F-Gas Exam Categories Explained: Category I vs II vs III vs IV

Why Categories Exist

The F-Gas certification system is not one-size-fits-all. In Great Britain, RACHP personnel certification is still structured around four categories, each corresponding to a different scope of permitted activities. The category you need depends on the type of work you carry out and the size of systems you work on.

Choosing the right category is important. If you hold a lower category than your work requires, you are operating outside the law. Conversely, if you only perform limited tasks, you may not need to sit the full Category I exam. This guide breaks down each category so you can make an informed decision.

Category I: Full Scope

Category I is the highest level of F-Gas certification and grants the widest scope of permitted activities. If you hold a Category I certificate, you are qualified to carry out:

• Leak checking on all systems, regardless of charge size
• Recovery of F-gases from all systems
• Installation of F-gas equipment
• Maintenance and servicing of all F-gas systems
• Repair of systems containing F-gases
• Decommissioning of F-gas equipment

There are no restrictions on the size of the system or the quantity of refrigerant. Category I is the certificate that most professional HVAC and refrigeration engineers should aim for, as it covers every activity you are likely to encounter in the field.

Who Needs Category I?

• Refrigeration engineers who install and commission systems
• Air conditioning technicians working on split systems, VRF/VRV, and chillers
• Heat pump installers
• Service engineers responsible for full system maintenance
• Anyone who needs unrestricted access to work on F-gas equipment

Exam Requirements

For candidates taking the City & Guilds route, Category I maps to the current 2079-11 award. The online knowledge test is 40 multiple-choice questions in 80 minutes, and City & Guilds sets the pass mark at 24 marks. The wider qualification also includes practical assessment.

Category II: Limited Charge Size

Category II certification permits all the same activities as Category I, but with a critical restriction: it only applies to systems containing less than 3 kg of F-gas charge (or less than 6 kg for hermetically sealed systems that are labelled as such).

With a Category II certificate, you can:

• Leak check systems with less than 3 kg charge
• Recover refrigerant from systems with less than 3 kg charge
• Install systems with less than 3 kg charge
• Maintain and service systems with less than 3 kg charge
• Repair and decommission systems with less than 3 kg charge

Who Needs Category II?

• Technicians who exclusively work on small domestic or light commercial systems
• Engineers working only with small split systems or portable units
• Those who want a stepping stone before progressing to Category I

Availability Note

The scope above is still useful for understanding the category system, but City & Guilds marks the 2079-12 Category II route as no longer awarded. If you think Category II matches your work, check which awarding bodies still offer it before you plan your training.

Practical Considerations

While Category II covers a useful range of smaller equipment, many employers and clients prefer technicians with the full Category I qualification. The 3 kg charge limit can be restrictive in practice, as many commercial air conditioning systems and refrigeration units contain charges well above this threshold. If there is any chance your work will involve larger systems, Category I is the better investment.

Category III: Recovery Only (Small Systems)

Category III is a specialist certificate focused solely on the recovery of F-gases from systems containing less than 3 kg of charge (or less than 6 kg for labelled hermetically sealed systems).

With a Category III certificate, you can:

• Recover F-gases from small systems (under 3 kg)

You cannot install, maintain, service, repair, commission, or leak check systems under this category. It is a narrow, task-specific qualification.

Who Needs Category III?

• Waste management and recycling operatives who need to recover refrigerant from end-of-life equipment (old fridges, freezers, and small air conditioning units)
• Scrap metal processors handling WEEE (Waste Electrical and Electronic Equipment)
• Anyone whose sole involvement with F-gases is recovering them from small appliances prior to disposal

Exam Requirements

The Category III exam is shorter and covers fewer skill groups than Categories I and II. It focuses primarily on safe recovery procedures, equipment handling, environmental regulations, and personal safety.

Category IV: Leak Checking Only

Category IV is another specialist certificate, this time focused on leak checking only, provided you do not break into the refrigeration circuit. Unlike Category II and III, it is not primarily defined by a 3 kg charge threshold.

With a Category IV certificate, you can:

• Carry out leak checks without opening or otherwise breaking into the refrigeration circuit

You cannot install, recover, maintain, service, repair, or decommission systems under this category.

Who Needs Category IV?

• Building maintenance staff who are responsible for routine leak checks on large commercial HVAC systems but do not carry out any refrigerant handling
• Facilities managers or maintenance staff who need to perform routine leak inspections only
• Compliance staff who physically carry out scheduled leak checks but do not service the plant

Exam Requirements

The Category IV exam is focused on leak detection methods (both direct and indirect), leak-check frequencies, record-keeping requirements, and the legal limits of what you may do without breaking into the circuit.

Comparison Summary

Feature	Category I	Category II	Category III	Category IV
Leak checking	All systems	< 3 kg	No	Yes, without breaking into the circuit
Recovery	All systems	< 3 kg	< 3 kg only	No
Installation	All systems	< 3 kg	No	No
Maintenance/Service	All systems	< 3 kg	No	No
Charge size limit	None	< 3 kg	< 3 kg	Activity-limited rather than charge-limited
Exam difficulty	Highest	Moderate	Lower	Lower

Which Category Should You Choose?

For most HVAC and refrigeration professionals, Category I is the recommended choice. It provides full, unrestricted access to all F-gas activities and is the qualification that employers and clients expect. The exam is more demanding, but with proper preparation it is entirely achievable.

If you are certain your work will only ever involve small systems under 3 kg, Category II may suffice. Categories III and IV are appropriate only for those with very specific, limited roles that do not involve general refrigerant handling or system installation.

Whichever category you pursue, make sure you are matching the certificate to the actual work you carry out. Also note that a UK F-Gas certificate is not automatically valid in the EU, so cross-border work may require separate recognition.