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Thermostatic Expansion Valves

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Summary

  • Units 5 Tons and Under: treat like a fixed orifice and charge to desired superheat.
  • Units Over 5 Tons: for safety and efficiency concerns
    Replace bottom cap with adjustable cap
    Replace valve with adjustable valve

Background

Many manufacturers utilized non‐adjustable TEVs in residential and older, smaller commercial units. When replacing R‐22 with a replacement refrigerant in units with non‐adjustable TEVs, it is important to tune the system to the attributes of that replacement refrigerant. This can be done in smaller systems by charging to proper superheat, and in larger systems it is recommended to retrofit the valve to make it adjustable.

Best Practices (5 Tons and Under)

  • Treat as fixed metering device.
  • Charge to factory recommended superheat (see Bluon TdX 20 conversion guide for fixed metering device).

Best Practices (Over 5 Tons)

  • Replace bottom cap with adjustable cap, or Replace valve with adjustable valve of equivalent capacity (or one step lower).
  • Charge to factory recommended subcool, tune to superheat.

Additional Tips

  • Sporlan has adjustable bottom cap assemblies for most of their non‐adjustable valves.
  • porlan non‐adjustable TEV’s can be identified by an “N” preceding the std. valve designation.

Video

Figure 1. Non‐Adjustable TEV.