CMDDA1 Course – Carbon Monoxide & Combustion Gas Analysis

Course overview

Delivered over a single day at our Paisley training academy, this course assesses your ability to measure ambient levels of carbon monoxide (CO) and carbon dioxide (CO₂) inside a home, and to run combustion checks on domestic gas appliances using a portable electronic flue gas analyser. It is built for working engineers who attend genuine CO incidents and need formal sign-off to act on what their instruments tell them.

The assessment follows the guidance set out in BS 7967 Parts 1 to 4. It deals strictly with domestic premises and appliances — commercial work and the formal reporting of incidents under RIDDOR fall outside its scope and are covered by separate qualifications.

Course overview

You’ll be trained and assessed across the following:

• Taking accurate ambient CO and CO₂ readings within a domestic dwelling
• Using a portable electronic combustion analyser correctly and safely
• Carrying out combustion performance checks on domestic gas appliances
• Responding to a reported CO alarm activation in a methodical way
• Investigating reports of fumes, smells or visible spillage of combustion products
• Identifying which appliance is producing unsafe products of combustion
• Interpreting readings against recognised action levels and deciding the right next steps

Why this module matters

Carbon monoxide gives no warning of its own — no colour, no smell, no taste — yet it remains a serious cause of preventable harm in UK homes every winter. An engineer who can confidently quantify CO in a property and pinpoint its source is often the person standing between a faulty appliance and a tragedy. CMDDA1 turns that responsibility into a measured, repeatable procedure.

Entry requirements

CMDDA1 builds on core gas safety competence, so you’ll need to hold a current qualification before you can sit it. To enrol you must have a valid:

• Core Domestic Gas Safety (CCN1), or
• Core LPG Gas Safety (CCLP1), or
• an accepted equivalent NVQ or QCF gas qualification

You should also be comfortable using a portable electronic combustion analyser, as the assessment is hands-on. If you’re due a wider ACS renewal at the same time, mention it when booking and we’ll line the modules up across your visit.

Initial — for engineers adding CMDDA1 to their certification for the first time, or whose previous certificate has lapsed by more than 12 months.

Re-assessment — for engineers renewing a current CMDDA1. You can sit your re-assessment up to six months before your expiry date without losing any time on your renewed certificate.