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LCL Awards CMDDA1 Domestic CO/CO2 Atmosphere & Appliance Testing (Natural Gas) Course
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LCL Awards CMDDA1 Domestic CO/CO2 Atmosphere & Appliance Testing (Natural Gas) Course

2 days
Level 3 Certificate

The CMDDA1 (Domestic CO/CO₂ Atmosphere & Appliance Testing) qualification enables gas engineers to safely and competently assess carbon monoxide (CO) and carbon dioxide (CO₂) levels in domestic premises using portable electronic analysers, and to undertake combustion testing where fumes, smells or combustion product concerns are reported.

It is essential for operatives responding to CO alarm activations or suspected leakage of combustion products in domestic settings

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LCL Awards CMDDA1 Domestic CO/CO2 Atmosphere & Appliance Testing (Natural Gas) Course

Why Take the CMDDA1 Qualification?

The LCL Awards CMDDA1 CO/CO₂ Atmosphere & Appliance Testing qualification aligns with industry-recognised standards and ACS criteria for safe domestic gas work. It demonstrates your capability to accurately conduct carbon monoxide and carbon dioxide testing using portable combustion analysers, ensuring the safety of occupants and compliance with UK gas safety guidance.

Training and assessment provided by PASS means you’ll benefit from expert assessors with real-world industry experience, dedicated training facilities, and tailored support that helps you prepare confidently and perform effectively in assessment conditions.

LCL Awards CMDDA1 Domestic CO/CO2 Atmosphere & Appliance Testing (Natural Gas) Course
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Overview
What Will I Learn On This Course?
Course Content

What does the CO/CO₂ Atmosphere & Appliance Testing course cover?

This assessment tests your ability to safely carry out CO and CO₂ atmosphere testing and combustion performance analysis in domestic dwellings following indications of fumes, smells or activated CO alarms.

Topics & Syllabus

The CMDDA1 syllabus is designed to assess real-world investigative and testing competence using industry-standard procedures and equipment and includes:

  • Conducting ambient CO and CO₂ atmospheric testing
  • Identifying combustion product leakage and potential causes
  • Using portable electronic combustion analysers
  • Interpreting the analyser results to assess safety
  • Following BS EN 7967 Part 1–4 guidance and HSE recommendations
  • Reporting outcomes and documenting findings
Learning Outcomes

What skills will I gain?

Completing CMDDA1 equips you with the skills to assess and interpret gas analyser readings and investigate potential combustion product issues in domestic properties.

Skills gained include:

  • Proper use of electronic combustion analysers
  • Recognising signs of unsafe combustion and atmospheric contamination
  • Understanding relevant safety standards and guidance
  • Reporting and documenting investigations effectively
  • Differentiating between safe and unsafe gas appliance conditions
  • Interpret analyser readings and assess appliance safety

Related Courses

Further expand your domestic gas competence with the MET1 Domestic Meters up to U16 (Natural Gas) Course or the CENWAT1 Domestic Central Heating Boilers & Water Heaters (Natural Gas) Course.

Assessment

Assessments

Assessment combines written and practical evaluations to confirm competence and compliance.

Assessment format:

  • Open-book written assessments using approved reference materials
  • Multiple-choice and true/false questions
  • Practical demonstration of testing procedures and report completion
  • Live workshop activities to verify correct appliance and atmosphere testing techniques
Prerequisites

Entry Requirements

CMDDA1 is suitable for experienced gas engineers who need Initial Assessment or Re-Assessment in CO/CO₂ testing as part of their domestic gas work competence.

Typical candidates include:

  • Gas engineers responding to CO alarm call-outs
  • Operatives needing domestic CO/CO₂ atmospheric testing certification
  • Technicians requiring re-assessment to extend or renew CMDDA1 competence
  • Personnel regularly performing combustion analysis in dwellings

Before enrolling, candidates must have:

  • Valid gas safety qualifications (ACS core modules recommended)
  • Basic knowledge of gas appliances and installation procedures
What’s Included

What should I expect from the booking?

Our CMDDA1 course package includes:

  • Full training and assessment by qualified instructors
  • All necessary course materials and testing equipment access
  • Lunch and refreshments throughout the training day (tea, coffee, and juice)
  • Certification and course entry fees
Got a Question? We’ve Got Answers
Frequently Asked Questions
What is the CMDDA1 qualification for?

It certifies your ability to safely test for carbon monoxide and carbon dioxide in gas appliance atmospheres, essential for ensuring compliance and safety.

Who should take this course?

Gas engineers, heating engineers, and technical professionals working with gas-fired appliances requiring combustion gas testing.

Do I need previous gas qualifications?

Yes, a core ACS qualification or equivalent is recommended before taking CMDDA1.

Is there a refresher available?

Yes, reassessment courses are offered to maintain your CMDDA1 certification and update your knowledge.

What kind of equipment will I use?

You will use calibrated combustion gas analysers and atmosphere testing devices as part of the practical training.

Do I need an analyser to take this course?
You don’t need to bring your own analyser; practical assessment uses approved portable combustion analysers provided during assessment.
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