Brussels' regional regulations have required boilers to have regular maintenance:

• every 2 years for gas boilers
• every year for oil boilers

This must be carried out by an approved boiler engineer. In addition to being mandatory, this maintenance is very useful as it helps you make energy savings and keeps you safe, in particular from carbon monoxide poisoning.

As boiler maintenance is a mystery to us mere mortals, we asked an engineer to describe the process for us, step by step.

1. Checking the general condition of the boiler.

To start with, the engineer takes 4 mandatory measurements:

1. efficiency
2. chimney temperature
3. CO2
4. CO

They will also take other useful measurements. The aim is to get an initial indication of the condition of the boiler and how it is working.

2. A thorough clean

Having checked these things, the engineer will then thoroughly clean any residue and dust that the boiler could suck in.

3. Time for a detailed check

Next the engineer ensures the parts are working properly, thus enabling the boiler to function automatically and guaranteeing your safety. They will also check the minimum air and gas input.

If you have a condensing boiler, the draining system for condensates will also be checked, as will the condition of the heat exchanger in wall-mounted units.

If required, the engineer will replace any damaged parts, and finally sweep the chimney.

4. Final adjustments and checks

To ensure your boiler is in perfect working order, the engineer will take the initial measurements again. If the results do not fall within the legal limits, they will make some adjustments.

5. Provision of the certificate

Finally, the engineer will give you a certificate declaring whether or not the boiler complies with the PEB (building energy efficiency) requirements.

This document is required for compliance with the region's regulations, and also for insurance purposes. If the boiler is not in compliance, you have 5 months to ensure that it is.