Don’t Forget the Service Wrench

One of my most popular YouTube videos goes over how to adjust TXV superheat. It's a very simple little video that I did at my desk, and the other day I got this comment:

“Good Video but I hate to say this BUT, with the title SCHOOL, why would you show the public an instructional video depicting the use of an adjustable wrench on a valve stem? Service valves, valve stems on TXV's and Acetylene tanks should NEVER be touched with anything but a service wrench… Its hard to unlearn bad habits”

It was a well-deserved rebuke; in my haste, I used an adjustable wrench to show the adjustment of the TXV stem rather than a service wrench.

The refrigeration service wrench is as much a staple of the HVAC/R industry as a gauge manifold. It's really just a square drive ratcheting box wrench, usually with several sizes built-in with 1/4″, 3/16″, 5/16″, and 3/8″ being the most common.

There are many purposes for the refrigeration wrench, including:

  • Opening and closing acetylene tanks
  • Adjusting TXV superheat
  • Opening & closing multiposition service valves to the back seat, front seat, or neutral seat
  • Opening typical residential HVAC Service valves using a 3/16″ (liquid line) &  5/16″ (suction line) combo hex key (shown below)
  • Adjusting other square refrigeration valve stems
  • Adjusting 5/16″ square-headed blower/fan set screws (credit: Tony Hilliard)

Josh Olson also gave us a great tip for using service wrenches AND adjustable wrenches for service valves. You take the service wrench in one hand and the adjustable in the other to loosen the packing on the valve before making adjustments to the stem. You can also check out Mueller's bulletin HERE for more information.

The primary lesson is that whenever you are making an adjustment on a device, tank, etc., you want to use a tool that will do the least amount of harm by damaging the stem edges, as well as use a tool that will apply the correct amount of force without providing enough torque to break anything.

A refrigeration wrench fits the bill in many applications, and in general, getting away from adjustable wrenches is a good idea anyway.

—Bryan

 

Related Tech Tips

Air Flow and Ice - A Thought Experiment
Imagine a glass of ice sitting on a table. Now, imagine you place a lid on the glass so that all the water and ice are contained in the glass. If the ice and water are well mixed, the water and ice will both be at 32°F because the ice is slowly changing state from […]
Read more
Relative Humidity of Air Below Freezing
I was listening to someone talk about air relative humidity the other day while looking at a psychrometric chart, and he commented that the chart ends down at freezing (32°F) because “all the water freezes out of the air at that point.” I think I made this Jed Clampett face: The psychrometric chart is designed […]
Read more
Get an EEV Open (Like Magic)
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 […]
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