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Maintenance · Oil boiler

Oil boiler servicing

Every year, in Brussels and in Flanders. An oil boiler fouls faster: burner, nozzle, filter and heat exchanger cleaned, flue-gas analysis with smoke index, official certificate.

Schedule my maintenance+32 15 62 70 80

  • 1,100+ customers serviced in 2 years
  • Certified gas and oil technicians
  • Official certificate provided

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What the law says

Brussels

Inspection every year by a certified technician (L). An existing oil boiler may keep running if inspected; installing a new one is banned since 01/06/2025.

Flanders

From 20 kW: every year, by a certified technician. The certificate lands in your Woningpas.

Thinking ahead

Is your oil boiler over 15 years old? We tell you frankly what is best, and what a heat pump or a hybrid would change.

Sources: Brussels Environment (19/01/2025), vlaanderen.be (read on 09/11/2026), Regulation (EU) 2024/573 on fluorinated gases.

What we check at each maintenance

The points of the sheet our technicians fill in at every visit, one by one.

Appliance servicing

  • General condition checked: cleanliness, tightness, wear, operation
  • Casing and electronics dusted
  • Burner cleaned: fan, combustion head, flame detector
  • Nozzle checked
  • Oil filter cleaned
  • Electrodes cleaned and set
  • Pump pressure checked and set
  • Heat exchanger cleaned
  • Condensate drain checked, siphon cleaned and filled
  • Burner set to the manufacturer's values

Flue and air

  • Flue checked and cleaned, or the sweep's certificate seen
  • Combustion air duct checked (room-sealed appliance)

Hydraulics and controls

  • Circulator works
  • Thermostat talks to the boiler
  • Valves and air vents work, no leak

Safety

  • Oil supply line and its valve tight, no leak
  • Measuring ports sealed again
  • Safety devices

The measurement

With the analyser, not by eye.

  • Combustion analysed before and after the work
  • CO, efficiency, flue gas temperature and smoke index
  • Compared with the legal limits of your region
  • The analyser's report kept as proof
  • Ambient CO measured on arrival and in front of the appliance

One-off service or maintenance contract

Two ways to have your appliance serviced: on request, or without giving it another thought.

One-off service

You call us when the due date nears, we schedule the visit, you pay for the service.

  • The same full service and the certificate
  • No commitment

Maintenance contract

We remind you before the due date and schedule the visit for you, at the pace of the chosen plan.

  • Reminder and scheduled visit
  • Fixed price per appliance, known in advance
  • History and certificates in your customer area

Why service

19

deaths a year in Belgium

Carbon monoxide is the first cause of fatal accidental poisoning. In Brussels, 2 to 3 people are poisoned every week, mostly by poorly maintained heaters and water heaters.

Poison Centre, 2018 to 2023 average; be.brussels, 15/10/2025

+5 %

more consumption

A poorly maintained boiler uses about 5% more: a well-tuned burner shows straight on the bill.

Flemish Energy and Climate Agency

2 years

of legal warranty, without proof of servicing

Without proof of servicing, the warranty often stops there. Vaillant grants its 3 extra years only to a serviced appliance, Viessmann asks for a maintenance contract.

Vaillant (20/10/2026) and Viessmann warranty terms

Frequently asked questions

Burning oil fouls the burner and the heat exchanger more. The law requires it every year, in Brussels and in Flanders.

At every service we check that the oil supply line and its valve are tight. The tank itself is not part of the boiler service.

Usually the occupant. In Brussels, the tenant arranges the inspection unless the lease names the owner or the property manager. In Flanders, the user is responsible and gives the owner a copy of the certificates.

That is no longer a service: see our page Urgent repair.

Let us schedule your next service

Tell us your appliance and your municipality: we suggest a date.

Schedule my maintenance+32 15 62 70 80