R404A vs R448A: The Complete UK Commercial Refrigeration Comparison
R448A is the most widely recommended drop-in replacement for R404A in UK commercial refrigeration. But what exactly are the differences, how do the systems compare in practice, and what does an R404A-to-R448A retrofit actually involve? This guide gives UK engineers the technical and practical information needed to make the right decision.
R404A vs R448A: Key Technical Comparison
- GWP: R404A = 3,922 | R448A = 1,386 (65% reduction)
- Safety class: Both A1 (non-flammable)
- Composition: R404A = R125/R143a/R134a | R448A = R32/R125/R1234yf/R134a/R1234ze(E)
- Temperature glide: R404A ≈ 0.5°C (near-azeotropic) | R448A ≈ 5–6°C (zeotropic — charge as liquid)
- Capacity: R448A similar to R404A at medium temps; slight reduction at very low temps (-40°C)
- Energy efficiency: R448A typically 5–10% more efficient than R404A in medium-temp applications
- Discharge temperature: R448A runs 5–8°C higher discharge temp than R404A — check compressor limits
- Oil compatibility: Both compatible with POE oil; system flush recommended when switching
How to Retrofit R404A to R448A: UK Procedure
- Recover all R404A from the system using certified recovery equipment
- Drain and flush the oil circuit — remove all mineral/alkylbenzene oil; replace with compatible POE oil
- Pressure test with dry nitrogen (leak check)
- Evacuate to 500 microns or lower
- Charge with R448A as liquid — use siphon cylinder or inverted cylinder (R448A is zeotropic)
- Adjust TXV — R448A’s zeotropic nature and different properties usually require TXV adjustment or replacement; check OEM guidance
- Monitor discharge temperature — if exceeding compressor limit, increase condenser capacity or check refrigerant charge
- Update labels and F-Gas records
When to Use R448A vs R449A
R448A (Solstice N40) and R449A (Opteon XP40) are very similar blends with nearly identical GWP and performance. R449A is often preferred for medium-temperature supermarket display case retrofits (approved by more display case OEMs). R448A is well established for cold store, blast chilling and walk-in freezer applications. Both are UK-stocked and F-Gas compliant.
Order R404A for existing system servicing: R404A 10.9 kg from Refrigerant Gas Supplies Ltd — UK F-Gas compliant, next-day delivery. Contact us for bulk trade pricing.
Frequently Asked Questions
Is R448A a true drop-in replacement for R404A?
R448A is considered a drop-in in terms of equipment compatibility, but it is zeotropic and must be charged as liquid (unlike R404A which can be charged as vapour or liquid). TXV adjustment is typically required. A POE oil flush is recommended. It is not a zero-work retrofit but is significantly easier than a full system redesign.
Does R448A need different recovery equipment to R404A?
Standard A1-rated recovery equipment certified for HFO-blends (most modern machines from 2018 onwards) is compatible with R448A. Check your recovery machine’s refrigerant compatibility list — older machines may not be approved for HFO blends.
Is R448A available in the UK?
Yes. R448A is widely stocked by UK refrigerant suppliers. As an HFO blend with GWP 1,386, it is subject to far less quota restriction than R404A, keeping prices more stable.