An equalizer line should be used if the pressure drop between the inlet and outlet of the evaporator exceeds which pressure?

An equalizer line should be used if the pressure drop between the inlet and outlet of the evaporator exceeds which pressure?

• A. 4 psi
• B. 2 psi
• C. 6 psi
• D. 8 psi

Answer: (A)

When the evaporator coil has a noticeable pressure drop from its inlet to its outlet, the expansion device’s sensing point can no longer reflect the actual evaporator pressure accurately. This mis-sensing can cause the expansion valve to open too little or too much, leading to poor cooling, uneven saturation, and potential floodback or starvation of refrigerant. An equalizer line addresses this by connecting the evaporator outlet pressure back to the expansion valve’s sensing circuit, so the valve responds to the pressure where the refrigerant is actually expanding, not just to inlet pressure. The commonly used threshold for needing this adjustment is four psi; if the pressure drop across the evaporator exceeds four psi, an equalizer line should be used to maintain proper control and stable operation.

When the evaporator coil has a noticeable pressure drop from its inlet to its outlet, the expansion device’s sensing point can no longer reflect the actual evaporator pressure accurately. This mis-sensing can cause the expansion valve to open too little or too much, leading to poor cooling, uneven saturation, and potential floodback or starvation of refrigerant. An equalizer line addresses this by connecting the evaporator outlet pressure back to the expansion valve’s sensing circuit, so the valve responds to the pressure where the refrigerant is actually expanding, not just to inlet pressure. The commonly used threshold for needing this adjustment is four psi; if the pressure drop across the evaporator exceeds four psi, an equalizer line should be used to maintain proper control and stable operation.