HVAC Chart 3 Pack, R-22 Superheat Subcooling Calculator, R-410a Superheat Subcooling Calculator and Duct Calculator

is very good for studying for exam.

Nice product, but subcooling side of R-410A must be a misprint. Tried getting a replacement, but it had same issue. Information on subcooling side of R-410A is not correct, and actually matches that for R-22. Compare that to the pictures on Amazon and from the manufacturer, which show legitimate values. Suspect the ones I got are either from a bad batch or are poor reproductions. Returning to Amazon, and I will try to order from another source.

I had lost the one I had right before a job. Had to use an app but I think slide rules are easier and faster. Gonna keep spares from now on. Great tools

Never thought that I needed these three but after needing one over the summer I purchased all three at once. And after playing with it them on job sites for a couple days, I honestly can't believe I how much guesswork has been going on. Best way to teach beginners to

Yes they make an app for that... but what happens when your phone dies? YOU NEED TO KEEP THESE IN YOUR BAG!

For HVAC work they are indispensable. Don't require batteries and can be used and read in DIRECT SUNLIGHT unlike phones and tablets. WIN WIN for you and me.

HVAC

Quick and easy way to check subcooling and superheat. Like that they fit in shirt pocket