Metering Devices & Valves

  I walked into a supply house the other day and looked at a “universal” expansion valve on the shelf. The friendly guy behind the counter saw me and walked over. After saying hello, he said: “That's a great valve; it's even balanced port.” Now, I am a bit of a troublemaker. I should have […]

The following is based on a true story. No product was harmed in the making of this tech tip, and some facts may have changed to protect the guilty and because I forgot some of them. We got a job installing a new 1-to-1 split refrigeration case with R448a, and it had a typical thermostatic […]

Do you know how a solenoid valve works? Really? On the surface, I think we all understand how a solenoid valve works. The coil energizes, creating an electromagnet. That temporary magnetism lifts an iron plunger within the valve allowing refrigerant to flow. But is it really that simple? It turns out that the answer isn't […]

The most common diagnosis with expansion valves is failed closed or restricted, resulting in underfeeding of the evaporator. The symptoms are low suction, normal subcooling, and high superheat when a TXV fails “shut,” but there are some other issues to watch for that can actually result in overfeeding the coil. Schrader in the Port The […]

The TXV powerhead or power element is the part of the valve that sits on top of the valve to which the sensing bulb is attached. The powerhead provides the opening force for the valve by translating force from the bulb to a diaphragm in the element that forces the valve open. The sensing bulb […]

This tech tip comes from our contributor, compressor decapitator, and super tech Ulises Palacios. Many ductless systems and some high-efficiency unitary systems have electronic expansion valves. If you find one that is stuck closed, you may be able to get it open temporarily by putting a strong magnet like the one shown above on the […]

We get a lot of questions about both evacuation procedure and TXVs so last week we produced videos on both topics, including: • Before and after testing of piston vs. TXV • Using the Bluvac Measurequick app • Use of core remover tools for evacuation • Flowing nitrogen • creating an external equalizer port and […]

I don't do much in the way of “rack” refrigeration. However, I recently had a conversation with experienced rack refrigeration tech Jeremy Smith, and he got me thinking about EPR valves. I've heard EPR (evaporator pressure regulator) valves called suction regulators or hold back valves. In essence, they hold back against the suction line to […]