Adjusting Pressure Setpoints

Download as PDF

Summary

  • Bluon TdX 20 operates at lower pressures, increasing efficiency & system longevity.
  • Pressure controls need to be adjusted or converted for TdX 20 operating pressures.

Background

Pressure controls are utilized in a variety of HVAC-R applications to control many different system functions. Bluon TdX 20, like all R-22 replacements, operate at different pressures than R-22.

The easiest and most effective way of converting pressure setpoints is by using the “Pressure-Temperature-Pressure” method.

Example 1

An R-22 RTU has a fan-cycling control located in the discharge line and has a 210 psig setpoint. To determine the TdX 20 equivalent setpoint, use the vapor column from the TdX 20 PT chart. Setpoint should be converted to ~180 psig.

Example 2

A hot-gas bypass (HGBP) valve has a pressure setpoint of 55 psig opening. Determine the corresponding TdX 20 pressure using the vapor column. Setpoint should be converted to ~40 psig.

Additional Tips

  • Use Bluon TdX 20 PT Chart & R-22 Pressures.
  • Generally low pressure safe switches that cut out at less than 30 psig in A/C do NOT need adjustment.
  • High pressure safety controls and pressure controls in liquid line should NOT need adjusting.

Video

Figure 1. Diagram of Vapor side and Liquid side of system.

Example 1

Example 2