Manufacturer's Warranty and Ten-Year Liability on a New Boiler in Brussels: What's Actually Covered

When you invest in a new boiler, you often hear the word "warranty" without always knowing exactly what it means. Manufacturer's warranty, ten-year liability (garantie décennale), installer's warranty: these terms are easily mixed up in the minds of Brussels homeowners, and that's understandable. Each one covers different things, for different lengths of time, under different conditions. Let's clarify things, so you know exactly what you can rely on if something goes wrong after installation.

Manufacturer's warranty: what it actually covers

The manufacturer's warranty is the one that comes with the appliance itself. It is issued by the brand (Vaillant, Viessmann, Bulex, Daikin, and many others) and covers manufacturing defects in the equipment: a heat exchanger that leaks due to a design flaw, an electronic board that was faulty from the start, a component that doesn't meet the stated specifications.

Duration and scope

The length of this warranty varies depending on the manufacturer, the model, and sometimes even on whether the appliance was registered online after installation. Some brands distinguish between the "parts" warranty and the "heat exchanger" warranty (the main exchanger), with the latter generally lasting longer. It's essential to read the instructions and the warranty certificate supplied with your boiler carefully, rather than relying on durations you've "heard somewhere", as these change regularly from one manufacturer to another and from one range to another.

In any case, this warranty only covers the equipment. It does not cover the labour needed to remove and refit the appliance, unless explicitly stated otherwise in the terms. This is something many homeowners discover too late: the manufacturer replaces the faulty part free of charge, but the call-out and the heating engineer's working time are often still chargeable, unless a maintenance contract or a commercial warranty extension has been taken out.

What it doesn't cover

The manufacturer's warranty never covers an installation error, incorrect sizing, a setting defect, or a breakdown caused by lack of maintenance. Nor does it cover normal wear of consumable parts (seals, ignition electrodes, for example), or damage linked to unstable electricity supply, a frozen system, or work carried out by someone who isn't qualified. If the manufacturer finds that the boiler has been poorly maintained or that non-approved parts have been used, they are entitled to refuse cover, even if the appliance is still within the theoretical warranty period.

Installer liability and ten-year liability (garantie décennale)

This is where many people get confused: between the manufacturer's warranty and the liability of the company that carried out the installation. These are two legally distinct matters.

What ten-year liability actually covers

Under Belgian law, ten-year liability (garantie décennale) concerns the liability of builders and installers for serious defects that compromise the stability or intended use of a structure, and which were not apparent at the time the work was accepted. For a boiler, this typically applies to situations where the installation itself has a serious structural defect: a poorly made connection that eventually causes significant damage, a flue system that doesn't comply and puts the building's safety at risk, an installation error that renders the work unfit for its purpose.

This liability therefore does not cover the replacement of a faulty component in the commercial sense, but rather the consequences of a hidden defect linked to the installation work. It's an important protection, but it applies to more serious and rarer cases than a simple component failure.

Difference from the manufacturer's warranty

In short: the manufacturer's warranty protects the equipment against manufacturing defects, while installer liability covers the quality and compliance of the installation work. A reliable installer also remains liable, for a shorter period, for obvious defects found shortly after commissioning (sometimes referred to as the guarantee of proper completion). This is why it's important to receive a proper commissioning report and to carefully keep the detailed installation invoice: these documents are your evidence in the event of a dispute.

The conditions for not losing your warranty

A warranty, whether from the manufacturer or linked to the installation, is never granted unconditionally. Several requirements must be met for it to remain valid throughout its term.

Installation by an approved professional

Most manufacturers require the installation to be carried out by an installer who is approved or certified for their brand, and for commissioning to be done properly, with settings suited to the type of fuel and the configuration of the building. An installation carried out by someone unqualified, even if it works initially, can be enough to invalidate the warranty if a problem arises later.

Regular maintenance and the boiler logbook

This is probably the most commonly overlooked condition, and the one most often cited by manufacturers to refuse cover. Almost all commercial warranties require annual maintenance carried out by a professional, with written proof: an invoice, a maintenance report, or a completed boiler logbook. Without this evidence, it becomes very difficult to assert your rights in the event of a breakdown, even if it is clearly due to a manufacturing defect.

In Brussels, this maintenance is not just a commercial recommendation: regional regulations require a mandatory periodic inspection of heating systems, with a frequency that differs depending on whether the boiler runs on gas or heating oil and on the appliance's power rating. We recommend checking the exact frequency that applies to your system on the Brussels Environment website, as these obligations are governed by law and compliance with them affects your safety, the validity of your home insurance, and the continuation of your manufacturer's warranty.

Beyond the regulatory aspect, regular maintenance also helps detect early warning signs of a breakdown or combustion fault, and ensures the appliance poses no carbon monoxide risk. At each visit, an approved heating engineer checks, among other things, the tightness of connections, the flue system, and the quality of combustion.

Original parts and unauthorised repairs

Manufacturers generally require that only original or approved parts be used for repairs. Calling on a handyman or attempting a repair yourself, even for a fault that seems minor, can be enough to void the warranty on the entire appliance, not just on the part concerned. This is a strict rule, but a logical one: the manufacturer cannot guarantee an appliance whose maintenance and repair history they no longer control.

What to do if your boiler breaks down during the warranty period

If your boiler breaks down while still under warranty, the first thing to do is gather your documents: the purchase and installation invoice, the manufacturer's warranty certificate, and proof of maintenance carried out. Then contact your installer, who is usually the first point of contact for submitting a claim to the manufacturer. They will be able to determine whether the breakdown is due to a manufacturing defect covered by the commercial warranty, an installation issue that falls under their own liability, or normal wear and tear that remains your responsibility.

Don't delay reporting the problem: most warranties require the defect to be reported within a reasonable time after it is noticed, and a poorly handled emergency repair can sometimes complicate the claim process.

What DPS Chauffagiste guarantees you

At DPS Chauffagiste, we install gas and heating-oil boilers as well as heat pumps as an approved installer, which allows our customers to fully benefit from the manufacturer's warranties offered by the major brands we fit. We always provide a detailed commissioning report and a clear invoice, two documents that are essential should a warranty claim ever become necessary.

We also offer annual maintenance contracts that not only help you meet your legal obligations in Brussels, but also provide the written record required by manufacturers to keep your appliance's warranty active throughout its full term. In our view, this is the best way to protect your investment in the long run: an installation carried out properly, followed by regular, documented maintenance.