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HFC blend (zeotropic) · ASHRAE 34 safety group A1

R-407C GWP and CO₂e

R-32 / R-125 / R-134a blend — R-32/125/134a (23/25/52). Restricted. Largely a legacy and retrofit refrigerant; it is zeotropic, so a leak changes the remaining charge's composition and the system needs a full recharge rather than a top-up.

Great Britain

1,774

Computed per retained Regulation (EU) No 517/2014, Annex IV, from Annex I/II component values

EU / Northern Ireland

1,774

Computed per Regulation (EU) 2024/573, Annex VI, from Annex I/II component values

The figure is the same in both regimes. Both state their values on an IPCC Fourth Assessment Report basis for this substance, so a number quoted from AR5 or AR6 will not match the one that governs compliance.

How this number is arrived at

R-407C is a blend, so neither regulation lists a GWP for it directly. Both set out the same method — a mass-weighted average of the components — and both list the component values in their own annexes. The arithmetic is below so you can check it rather than take it on trust.

Component% by massGWP (GB)GWP (EU/NI)
R-3223%675675
R-12525%35003500
R-134a52%14301430

Great Britain: (0.23 × 675) + (0.25 × 3500) + (0.52 × 1430) = 155.25 + 875 + 743.6 = 1773.85, reported as 1774

EU / Northern Ireland: (0.23 × 675) + (0.25 × 3500) + (0.52 × 1430) = 155.25 + 875 + 743.6 = 1773.85, reported as 1774

Composition from ASHRAE Standard 34, as published in the ASHRAE Handbook—Fundamentals refrigerants chapter. Method from Regulation (EU) 2024/573 Annex VI and the retained GB Annex IV, which are worded identically.

Charge in kg → tonnes CO₂e

t CO₂e = charge (kg) × GWP ÷ 1,000. This figure, not the charge in kilograms, is what sets the statutory leak-check frequency.

Charget CO₂e (GB)t CO₂e (EU/NI)
1 kg1.771.77
2 kg3.553.55
5 kg8.878.87
10 kg17.7417.74
20 kg35.4835.48
50 kg88.7088.70
100 kg177.40177.40

Leak-check thresholds in kg

The regulations set the bands in tonnes CO₂e. Converted to a charge of R-407C, the duty starts at these weights.

BandCharge (GB)Charge (EU/NI)Check at leastWith leak detection
≥5 t CO₂e2.82 kg2.82 kgAt least every 12 monthsEvery 24 months
≥50 t CO₂e28.2 kg28.2 kgAt least every 6 monthsEvery 12 months
≥500 t CO₂e282 kg282 kgAt least every 3 monthsEvery 6 months

Automatic leak detection is mandatory at 500 tonnes CO₂e and above. Hermetically sealed equipment labelled as such is exempt below 10 tonnes CO₂e. Records must be kept for at least five years. Sources: retained Regulation (EU) No 517/2014 Articles 4–6, Regulation (EU) 2024/573 Articles 5–7, and GOV.UK guidance on checking F-gas equipment for leaks.

Where you meet R-407C

  • •R-22 retrofit on legacy chillers and heat pumps
  • •Air conditioning installed in the R-22 transition years
  • •Some air-cooled chillers and close-control units

Maintenance checklists for plant that runs on it

Chiller maintenance checklistAir-Cooled Chiller maintenance checklistCRAC Unit (Computer Room Air Conditioning) maintenance checklistAir Handling Unit (AHU) maintenance checklist
Work out a specific chargeCompare all 10 refrigerants

Frequently asked questions

What is the GWP of R-407C?
1774, and the same figure applies in Great Britain and in Northern Ireland. The source is a calculation set out in retained Regulation (EU) No 517/2014, Annex IV, from Annex I/II component values. Both regimes state their values on an IPCC Fourth Assessment Report basis for these substances, so figures quoted from AR5 or AR6 will differ from the ones that actually govern compliance.
How do I convert an R-407C charge into tonnes CO₂e?
Multiply the charge in kilograms by the GWP and divide by 1,000. A 10 kg charge of R-407C is 17.74 tonnes CO₂e in Great Britain. That figure is what sets the statutory leak-check frequency, not the charge in kilograms.
At what charge does R-407C need leak checks?
The duty starts at 5 tonnes CO₂e, which for R-407C is about 2.82 kg in Great Britain. Six-monthly checks start at 50 tonnes (28.2 kg) and quarterly at 500 tonnes (282 kg), where an automatic leak detection system also becomes mandatory. Fitting leak detection doubles the interval at every band. Hermetically sealed equipment labelled as such is exempt below 10 tonnes CO₂e.
Where is R-407C used?
R-22 retrofit on legacy chillers and heat pumps; Air conditioning installed in the R-22 transition years; Some air-cooled chillers and close-control units. Restricted. Largely a legacy and retrofit refrigerant; it is zeotropic, so a leak changes the remaining charge's composition and the system needs a full recharge rather than a top-up.