Market Refrigeration TXV Adjustment

This quick article was written by market refrigeration tech Clayton Peeples. Thanks, Clayton!


Adjusting the TXV should be done last after checking all other causes of the case being warm or floodback on the rack. TXVs very rarely go bad; generally, it's a dirty screen or a failed powerhead, both of which can be addressed without replacing the valve.

Before adjusting the TXV to raise the superheat, you need to ensure that the screen is clean by pumping the system down and checking the screen.

After the screen is clean and you have ensured that there is no ice in the case, then you can start by checking the superheat with your digital gauges or probes.

If the superheat is at zero, it is best to start over using the following method to prevent floodback:

Danfoss  – Turn all the way in clockwise. Then, go out 5 ¾ turns counterclockwise. Let it set and equalize, and then check after 15 mins.

Sporlan – Turn all the way in clockwise, and then go out 4 ½ turns counterclockwise. Let it set and equalize, and then check after 15 mins.

The goal is a 6-12-degree superheat. When adjusting, make minor adjustments, and then let it sit and wait for adjustments to show. 

—Clayton

Related Tech Tips

What Is Temperature Glide?
  We've all heard about glide, but what is it really, and how does it affect our system? Glide, or temperature glide, is the difference between the bubble point and the dew point of the zeotropic refrigerant mixture. Well, that wasn't very helpful, was it? All we did was introduce new terms without defining them, […]
Read more
False Alarms: The Legacy of Phosgene Gas
We’ve all been in the unenviable position of unsweating a compressor and getting blasted in the eyes with a waft of gas that smells like burning sulfur from the pits of Hades. As we stagger back, covering our noses and holding our breaths, memories of the phrase “phosphene gas” from trade school or World War […]
Read more
Drains and Double traps
Double traps are no good. That's the end of this tech tip. Okay, here's some detail: Anytime your drain goes up and down more than once, you have a double trap UNLESS you place an air vent between the two traps that vents ABOVE the drain inlet. The double trap causes drainage issues because air […]
Read more

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

loading

To continue you need to agree to our terms.

The HVAC School site, podcast and daily tech tips
Made possible by Generous support from