CO inspection: checklist and what needs to be on your work order

A CO inspection is not just a measurement — it is a fixed inspection protocol that you must be able to demonstrate. For refrigeration and installation companies working under the Gasketelwet, what matters is not only what you measure, but also whether that is traceably recorded: which technician, which checklist, which result, and on which work order. This article works through the checklist and shows what needs to end up in your records.

What is checked during a CO inspection?

A CO inspection of a gas combustion appliance — usually a central heating boiler — revolves around four areas of attention:

• CO concentration, measured in ppm (parts per million), both unloaded and under load.
• Combustion air supply — does the appliance get enough clean air to burn completely?
• Flue gas discharge — is the flue gas discharged safely and completely, without leaking into the installation space?
• Installation space — is the room in which the appliance is located suitable (ventilation, free passage, no obstructions)?

These are not standalone checks: a fine CO value in a poorly ventilated installation space is still a risk, because conditions can deteriorate after the inspection — a closed-off ventilation grille, boxes blocking the air supply. A proper CO inspection therefore always works through the entire checklist, not just the measurement.

CO values: unloaded and under load

Two measurements, two situations:

• CO unloaded — the CO concentration during normal, stable operation of the appliance.
• CO under load — the CO concentration while the appliance is put under extra load (for example by temporarily restricting the air supply), to see how the appliance behaves under less ideal conditions.

Both values belong in the inspection report, not just the more favourable of the two. An appliance that measures fine unloaded but shows a sharp rise under load deserves a more critical look than the unloaded measurement alone would suggest.

Result: approved, conditional or rejected

A CO inspection ends in one of three outcomes:

• Approved — all checklist points and CO values are in order.
• Conditionally approved — there is a point of attention that needs to be resolved in the short term, but the appliance is not immediately unsafe.
• Rejected — there is a risk that requires immediate action, for example a CO value that is too high or a blocked flue gas discharge.

With "conditionally approved", always record which point is outstanding and by which date it must be resolved — otherwise that conditionality can no longer be traced at the next audit.

How often is a CO inspection needed?

The frequency depends on the maintenance contract and the type of appliance — in practice often linked to the annual maintenance moment of the central heating boiler. Certifying bodies and manufacturers can set additional requirements for the frequency. Include this explicitly in your maintenance contract and check the current requirement with your certifying body.

What needs to be on the work order?

A correct work order protects your CO certification; an incomplete work order undermines it. At a minimum, make sure you have:

• Which technician carried out the inspection, with a valid CO-person certificate at the time of the inspection.
• Which installation it concerns — make, type, location.
• The measured CO values (unloaded and under load) and the result of the checklist.
• The final outcome — approved, conditionally approved or rejected — with any follow-up action and deadline.
• Both signatures, just as with any other work order (see what needs to be on a work order?).

That last point is exactly where it often goes wrong: a CO inspection kept separately from the work order in a separate Excel file or on paper is difficult to link to the correct file at an audit — and that is exactly the kind of gap an auditor picks out.

How Koldwerk records the CO inspection

The CO inspections module can be started from the installation or directly from an open work order. You work through the fixed checklist, enter the CO values, and the result (approved, conditionally approved, rejected) is automatically added to the chronological inspection history of that installation, with a downloadable inspection report. Because the inspection only starts with a technician who holds a valid CO-person certificate, no inspection can go out the door that would not hold up at an audit.

Further reading

• What is the Gasketelwet? — the legal framework
• CO-person certificate: what you need to know
• What needs to be on a work order?
• F-gas logbook: what needs to be in it? — the equivalent requirement for refrigerant installations

Disclaimer: the checklist in this article is a practice-oriented summary, not the literal standard text of BRL 6000-25 or BRL K25000. If in doubt, have the checklist assessed by an expert on that scheme before using it as formal compliance evidence — consult Kiwa (opent in nieuw tabblad) or InstallQ (opent in nieuw tabblad) for the official requirements. Not legal advice.