R407C vs R410A: Key Differences Every UK HVAC Engineer Should Know

R407C vs R410A: Key Differences Every UK HVAC Engineer Should Know

R407C and R410A are both HFC refrigerants used in UK residential and commercial air conditioning, but they have significantly different properties, operating pressures and handling requirements. Understanding when each is used — and the practical differences when servicing — is important for any UK HVAC engineer working across different equipment generations.

R407C vs R410A: Technical Comparison

• GWP: R407C = 1,774 | R410A = 2,088
• Safety class: Both A1 (non-flammable)
• Operating pressure (0°C): R407C ≈ 5.8 barg | R410A ≈ 7.9 barg (R410A runs ~36% higher pressure)
• Temperature glide: R407C ≈ 6–7°C (zeotropic) | R410A ≈ 0°C (near-azeotropic)
• Charging method: R407C must be charged as liquid | R410A can be charged as liquid or vapour
• Cylinder type: R407C needs siphon/inverted cylinder | R410A standard cylinder
• Oil: Both use POE oil (R407C systems sometimes still have some residual mineral oil from R22 retrofits)
• Phase-down impact: Both being phased down; R410A more heavily restricted due to higher GWP

Where Each Is Typically Found

R407C is predominantly found in: older UK commercial AC systems (2000–2015), chiller systems used for R22 retrofit applications, some VRF systems of that era, and commercial fan-coil systems. It was extensively used as a direct R22 replacement where higher-pressure R410A was not suitable for existing pipework.

R410A is predominantly found in: UK residential split AC from 2000–2022, light commercial systems, most VRF systems pre-2020, and commercial chillers designed for the higher pressure.

Practical Service Differences

• Use dew/bubble point distinctions for R407C superheat/subcooling calculations
• Always charge R407C as liquid to prevent fractionation
• R410A pressure ratings on equipment are NOT suitable for R407C charge weight conversions — always use the specific system data
• R407C systems may require more frequent oil checks if originally converted from R22

Need R407C or R410A for your next service? R407C 10 kg and R410A 10 kg available from Refrigerant Gas Supplies Ltd — next-day UK delivery.

Frequently Asked Questions

Can R407C and R410A be used in the same equipment?

No. They have significantly different operating pressures and require different system designs. R410A equipment is specifically engineered for the higher pressures it operates at. Never use R410A in R407C-rated equipment or vice versa.

Is R407C being phased out in the UK?

R407C (GWP 1,774) is subject to UK F-Gas quota restrictions. Its cost has been increasing. Servicing of existing R407C systems remains legal; new AC systems typically use R32 or R410A rather than R407C.

Why does R407C need liquid charging but R410A does not?

R407C is a zeotropic blend with significant temperature glide. Drawing vapour causes fractionation — the components separate and the remaining liquid changes composition. R410A is near-azeotropic with negligible glide, so vapour withdrawal does not significantly alter its composition.