F-Gas Leak Checking Frequency in the UK (2026): CO₂e Thresholds, Records, and When Leak Detection Is Mandatory

If you manage, own, or maintain air conditioning or heat pump equipment in a commercial building, F-gas compliance is not optional. The rules are not based on how “big” a system feels, or even its cooling capacity. They are based on the refrigerant charge expressed as tonnes of CO₂ equivalent (tCO₂e). That number drives how often you must carry out leak checks, when you must install automatic leak detection, what you must record, and what you must do if a leak is found.

This guide explains the leak-check schedule, how to calculate tCO₂e, what “mandatory leak detection” means in practice, and how to build a simple compliance programme across one site or many. It is written for UK operators and facilities teams, with practical steps you can apply across Bristol and the South West.

1) What F-gas leak checking is and why it matters

What “F-gas” means in everyday HVAC terms

In HVAC, “F-gas” is shorthand for fluorinated greenhouse gases used as refrigerants in systems such as stationary air conditioning, heat pumps, and refrigeration. Refrigerant is contained inside a sealed circuit, but that does not mean leaks are impossible. Thermal cycling, vibration, corrosion, poor installation practices, and age can all create leakage points over time.

Leak checking is the structured process of detecting, recording, and fixing refrigerant leaks. It supports compliance, but it also protects reliability. A system that is losing refrigerant will generally become less stable and may run inefficiently until it fails or stops meeting comfort conditions.

Which equipment is in scope

The leak-check duties are written to cover multiple categories of equipment, including stationary air-conditioning equipment and stationary heat pumps. If the equipment is fixed to the building and contains F-gas, you should assume it is in scope until you have confirmed otherwise.

Why facilities teams should care beyond “tick-box compliance”

Most compliance failures are not caused by a lack of technical skill. They are caused by missing data, unclear ownership, and inconsistent record-keeping. A working compliance programme helps you answer five operational questions quickly:

• What equipment do we have? An accurate asset list.
• Which systems are legally in scope? Systems at or above the CO₂e thresholds.
• What is due and when? A calendar with specific dates, not vague intervals.
• Who is responsible? Operator ownership is defined for each site.
• Can we prove it? Records stored in one auditable place.

When those basics are in place, leaks tend to be caught earlier, repairs are tracked properly, and emergency call-outs become less frequent.

2) Who is responsible: “operator” duties and shared responsibilities

The operator is usually the organisation controlling maintenance decisions

Legal obligations for leak checks and records sit with the “operator”. In practical building terms, the operator is typically the organisation that controls the technical functioning of the equipment and arranges maintenance. In owner-occupied buildings, that is usually the owner. In managed estates, it may be the managing agent acting on the owner’s behalf. In some leases, the tenant is responsible for a specific plant, especially where the plant serves only their demised space.

Landlord, tenant, and managing agent scenarios

In leased buildings, the right answer depends on contracts. A practical way to reduce risk is to document, for each system, who:

• approves and pays for maintenance
• selects and instructs contractors
• holds the records and can produce them quickly
• has access to the areas where the plant is installed

If those items sit with different parties, you need a clear written process. A “grey area” is where missed leak checks and missing records are most likely.

Contractors share responsibility for identifying and stopping leaks

Service companies that install, service, maintain, repair, or decommission equipment share responsibility for identifying and stopping leaks. That matters because it changes how you should manage contractors. You are not buying a one-off task. You are buying competence, documentation, and a repeatable process.

3) The core schedule: CO₂e thresholds and leak check frequency

The thresholds that matter (5, 50, and 500 tCO₂e)

Leak check frequency is based on the CO₂e charge of the equipment. The core thresholds are:

• 5 tCO₂e (entry point for mandatory leak checks)
• 50 tCO₂e (more frequent checks)
• 500 tCO₂e (highest frequency and mandatory automatic leak detection)

Automatic leak detection, when installed, doubles the maximum interval between leak checks. This reduces how often manual leak checks must be carried out, but it does not remove the need for good record keeping or a clear response process.

At-a-glance table: convert the rules into a site calendar

Hermetically sealed equipment and the 10 tCO₂e exception

Leak check requirements do not apply to hermetically sealed equipment if it contains less than 10 tCO₂e and is labelled as hermetically sealed. “Hermetically sealed” is not a casual description. Guidance sets criteria, including that the part containing F-gas is permanently sealed (for example, welded or brazed shut) and that the product has a tested leak rate below a defined limit.

For facilities teams, the practical rule is: if you are relying on the hermetically sealed exception, you should be able to point to a clear label and supporting manufacturer information. If you cannot, treat the system as non-hermetically sealed for compliance planning.

What 5 tCO₂e looks like in kilograms (why you should never guess)

The CO₂e thresholds translate into very different kilogram thresholds depending on the refrigerant. Two examples that frequently matter for building operators:

• R410A: the 5 tCO₂e threshold can be reached at around 2.4 kg of refrigerant charge. That is why some older or larger comfort-cooling systems fall into mandatory leak checking even when the charge weight seems modest.
• R32: The 5 tCO₂e threshold is around 7.4 kg of charge. Lower-GWP refrigerants typically require a higher kg charge to hit the same CO₂e threshold.

Many commercial sites have a mix of refrigerants and system types. The only reliable approach is to calculate CO₂e for each system and store it in your asset register.

If you want the government’s plain-English overview of responsibilities and leak-checking triggers, see Checking F gas equipment for leaks.

4) How to calculate tonnes CO₂e for your equipment (step-by-step)

Step 1: gather the minimum data set for each system

To calculate tCO₂e, you need three data points:

• Refrigerant type (for example R410A, R32, R134a)
• Total refrigerant charge (kg) for the system or circuit
• GWP for that refrigerant

You can often find the refrigerant type and charge on the equipment label. If the label is missing or incomplete, use commissioning documents, O&M manuals, or a contractor’s service records. If you still cannot confirm the total charge, treat this as a priority data gap, because you cannot schedule compliance work accurately without it.

Step 2: convert kilograms into metric tonnes

CO₂e calculations use metric tonnes. Convert kilograms to tonnes by dividing by 1,000.

Step 3: multiply by the refrigerant’s GWP

CO₂e is calculated by multiplying the mass of refrigerant (in metric tonnes) by the refrigerant’s GWP.

Worked examples that facilities teams can copy into a spreadsheet

Example A: 2.4 kg of R410A

1. Convert kg to tonnes: 2.4 ÷ 1,000 = 0.0024 tonnes
2. Multiply by GWP (2,088): 0.0024 × 2,088 = 5.01 tCO₂e

This system is just over 5 tCO₂e, so it should be placed into the 5–49 tCO₂e compliance category.

Example B: 10 kg of R404A

1. Convert kg to tonnes: 10 ÷ 1,000 = 0.01 tonnes
2. Multiply by GWP (3,922): 0.01 × 3,922 = 39.2 tCO₂e

This sits in the 5–49 tCO₂e bracket (maximum 12 months between leak checks, or 24 months with automatic leak detection).

Example C: 7.4 kg of R32

1. Convert kg to tonnes: 7.4 ÷ 1,000 = 0.0074 tonnes
2. Multiply by GWP (675): 0.0074 × 675 = 4.99 tCO₂e

This is effectively the 5 tCO₂e threshold in kg terms for R32. Some smaller R32 systems are below this threshold, but you must confirm your actual charge and refrigerant type.

How to structure calculations for multi-splits and VRF/VRV systems

For larger commercial plants, the “system” is often best managed as a set of identifiable circuits or outdoor systems. Your aim is not to debate where one system ends and another begins. You aim to ensure that each refrigerant circuit has:

• a known refrigerant type
• a known total charge
• a calculated CO₂e value
• a clear leak-check schedule
• a record history you can audit

If your site has multiple tenants and shared risers, it is worth agreeing on asset boundaries early. Otherwise, record keeping becomes fragmented, and compliance control becomes unclear.

5) When leak detection is mandatory, and what it means in practice

The 500 tCO₂e trigger is a hard line

If equipment contains 500 tCO₂e or more, an automatic leak detection system must be fitted (including for stationary refrigeration, air conditioning, and heat pump equipment). For facilities teams, this is the point where “manual checks on a calendar” is no longer enough. You need both an alarmed detection system and a defined response process.

Leak detection must alert the right person, not just exist.

Leak detection systems must alert the operator, or a service company responsible for the equipment if a leak is detected. The alert requirement matters operationally. Alarms should route to an inbox or monitoring point that is staffed, and the response should be tied to a defined action (for example: dispatch engineer, isolate equipment, risk assess occupied areas, update records).

Leak detection systems must be function-checked

Automatic leak detection is not “fit and forget”. Guidance requires leak detection systems (on equipment above the threshold) to be checked at least once every 12 months to ensure proper functioning. Electrical switchgear is treated differently, but most HVAC operators will be dealing with comfort cooling and heat pump plants rather than switchgear.

Should you install leak detection below 500 tCO₂e?

Below 500 tCO₂e, automatic leak detection is not mandatory. Some organisations still choose to install it on critical plant because it can:

• Reduce the maximum interval between leak checks by doubling the allowed gap
• reduce the time between a leak starting and someone responding
• support internal sustainability reporting and refrigerant loss tracking

This tends to be most valuable where downtime is expensive or where the plant serves sensitive environments (for example, IT rooms, laboratories, healthcare storage). For general comfort cooling, the decision is often a balance between risk, budget, and how difficult it is to access the plant for scheduled checks.

6) What a compliant leak check involves (and what happens if you find a leak)

Direct and indirect methods: what “a check” can include

Mandatory leak checks can be carried out using “direct” methods (detecting leaks at potential leakage points using appropriate tools) and “indirect” methods (checking system parameters and performance indicators that may show leakage). Practical compliance usually combines both approaches. A contractor who only does indirect checks without targeted direct inspection on known leak points is often missing the spirit of leak prevention.

What you should expect from a professional site visit

A compliant visit should produce two outputs: an engineering outcome (leaks found or not found) and a documentation outcome (records updated). For most commercial buildings, a structured visit includes:

• confirming equipment ID, refrigerant type, and CO₂e charge
• reviewing records and identifying missing data
• inspecting accessible leak points (valves, joints, service ports, flare connections, branch components, coils)
• using appropriate detection techniques where relevant
• recording the method, date, result, and next due date

If your records are weak, the first compliant visit often becomes a “data capture + baseline” exercise. That is normal. The goal is to turn an unknown site into a site with a controlled compliance calendar.

If a leak is found, repair without delay and complete the follow-up check

If a leak is detected, the equipment must be repaired without delay and leak checked to demonstrate that the repair has been effective. Guidance also requires an additional leak check within a month of the repair to demonstrate that the repair remains sound. Operationally, this means you should treat leak repair as a workflow, not a single job:

1. Repair the leak using qualified personnel.
2. Verify the repair is effective through appropriate leak checking.
3. Re-check within a month to confirm the system is still sound.
4. Update records (including refrigerant added or recovered and updated CO₂e if charge changed).
5. Investigate root cause if leaks recur (vibration, installation quality, corrosion, access damage, coil condition).

7) Documentation: what you must record, how long to keep it, and how to stay audit-ready

What records are required for equipment subject to leak checks

Operators must establish and maintain specific records for equipment that is subject to leak checks. In practical terms, your logbook should capture:

• quantity and type of F-gas in the equipment when installed (in kg and CO₂e)
• quantity and type of F-gas added during installation, maintenance, servicing, or due to leakage (in kg and CO₂e)
• details of companies and individuals that install, service, maintain, repair, or decommission the equipment (including certificate numbers where relevant)
• dates and results of mandatory leak checks, recovery and disposal actions at decommissioning, including quantity recovered

Record retention: plan for five years and keep it auditable

Records are expected to be retained for five years. They should be stored in a clearly auditable fashion and made available if requested. That has two practical implications:

• Choose a single “system of record”. This could be a CAFM platform, a structured spreadsheet plus PDF attachments, or a dedicated compliance folder structure. The key is consistency.
• Standardise naming and asset IDs. “Split AC in meeting room” is not an auditable identifier. Use fixed asset IDs that match labels, site plans, and contractor reports.

A logbook template you can implement quickly

Labelling: keep it visible and keep it updated

Guidance expects the label to be clearly readable and placed either adjacent to service ports or on the part that contains the F-gas. The label should remain legible under normal operational conditions for as long as the product contains F-gas. If the product or the volume of F-gas changes, the label is expected to be updated with the updated information.

From a facilities perspective, labels are not just compliance paperwork. They are the fastest way for your team and your contractor to confirm refrigerant type, charge, and CO₂e when planning checks or repairs.

8) How to build a simple F-gas compliance programme (without making it a burden)

Step 1: build or refresh the asset register

If your register is incomplete, start with a practical site walk. Capture system IDs, locations, served areas, refrigerant type, and any visible charge data. Where data is missing, record it as a gap rather than guessing. Then use the next service visit (or a dedicated compliance visit) to confirm total charges and calculate CO₂e.

Step 2: Create a compliance calendar you can actually run

For each asset, set the “latest due date” based on its CO₂e bracket. Then add internal deadlines. A simple approach that works well in practice:

• Set an internal reminder 6-8 weeks before the latest due date.
• Book visits 4 weeks before due dates to allow for access issues and follow-ups.
• After each visit, record the next due date immediately.

Step 3: Integrate leak checks into planned maintenance

The lowest-friction approach is to combine compliance leak checks with planned preventative maintenance visits wherever the schedule allows. This reduces disruption and ensures the documentation is updated as part of a routine workflow. If you need support aligning leak checks with site maintenance, start with the scope and outcomes in Air Conditioning Service & Maintenance and build your calendar from there.

Step 4: Verify your contractor’s company certification

Company certification matters. It is a legal requirement for a company (including sole traders) to be certified by an approved body to service stationary equipment containing F-gas operated by others. Use the government’s certification guidance as a checklist of what to ask for and what company certification covers: Company certification to work with F-gas.

Step 5: Make “leak response” a defined process

Write a simple internal process so there is no confusion when a leak occurs. At minimum:

1. Define who authorises repairs and call-outs.
2. Define who receives leak detection alarms (where fitted).
3. Define how follow-up checks within a month are booked and tracked.
4. Define where records are updated and who owns record quality.

This is the difference between being compliant on paper and being compliant in reality.

9) Common mistakes that cause non-compliance (and how to avoid them)

Mistaking kW-based rules for CO₂e-based rules

Facilities teams often mix up separate compliance regimes. For example, TM44 inspections use a threshold based on rated output. F-gas leak checking uses CO₂e charge thresholds. Keep them as separate workstreams with separate triggers and record sets.

Assuming “newer refrigerant” means you are exempt.

Lower-GWP refrigerants can reduce CO₂e for a given kg charge, but they do not remove obligations. The correct approach is always: confirm refrigerant type, confirm total charge, calculate CO₂e, then schedule accordingly.

Missing the follow-up check after a repair

Repairs are not the end of the compliance chain. The additional check within a month is a common failure point because it is easy to forget once the system is running again. Put follow-up checks into your calendar at the time of repair authorisation, not after the fact.

Letting records drift across emails, paper reports, and contractor portals

Scattered records create a false sense of safety. One engineer’s report in an email inbox is not an auditable record system. Centralise records and standardise how they are stored and named.

Not updating labels and CO₂e after refrigerant changes

If refrigerant is added, recovered, or replaced, the compliance picture can change. Update your CO₂e calculation and records accordingly. Where labels are expected to reflect updated information, ensure that it is captured as part of the close-out process.

Using non-certified personnel for refrigerant work

If you are offered “maintenance” that avoids proper checks and paperwork, treat it as a risk. Ask for certification evidence and for clear reporting outputs (CO₂e values, results, and next due dates). Low-price, low-documentation servicing is one of the most common routes into non-compliance.

10) Practical next steps for Bristol and South West sites

Run a one-site compliance health check

Pick a representative site and answer three questions with evidence: (1) the CO₂e charge of each system, (2) the current due date for each leak check, and (3) where the records are stored. Once you can do that reliably for one site, roll the same method across your estate.

Decide whether you need a “records rebuild”

If charge sizes, refrigerant types, or labels are missing on multiple systems, you may need a one-off data capture exercise so that future compliance becomes routine. This is often a better use of time than repeatedly trying to patch missing information at the end of each service visit.

Use specialist support when systems are complex.

Large multi-zone installations, multiple tenants, and critical environments typically need a more structured approach, including access planning and clear documentation workflows. If you need help structuring a compliant programme or aligning leak checks with maintenance, use Contact Controlled Climate Ltd to scope what you need, or review commercial air conditioning installation options if your compliance issues are driven by outdated, hard-to-service plant.

Summary

F-gas leak checking is driven by CO₂e, not system capacity. Calculate the CO₂e charge of each system, place it into the correct bracket (5-49, 50-499, or 500+ tCO₂e), and set specific due dates based on the maximum intervals. Automatic leak detection can double the interval between checks, and is mandatory at 500 tCO₂e and above. If a leak is found, repair it without delay and complete the follow-up check within a month. Keep a single, auditable record set for each asset and retain records for five years. When you run compliance as a calendar-and-records programme (not an occasional task), it becomes predictable and much easier to manage.

Frequently Asked Questions

Do all air conditioning systems need mandatory F-gas leak checks?

Not all. Mandatory leak-check intervals apply when the equipment’s refrigerant charge is 5 tCO₂e or more. You need to calculate CO₂e from the refrigerant type and total charge to be sure.

What does 5 tCO₂e mean in kilograms?

It depends on the refrigerant’s GWP. Around 2.4 kg of R410A is close to 5 tCO₂e, while R32 needs a higher kg charge (around 7.4 kg) to reach 5 tCO₂e.

If I install automatic leak detection, do I still need leak checks?

Yes. Automatic leak detection doubles the maximum interval between leak checks, and the detection system itself must also be function-checked (at least annually for most equipment).

Who is responsible for compliance in a leased building?

It depends on who acts as the operator and what the lease or service contract says. If it is unclear, document ownership for each system and agree where records will be stored.

What records do I need to keep, in plain terms?

Refrigerant type and quantity (kg and CO₂e), any refrigerant added or recovered, who worked on the system (including certification details where relevant), and the dates/results of leak checks. Keep them for five years.

What should happen when a leak is found?

Repair without delay using qualified personnel, verify the repair, then complete the required additional leak check within a month. Update records and review root cause if leaks recur.