1. Pure Thermodynamic NRE (Benchmark)

64.5 BTU/lb

This is the locked chart value calculated strictly at:

40°F evaporator (dew) / 110°F condenser (bubble)
Zero superheat, zero subcooling.

This is the manufacturer benchmark with no field variables.

2. Field NRE (Recommended – Real World)

68–74 BTU/lb (typical measured range on good systems)

In the field we always have some superheat and subcooling. The diagnostic tool uses this simple, stable method:

Thermodynamic NRE = (Hg_sat + SH × 0.245) − Hf_liquid
Field NRE = Thermodynamic NRE × 0.965

The main diagnostic tool (r410a.htm) computes this live using the actual table data and applies the 0.965 field derating.

How to Read the Chart

• H1 = Enthalpy of liquid after the metering device (post-flash)
• H2 = Enthalpy of vapor leaving the evaporator (with measured superheat)
• NRE = H2 − H1 → Actual refrigerating effect per pound circulating.

Our Numbers for R-410A (Updated)

Type	Value	When to Use
Pure Thermodynamic NRE	64.5 BTU/lb	Benchmark / manufacturer comparison (no SH/SC at 40°F/110°F std conditions)
Field NRE (Recommended)	68–74 BTU/lb	Real-world diagnostics with measured SH & SC (thermodynamic NRE × 0.965 derating — what the tool shows as "Field NRE")
Sizing Reference NRE	~62–68 BTU/lb	Conservative value (Field NRE × 0.92) to avoid oversizing equipment

Why Field NRE Differs from Pure

The code first calculates the full Thermodynamic NRE at your actual pressures and temperatures using the table enthalpies plus a superheat correction of ×0.245 (vapor Cp for R-410A). It then applies a 0.965 derating factor for realistic field conditions (line losses, oil, etc.) to produce the "Field NRE" value shown in the tool. Sizing Reference NRE applies an additional ×0.92 factor on top of Field NRE for conservative equipment selection.

Tip: The main R-410A diagnostic tool (r410a.htm) computes the full Thermodynamic NRE from the table + 0.245 Cp, then applies the 0.965 derating. It displays the resulting Field NRE (typically 68–74 on good systems) and a separate Sizing Reference NRE (Field × 0.92).

Note: The pure value (64.5 BTU/lb) is the standard thermodynamic benchmark at 40°F/110°F saturated conditions from the table. The tool computes Thermodynamic NRE at your actual conditions (using 0.245 Cp for superheat), then derates by 0.965 for the displayed Field NRE. Values will vary with your measured superheat and subcooling.