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R-404A Diagnostic Tool

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View R-404A NRE Explanation

R-404A Diagnostic Tool

All calculations use PSIA • Most gauges read PSIG (14.7 psi atmospheric)

Loading R-404A thermodynamic data...

Quick Load Realistic Calgary Scenarios

Suction Pressure
Suction Line Temp (°F)
Liquid Pressure
Liquid Line Temp (°F)
System Capacity (tons) — optional
Discharge Line Temp (°F) — optional
Return Air Wet Bulb (°F) — optional
Return Air Dry Bulb (°F) — optional
Ambient Condition

Session History & Running Average (0)

No diagnostics run yet.

Important Notes for R-404A

Near-azeotropic blend — moderate temperature glide (~0.5–1°F).
Use dew point for superheat and bubble point for subcooling.
Higher operating pressures than R-22.
GWP = 3,922.
Requires POE oil. Liquid charging recommended.

References & Data Sources

NIST Chemistry WebBook – R-404A Thermophysical Properties: https://webbook.nist.gov/chemistry/fluid/ (select R-404A)
Chemours / DuPont R-404A Thermodynamic Properties (NIST REFPROP validated)
Lemmon, E.W., Huber, M.L., McLinden, M.O. NIST Standard Reference Database 23: REFPROP, Version 10.0
ASHRAE Handbook – Fundamentals (2021)
Typical operation in ASHRAE Climate Zone 7 (Calgary region)

R-404A PT Chart

Temperature (°F)	Liquid psig	Vapor psig

Liquid (Bubble Point) & Vapor (Dew Point) • Moderate glide (~0.5–1°F) Typical field gauges: suction 70–85 psig (40–45 °F), liquid 250–340 psig (95–110 °F)