mainstream brand will see out its warranty and beyond.
Our practice
We fit the brands whose parts sit on the merchant's shelf in your postcode, because a rare boiler with a two-day part wait is a worse product than a common one fixed by teatime, whatever the review score said.
What actually predicts reliability
Not the badge. Correct sizing, a clean system at installation, an annual service and decent water treatment predict boiler life far better than brand does. The most common cause of early failure we attend is a good boiler fitted to a dirty system, which pushes years of sludge through a new heat exchanger from day one.
Sizing: bigger is not better
An oversized combi short-cycles, firing and stopping repeatedly, which wears components and wastes gas. Size is calculated from heat loss and hot water demand, how many bathrooms, used how, not from the size of the house. A correctly sized 24kW unit will outperform and outlast a casually specified 35kW one.
Warranties and what voids them
Long warranties are genuinely valuable, and they almost all require an annual service recorded in the benchmark book plus, frequently, a system filter and inhibitor. A missed service is the most common reason a claim is refused. Read what the warranty requires of you before choosing between two brands on warranty length.
What the fault code is really telling you, what's safe to try, and when to stop.
Five checks that fix a surprising share of no-hot-water mornings for free.
Valve, spindle, tail or the panel itself, each one leaks differently, and only one of them means a new radiator.
A sealed system does not consume water. If you are topping up, it is going somewhere, and where matters.
Immersions, multipoints and wall heaters fail in predictable ways. What to check before replacing anything.