BRL 6000-25 vs BRL K25000 vs BRL SI-6025 (CO-Keur): the three routes compared

Since 1 April 2023, maintenance, repair, installation and commissioning of gas-fired combustion appliances may only be carried out by companies with a valid CO competence certificate. But "a CO certificate" is not a single, unambiguous thing: there are three recognised assessment guidelines (BRLs) through which you can obtain that certificate, each with its own scheme manager, its own scope and a different kind of track. Which of the three fits your company best depends on your company size, the kind of work you do and how much guidance you need.

This article sets the three routes side by side. For the cost of a CO inspection itself, see what a CO inspection costs; for the basics of the law itself, see what is the Gasketelwet.

The three routes at a glance

• BRL 6000-25 — the assessment guideline from scheme manager InstallQ. Certification is possible via multiple certifying bodies (including Kiwa, Normec, Bureau Veritas and Dekra). The guideline has two scope areas: scope area 1 for central heating appliances with individual flue gas discharge and air supply, scope area 2 for collective air supply and flue gas discharge provisions (CLV systems). Traditionally the most common route, including for larger installation companies.
• BRL K25000 — Kiwa's own guideline, developed as a more compact alternative alongside BRL 6000-25. It has five scope areas: installing, repairing, maintaining and commissioning gas-fired combustion appliances (scope areas 1 through 4), plus a separate scope area 5 for work on collective combustion air and flue gas discharge provisions (CLV) — you always apply for that scope area in addition to scope area 1, 2 and/or 3. Kiwa explicitly positions this route as suitable for smaller installation companies, among other things because part of the audit can be carried out remotely: Kiwa then monitors digitally and assesses work on a sample basis, instead of solely through physical site visits.
• BRL SI-6025 — the guideline behind CO-Keur, with SKG-IKOB as scheme manager. CO-Keur is a cooperative that guides the certification track for (often smaller and sole-trader) companies and does not issue certificates itself — actual certification runs via a certifying body. Important distinction: work on CLV systems is explicitly NOT covered by this BRL. Anyone who also services collective systems is therefore not compliant for that part of the work with SI-6025 alone.

Scope: the CLV distinction is the most important selection criterion

If you work exclusively on central heating boilers, combi boilers and gas water heaters with an individual flue gas discharge for residential or small business customers, all three routes cover that basic work. As soon as you also work on CLV systems (collective air supply and flue gas discharge, such as at apartment complexes), the distinction becomes sharp:

• BRL 6000-25 covers CLV work via the separate scope area 2 — you do need to certify specifically for that, in addition to scope area 1.
• BRL K25000 covers CLV work via the separate scope area 5, which you always apply for in addition to scope area 1, 2 and/or 3.
• BRL SI-6025 does not cover CLV work at all. If you do this work anyway, a different route is necessary.

So check your own order book first before choosing a route: a wrong choice means you will still have to arrange a second certification for part of your work.

Target audience and company size

• BRL 6000-25 is offered by multiple certifying bodies and is historically the route also used by larger and mixed installation companies.
• BRL K25000 is explicitly positioned by Kiwa as attractive for smaller installation companies, for whom an extensive certification track weighs disproportionately heavily on their operations.
• BRL SI-6025 via CO-Keur is explicitly aimed at smaller companies and sole traders who prefer to outsource the administrative hassle around certification to the cooperative.

The smaller and more specialised your company (particularly without CLV work), the sooner K25000 or SI-6025 come into the picture. If you work broadly, in a mixed way and/or with CLV installations, BRL 6000-25 is the more obvious choice.

Audit format: on-site versus (partly) remote

A concrete operational difference is the way the certifying body checks your work. BRL K25000 offers the explicit advantage that part of the assessment can take place remotely, with sample-based checking of work carried out. With BRL 6000-25, the assessment generally runs via the regular track of the chosen certifying body, including physical assessments. For SI-6025/CO-Keur, a large part of the accountability runs through an app in which you submit checklists and documentation per job carried out; the exact audit frequency and format is determined by the certifying body that CO-Keur works with.

Costs and track structure — briefly, with a reference

The three routes also differ in how the costs are structured: with BRL 6000-25 you pay, among other things, a licence fee to InstallQ plus the rate of your chosen certifying body; BRL K25000 as a guideline can be downloaded free of charge from Kiwa, with the certification costs on top; with CO-Keur/SI-6025 you typically pay a limited annual contribution to the scheme manager plus a fee per checklist completed. Exact amounts and lead times differ per certifying body and per company situation — a full cost overview with amounts is in what a CO inspection costs.

A personal certificate remains necessary, regardless of the route

Whichever of the three BRLs your company chooses for the process certificate: your technicians additionally always need their own CO competence certificate in order to be allowed to carry out the work. See CO-person certificate for exactly what that certificate covers, and CO inspection: checklist and work order for what needs to be recorded per inspection carried out. The distinction between a regular CO alarm check and an official CO inspection is explained in CO alarm check vs official CO inspection.

Can you switch between routes?

The sources consulted for this article do not go into detail on the exact procedure and costs of switching between BRL 6000-25, K25000 and SI-6025 partway through a certification cycle. So don't take this as settled: if in doubt, ask the scheme manager directly (InstallQ, Kiwa or SKG-IKOB/CO-Keur) what switching would cost in your situation and how long it takes, especially if you have a running certification contract (with BRL 6000-25, for example, this involves a multi-year agreement with the certifying body).

In short: how do you choose?

• Do you (also) do CLV work? Then SI-6025 alone is ruled out and you need to go with BRL 6000-25 (scope area 2) or K25000 (scope area 5, in addition to 1, 2 and/or 3).
• Are you a small, specialised company without CLV work, and do you want a compact track with (partly) remote assessment? K25000 is then worth considering.
• Do you want to largely outsource the administrative burden of certification, and do you mainly work on individual appliances? SI-6025 via CO-Keur is positioned for that.
• Are you a larger or mixed company, or do you want to be able to choose from multiple certifying bodies? Then BRL 6000-25 is the most proven route.

In all cases, have the scheme manager or certifying body confirm which route fits your exact work before you sign a contract — a wrong choice costs you time and money to fix later.