It usually starts the same way. A cold room pack or a run of display cabinets loses gas, the engineer finds the leak, and everyone assumes the repair ends with a straightforward recharge. Then somebody rings the wholesaler for a cylinder of R404A and discovers the answer is no longer a price. It is a question about where the gas came from, how big the system is, and what you plan to do instead.
That conversation lands on my desk most weeks now, and it always ends up in the same place: which of the three common replacement blends suits this particular system, and does retrofitting even make sense here.
R404A is not banned, but virgin R404A cannot be used to service larger systems under the GB F-Gas rules, and reclaimed or recycled gas is only allowed until 2030. The practical R404A replacement for most medium and low temperature plant is R449A or R448A, two near-identical HFO blends with about a third of the GWP. R452A keeps more of R404A's character, including its discharge temperature, and suits low temperature and transport work. None of the three is a drop-in. A proper retrofit means recovering the old gas, attending to the oil, expansion valve and controls, charging liquid, relabelling and updating your F-Gas records.
Why R404A is being squeezed
R404A earned its place because it is a forgiving gas, and for twenty years it was the default in commercial refrigeration. Its problem is arithmetic. The GOV.UK list of fluorinated gases puts R-404A at a global warming potential of 3,922, one of the highest of any refrigerant still in common use, and the same page sets the ground rules: "If you work with hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) or sulphur hexafluoride (SF6) (F gases), you must follow the guidance for F gas users, producers and traders."
The servicing rule is the one that bites. GOV.UK states: "You must not use virgin (unused) F gases to refill existing refrigeration systems" where the system contains gas equivalent to "40 tonnes or more of carbon dioxide (CO2)" and the gas has a "global warming potential above 2,500". R404A crosses that line at roughly 10 kg of charge, which covers a great many cold rooms and packs, never mind supermarket plant. The same guidance allows gas that "has been reclaimed (until 2030 only)" or "recovered and recycled" within the same limit, and it names the escape route explicitly: retrofilling with a lower-GWP refrigerant such as "HFC 448A or HFC 449A", or replacing the system (Banned F gas for refilling equipment, GOV.UK).
So the squeeze is two-sided. Virgin supply is cut off for bigger systems, and the reclaimed stock everyone now leans on is finite, dearer every year, and gone as an option at the end of the decade. The quota keeps tightening underneath it too, and we have covered the January 2027 quota step separately. Every kilo of R404A you still hold is getting rarer. Burning it into a leaky system is the worst use of it.
The three common R404A replacements compared
Three blends do almost all of the R404A retrofit work in Britain, and they are similar enough to confuse a purchasing spreadsheet whilst being different enough to matter on site. The GWP figures below come from the GOV.UK list of fluorinated gases where the blend appears on it, and from the manufacturer's own data where it does not.
| R448A | R449A | R452A | |
|---|---|---|---|
| GWP | 1,386 (GOV.UK list) | Not on GOV.UK list; Chemours quotes "as low as 1282" | 2,140 (GOV.UK list) |
| GWP cut vs R404A | Around two thirds | "67% reduction compared to R-404A/R-507" (Chemours) | "Approximately 50% lower than R-404A" (Chemours) |
| Discharge temperature | Rises; Danfoss measured +13 K in one worked example | Rises, similar order to R448A | "Closest discharge temperature match to R-404A" (Chemours) |
| Capacity and efficiency | Broadly comparable to R404A when set up correctly | "Similar capacity", "8 to 12% more energy efficiency than R-404A/R-507" (Chemours) | Closest match to R404A behaviour of the three |
| Best fit | Medium temperature cabinets, cold rooms, packs with compressor margin | Medium and low temperature DX plant, supermarkets, cold storage | Low temperature, transport refrigeration, remote condensing units, discharge-critical compressors |
One caution on the numbers. R449A does not appear on the GOV.UK list, so its GWP comes from the manufacturer, and Chemours states: "GWP as low as 1282, a 67% reduction compared to R-404A/R-507" (Opteon XP40 (R-449A), Chemours). Ask any contractor proposing a blend to put the GWP in writing against the datasheet.
R449A and R448A: the workhorses for medium and low temperature
R449A (Chemours' Opteon XP40) and R448A (Honeywell's Solstice N40) are near twins. Same A1 safety class, same family of components, almost the same GWP, and in practice they are chosen on compressor approval, wholesaler stock and the engineer's familiarity as much as on the datasheet. Chemours positions XP40 for "Low- and medium-temperature industrial direct expansion (DX) refrigeration" and says it "can replace R-22, R-404A, R-507, and R-407A in existing equipment", adding that "retrofitting with Opteon™ XP40 does not require changes to equipment, lubricants, or seals" and that "Technicians can top it off after leak repair."
Read that last claim with an engineer's scepticism. The oil usually is compatible, because these blends run on the same POE lubricants as R404A, and "does not require changes to equipment" refers to the hardware. What it does not mean is that you can decant one gas out and pour the other in. Both blends are zeotropic, they glide a few Kelvin between bubble and dew point, and that changes how the expansion valve behaves. Danfoss's guidance on moving to R448A is blunt about it: "Superheat adjustment is critical", and if adjustment alone cannot hold the valve stable, "a dedicated TXV for that refrigerant will be necessary" (Move from R404A to R448A in commercial refrigeration, Danfoss).
The other watch item is discharge temperature. These blends run hotter at the compressor discharge than R404A, and on a low temperature freezer pack that already works hard in July, that extra heat shortens compressor life. In Danfoss's worked example at minus 10°C evaporating and 35°C condensing, R448A raised discharge temperature by 13 K. On a medium temperature pack with margin in the compressor that is manageable. On a tired low temperature system it is the reason I point people at R452A.
R452A: the low temperature and transport option
R452A (Opteon XP44) is the conservative choice of the three. Its GWP of 2,140 only halves R404A's figure, so it buys less headroom against the quota. What it buys instead is behaviour. Chemours describes it as offering the "closest discharge temperature match to R-404A" and built for duties needing "low compressor discharge temperatures", which is why the transport refrigeration industry adopted it so widely: the EPA listed it as "acceptable for use in new and retrofit equipment" for "refrigerated transport (refrigerated trucks and trailers)" and "remote condensing units used in retail food refrigeration" (Chemours on the EPA SNAP listing for XP44).
On stationary plant the logic carries over. If you have a low temperature cold room or a freezer pack where the compressor already runs near its limits, or a remote condensing unit on a roof in full sun, R452A asks the least of the hardware. The trade is simple. You accept a smaller GWP cut today in exchange for not cooking the compressor. For a system you intend to keep for years, that is often the right call, and it is a conversation worth having before the gas goes in rather than after the first compressor failure.
What a proper retrofit actually involves
A retrofit done properly is half a day of methodical work, not a bottle of gas and an invoice. The shape of it:
- Find and fix the leak first. A retrofit is a refrigerant change, not a repair. Any engineer who offers to convert a system that is still losing gas is offering to convert it twice.
- Recover and weigh the R404A. Record what comes out. That gas has value as reclaimed stock and the recovery goes in your records.
- Assess the oil. POE usually stays, but oil left acidic or wet by a burnout or a long-running leak gets changed before new gas goes anywhere near it.
- Change the filter drier and sight glass. Cheap insurance, and Danfoss recommends it "to support longer system lifetime".
- Set the expansion valve and controls. Superheat, pressure switches and controller setpoints all shift with the new blend. This is where the competence shows.
- Charge liquid, weigh it in, and commission. Zeotropic blends go in as liquid, starting below the original charge weight and trimmed on performance, with discharge temperature checked under real load.
- Relabel the equipment and update the records. The next engineer to open that panel needs to know what is inside.
That last step is not just good housekeeping. GOV.UK requires operators of equipment at "5 tonnes or more of carbon dioxide" to keep "records for 5 years", covering the "quantity and type of gas in the equipment", gas "added during maintenance", and the "dates and results of all mandatory leak checks" (Record F gas in equipment you own or service, GOV.UK). A retrofit changes the type of gas, so the record and the label both change with it. Our guide to F-Gas compliance basics covers the wider duties, and what regassing actually involves is worth a read if the leak itself is still open.
When retrofit is the false economy
This is the part most guides skip, because "yes, retrofit" is an easier page to write. The honest decision rule runs on two variables: system age and leak history.
A system under eight years old, on its first leak, with clean oil and a compressor that pulls down without complaint is a strong retrofit candidate. The conversion costs a fraction of new plant and buys it a working life on a gas you can actually buy. That is the easy case.
The harder judgement is the system past ten years that has been topped up repeatedly. Each top-up was gas escaping through a leak nobody fixed, and a system with that history has usually drawn in moisture and air, run hot, and worn its compressor. Spending money converting it to R449A is polishing a component that is already dying. I have watched businesses pay for a retrofit in the autumn and a replacement the following summer, and the second invoice always stings more because they saw it coming.
There is a third case too. If the plant is old enough that replacement is genuinely on the cards within a couple of years, the retrofit spend may be better pointed at the replacement itself, because new plant on natural refrigerants like R290 or CO₂ steps out of the F-Gas quota entirely instead of renting time inside it. Our page on the repair versus replace decision covers that judgement in full. Either way, get the leak history out of the service records before you decide. The paperwork usually knows more than the sales pitch.
Frequently asked questions
Is R404A banned in the UK?
No. It remains legal to own and to use. What the GB rules ban is using virgin R404A to service or refill refrigeration systems containing 40 tonnes or more of CO₂ equivalent, which for R404A means a charge of roughly 10 kg. Reclaimed or recycled R404A can still be used, but only until 2030 under the current rules.
Can I still get R404A for my cold room?
If your system is below the 40 tonne CO₂ equivalent threshold, yes, subject to what wholesalers will sell. Above it, only reclaimed or recycled gas until 2030, and availability and price both reflect that shrinking supply. Either way, the leak that lost the gas has to be found and fixed first.
Is R449A a drop-in replacement for R404A?
Not a true drop-in. It runs on the same POE oil and Chemours says retrofitting needs no changes to equipment, lubricants or seals, but it is a zeotropic blend with temperature glide, so the expansion valve and superheat need proper adjustment and the charge goes in as liquid. Done by an F-Gas certified engineer it is routine. Done casually it runs badly and runs hot.
What is the difference between R448A and R449A?
Very little in practice. Both are non-flammable A1 blends from different manufacturers with a GWP around 1,300 to 1,400, similar capacity to R404A and better efficiency when commissioned properly. The choice usually comes down to compressor manufacturer approval, local availability and which one your engineer knows best.
Which R404A replacement should I choose for a freezer cold room?
Low temperature duty is where discharge temperature matters most, and that points at R452A, which Chemours describes as the closest discharge temperature match to R404A. If the compressor is young with margin in hand, R449A or R448A can also work and cut GWP further. It is a judgement on the specific system, not a rule from a table.
Will retrofitting stop my system leaking?
No. A retrofit changes the refrigerant, not the pipework. The leak must be located and repaired before any new gas goes in, and a pressure test and vacuum should prove the system tight. Anything else is paying to leak a more expensive refrigerant.
Getting the decision made before the gas decides for you
The businesses that come through this in good shape are the ones that know, site by site, what gas each system holds, how old the plant is and how often it has leaked. With that list in hand, the retrofit versus replace decision for each unit is an afternoon's work. Without it, the decision gets made for you on a Saturday, under pressure, with whatever gas and whoever's advice happens to be available.
If you have R404A plant with a leak or a repair pending, talk to us about commercial refrigeration repair across London and we will assess the system honestly, including telling you when a retrofit is not worth the money. And if you want that plant register and leak history kept properly across an estate, that is exactly what a refrigeration maintenance contract is for.
About the author: Ali Elm runs Be Cool Refrigeration & Air Conditioning, a family-run London firm that has been installing, servicing and repairing commercial refrigeration and air conditioning since 2004. His F-Gas certified team has delivered more than 2,000 projects across London and the South East.
Last updated: 26 September 2026
Written by
Ali Elm
Ali is the Head of Operations at Be Cool Refrigeration with over a decade of hands-on experience in HVAC and commercial refrigeration. He oversees every installation, repair, and maintenance project, making sure the work meets the highest standards. Ali holds full F-Gas certification and has worked across residential, commercial, and industrial refrigeration systems throughout London and the South East. When he is not on site, he writes these guides to help business owners and homeowners understand their cooling systems better.