Boiler maintenance: why and how often?
What a service actually covers, what it costs, and why it's best done before winter.
During a service the engineer cleans and checks the burner control, the heat exchanger, the water pressure and the flue, and measures the combustion (CO/CO₂). Minor issues — a fouled burner, dropping pressure, a worn gasket — are fixed straight away before they grow into a mid-winter breakdown.
A service costs € 80 to € 160, depending on the boiler type and whether you book a one-off visit or take out a multi-year contract. A contract is often slightly cheaper per visit and gives priority for breakdowns; a one-off visit makes more sense if you've just moved in or are unsure about replacement.
The advice is once a year, or at least every two years. Ideally have it done in October or November: the boiler is then ready for the heating season and you avoid the queue when the first cold weekend floods the breakdown lines.
One more reason not to postpone: with many brands periodic maintenance is required to keep the manufacturer's warranty valid. Keep the invoice and service report — it saves arguments if something fails within the warranty period.