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Tech Tips:

I recently read a tech tip by Matt Bruner about using the Manual D process. In the article, he designed a duct system for a small job using a ducted mini-split. One thing I noticed about his design was that the supply and return duct velocity was fairly low compared to the arbitrary 900-feet-per-minute supply […]

What We Learned From NCI Duct / Balancing Training

In this engaging and informative episode, Bryan sits down with Elliot to discuss his recent training experience with the National Comfort Institute (NCI), covering two intensive courses on duct system optimization and residential air balancing. The conversation offers valuable insights for HVAC professionals looking to improve their technical skills and provide better service to […]

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HVAC School – For Techs, By Techs

Real training for HVAC ( Heating, Ventilation, Air Conditioning and Refrigeration) Technicians. Including recorded tech training, interviews, diagnostics and general conversations about the trade.

In this short podcast episode, Bryan breaks down the differences between a thermostatic expansion valve (TXV) and an electronic expansion valve (EEV). He highlights their strengths and weaknesses.

In the basic refrigerant circuit, the metering device drops the pressure. TXVs and EEVs are both metering devices that cause the liquid refrigerant to drop in pressure and become a liquid-vapor mixture; they control evaporator feeding and maintain a constant superheat.

TXVs achieve this by mechanical means; the bulb responds to suction line temperature and evaporator pressure at the valve. They are self-contained and easy to diagnose with basic refrigeration measurements. However, they are prone to mechanical failures, including clogged orifices and screens, cracked capillary tubes, and powerhead leaks. Installation errors are also easy to make, and TXVs can hunt in low-load conditions. Overall, failures are often mechanical and refrigerant-related. They win in the simplicity department.

EEVs receive inputs from sensors and modulate in response to those digital signals. They have a wider modulation range and maintain stable control in low-superheat applications, and they do well in conditions with highly variable loads or where coordination across multiple coils is required. EEVs come in two types: stepper motor (small, discrete steps) and PWM (controlled solenoid valves). Stepper-style EEVs excel at fine positioning, and PWM-style EEVs are in applications that require a more robust valve (like CO2 refrigeration). EEV failures are often electromechanical or related to sensor control. They win in the controllability department.

There is no “best” metering device; they merely have different strengths that make them better suited to different applications. However, EEVs are the future due to the greater degree of controllability we will need in newer equipment. Commissioning and airflow are also crucial for getting the most out of both metering device types in terms of longevity and reliability.

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TXV vs. EEV – Short #278

02/10/2026

Bryan Orr

Electric Heat Talk w/ Bert

02/05/2026

Bryan Orr