Last updated · Researched from official sources · By Studyforge Labs
The City & Guilds 2079 Level 2 Award in F Gas and ODS Regulations is the qualification that lets refrigeration, air conditioning and heat pump engineers in Great Britain legally handle fluorinated gases (F gas) in stationary equipment. Each category is passed with a closed-book online multiple-choice test plus a practical assessment, graded pass or fail. Category I, which covers all activities, uses a 40-question, 80-minute test with a pass mark of 24.
City & Guilds 2079 F-Gas key facts
| Key fact | Details |
|---|---|
| Full title | City & Guilds Level 2 Award in F Gas and ODS Regulations (2079), a vocational qualification at Level 2. |
| Categories currently awarded | Category I (2079-11), Category III (2079-13) and Category IV (2079-14). City & Guilds’ handbook states that Category II (2079-12) is no longer awarded. |
| Assessment | One online multiple-choice knowledge test and one practical assessment for each category. Both must be passed, and the result is pass or fail. |
| Category I test | 40 questions in 80 minutes, pass mark 24. |
| Category III test | 12 questions in 25 minutes, pass mark 8. |
| Category IV test | 16 questions in 35 minutes, pass mark 10. |
| Guided learning hours | 30 for Category I and 20 for Categories III and IV. |
| Entry requirements | No formal eligibility rules, but the qualification is approved for learners aged 16 and over and is aimed at people with some practical experience in the sector. |
| Awarding body fee | City & Guilds currently lists £86.40 for Category I and £94.70 each for Categories III and IV. Training centres set their own course prices, so check with your centre. |
Practise with F-Gas Prep (C&G 2079)
F-Gas Prep (C&G 2079) offers 2,000+ original questions, realistic timed mock exams, flashcards with spaced repetition and a readiness dashboard to help you prepare for the 2079 knowledge tests.
What is the F-Gas qualification and who needs it?
F gases are fluorinated greenhouse gases, mainly HFC refrigerants, used in refrigeration, air conditioning and heat pump (RACHP) systems. Government guidance says that anyone who works on equipment containing F gas needs their own qualification, even when they are employed by someone else. City & Guilds is one of the bodies gov.uk lists as an accepted provider of RACHP qualifications, alongside BESA and LCL Awards.
The 2079 award also covers ozone-depleting substances (ODS), such as older CFC and HCFC refrigerants.
F-Gas categories explained
Gov.uk describes four categories for stationary RACHP equipment:
| Topic | Details |
|---|---|
| Category I | Every RACHP activity, including installation, servicing, maintenance, leak checking and refrigerant recovery, with no charge-size limit. |
| Category II | Installation, maintenance, servicing and recovery on systems holding under 3 kg of F gas (under 6 kg if hermetically sealed). City & Guilds no longer awards its own Category II, so most engineers take Category I. |
| Category III | Refrigerant recovery only, from systems below the same 3 kg (or 6 kg hermetic) limits. |
| Category IV | Leak checking only, where the refrigeration circuit is not broken into. |
Personal qualification vs company certification
Your 2079 award is a personal qualification. Separately, any business or sole trader that services stationary F gas equipment owned by other people needs company certification. To get it, the business must show it has enough qualified staff and a written procedure for safe handling. For RACHP work gov.uk names Refcom, F-Gas Register (Quidos) and Bureau Veritas as certification bodies, and company certification must be renewed every three years.
Great Britain, Northern Ireland and the EU
Great Britain now runs its own F gas regime, regulated by the Environment Agency, SEPA, Natural Resources Wales and OPRED. Northern Ireland stays within the EU F gas and ODS system, so businesses registered there deal with the Northern Ireland Environment Agency. Gov.uk also says that a UK F gas certificate, whether held by a company or an individual, is not valid for work in the EU. In the EU, Regulation (EU) 2024/573 has also made certification compulsory for technicians working on equipment that uses alternative refrigerants. Check gov.uk for any changes to the GB rules before you plan your training.
F-Gas exam format
Each category has two parts. The knowledge test is taken online through City & Guilds’ e-volve system under closed-book conditions. The practical assessment is carried out at the training centre and observed by a qualified assessor, with no more than three candidates per assessor. You need to pass both parts.
Category I theory test content
The official test specification spreads the 40 Category I questions across five learning outcomes:
- Equipment components, their functions and where leaks are likely: 14 questions.
- Basic systems, terms, units and vapour compression theory: 11 questions.
- Causes and effects of global warming and climate change: 8 questions.
- Hazards and safe working practices: 5 questions.
- Causes and effects of ozone depletion: 2 questions.
The Category III test focuses on climate change, ozone depletion and safe recovery, storage and transport of recovered refrigerant. The Category IV test is weighted heavily towards climate change (8 of its 16 questions), with the rest split between units, ozone depletion, leakage risk and safe leak-checking practice.
The practical assessment
For Category I, the learning outcomes include making and checking pipework, pressure testing with nitrogen, evacuating a system, charging refrigerant, leak checking, recovering refrigerant and oil, and keeping the right records. Your centre will confirm the exact tasks and timings.
How to prepare for the F-Gas exam
- Choose the right category. If you install or service systems, Category I is the usual choice. Leak-check-only roles may need just Category IV.
- Book with an approved centre. Use the City & Guilds “Find a centre” search. Learning takes place on the job and in the classroom.
- Learn the numbers. Know how to convert a charge in kilograms into tonnes of CO2 equivalent, plus the leak-check and record-keeping thresholds.
- Revise the refrigeration cycle. Components and leakage risk make up over a third of the Category I test, and basic theory is another quarter.
- Practise timed questions. In the Category I test you have two minutes per question, so steady practice under time pressure helps.
Tips from the syllabus and common mistakes
- Use the correct CO2e formula. Divide the charge in kilograms by 1,000, then multiply by the gas’s GWP. Forgetting to divide by 1,000 is a classic slip.
- Know the leak-check intervals. Gov.uk sets checks at least every 12 months for 5 to under 50 tonnes CO2e and every 6 months for 50 to under 500 tonnes. Most systems at 500 tonnes or more need automatic leak detection. Having a leak detection system doubles the allowed interval.
- Remember the follow-up check. After you repair a leak, you must test again within a month to confirm the repair worked.
- Know your record keeping. Equipment containing 5 tonnes CO2e or more needs records of the gas type and amount, gas added, leak checks, and recovery or disposal. Records must be kept for 5 years.
- Do not mix up GWP and ODP. HFCs have no ozone depletion potential but often have a high global warming potential.
F-Gas practice questions
These original questions match the style and level of the 2079 knowledge tests. They are not taken from official papers.
Question 1
A stationary refrigeration system without automatic leak detection holds 15 kg of R404A (GWP 3,922). How often must it be checked for leaks?
- A. At least every 12 months
- B. At least every 6 months
- C. At least every 3 months
- D. No mandatory leak checks are needed
Answer: B. 15 kg ÷ 1,000 × 3,922 = 58.83 tonnes CO2e. This falls in the 50 to under 500 tonnes band, so the system needs a leak check at least every 6 months.
Question 2
An engineer will only check systems for leaks and will never break into the refrigeration circuit. Which is the minimum category they need?
- A. Category I
- B. Category II
- C. Category III
- D. Category IV
Answer: D. Category IV covers leak checking without breaking into the circuit. Category III covers recovery only, while Categories I and II also allow installation and servicing.
Question 3
Which type of refrigerant has zero ozone depletion potential but can have a high global warming potential?
- A. CFC, such as R12
- B. HCFC, such as R22
- C. HFC, such as R134a
- D. Halon, such as Halon 1301
Answer: C. HFCs contain no chlorine or bromine, so they do not damage the ozone layer. They are still powerful greenhouse gases, which is why the F gas rules control them.
Question 4
In a vapour compression system, in which component does the refrigerant absorb heat from the space or product being cooled?
- A. Condenser
- B. Evaporator
- C. Compressor
- D. Receiver
Answer: B. In the evaporator, low-pressure liquid refrigerant boils and absorbs heat. The condenser rejects that heat, and the compressor raises the vapour’s pressure and temperature.
Question 5
You have repaired a leak on a system that requires mandatory leak checks. When must the repair be checked again?
- A. Within one month
- B. At the next scheduled annual check
- C. Within six months
- D. Only if the customer reports another fault
Answer: A. Government guidance says leaks must be repaired as soon as possible and then tested again within a month to make sure the repair has worked.
Practise for the F-Gas Exam on your phone
F-Gas Prep (C&G 2079) by Studyforge Labs. F-Gas Prep (C&G 2079) offers 2,000+ original questions, realistic timed mock exams, flashcards with spaced repetition and a readiness dashboard to help you prepare for the 2079 knowledge tests.
- 2,000+ original questions
- Realistic timed mock exams
- Flashcards and spaced repetition
- Readiness dashboard
Free to download for iPhone and iPad. Full access is unlocked with an in-app purchase; the price is shown in the App Store before you buy.
Frequently asked questions
How hard is the City & Guilds 2079 F-Gas exam?
It is a Level 2 qualification designed for people who already have some practical experience in the sector. The Category I theory test has 40 multiple-choice questions in 80 minutes, and you need 24 correct to pass. You must also pass a practical assessment, so hands-on practice matters as much as revision.
Which F-Gas category do I need?
Category I covers every activity on stationary refrigeration, air conditioning and heat pump systems of any size, so installers and service engineers usually take it. Category III covers refrigerant recovery from smaller systems only, and Category IV covers leak checking without breaking into the circuit. City & Guilds no longer awards its own Category II.
How much does the F-Gas qualification cost?
City & Guilds currently lists a fee of £86.40 for Category I and £94.70 each for Categories III and IV. You book through an approved training centre, which sets its own price for training and assessment. Prices vary, so compare centres and check the official site before booking.
How long should I study for the F-Gas exam?
City & Guilds sets 30 guided learning hours for Category I and 20 hours each for Categories III and IV. Experienced engineers may need less revision, while newcomers should allow extra time for theory and hands-on practice.
Can I retake the F-Gas exam if I fail?
Yes. City & Guilds notes that its fees can change when resits are involved. Your training centre will arrange the retake and tell you the cost, so ask about resit terms before you enrol.
Is a UK F-Gas certificate valid in the EU?
No. Government guidance states that UK F gas certificates, whether held by a person or a company, are not valid for work in the EU. To work in an EU country you need a qualification and, where relevant, certification recognised by that member state. Northern Ireland follows the EU F gas system, so check local rules if you work there.
Official resources
- City & Guilds 2079 F Gas and ODS Regulations qualification page
- Gov.uk: Qualifications to work with F gas
- Gov.uk: Checking F gas equipment for leaks
- Gov.uk: Company certification to work with F gas
This guide is published by Studyforge Labs Ltd for study purposes and was last reviewed on 6 November 2026. Studyforge Labs and its apps are independent and are not affiliated with, endorsed by or connected to City & Guilds. Exam details, fees and dates can change, so always confirm them with the official sources above before you book.
