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Target Superheat

Updated: Jun 18, 2020

To determine the Target Superheat for an air conditioning system with a fixed orifice (such as a piston or capillary tube) measure the indoor WB (wet bulb) temperature with a digital psychrometer and the outdoor DB (dry bulb) temperature with a standard digital temperature reader. Input these temperatures in a superheat chart, calculation, app, or digital manifold set in order to determine the Target Superheat at that moment. Remember that the target superheat will change as the building lowers in WB and while charging refrigerant. The outdoor DB will general stay the same while checking the charge but it may fluctuate some.

Set the Actual Superheat as close to the Target Superheat as possible to have an accurate refrigerant charge.

Measure the indoor WB as close as possible to the inlet of the evaporator coil, preferably in the return duct a few feet prior to the coil. Measure the outdoor DB roughly one foot away from the inlet of the outdoor coil in the shade.

Example 1: Indoor WB 66° F, Outdoor DB 90° F= Target Superheat of 13 ° F

Example 2: Indoor WB 62° F, Outdoor DB 100° F= Target Superheat of X ° F

This means that the Target Superheat is too low to set the system to because the Target Superheat would be below 5° F. Your Target Superheat result may only be this low in a dry climate. A good example of this is in the state of Arizona. In this case, the technician would need to set the Actual Superheat to an inefficiently higher number in order to keep the compressor safe. Otherwise, the fixed orifice could be replaced with a TXV metering device or an accumulator tank could be added to protect the compressor. To learn more about charging refrigerant in a dry climate, read this article!

Example 3: Target Superheat Calculation instead of the Target Superheat Chart

(This calculation will get you close to the target superheat chart results but it may not be exactly the same.)

WB is 64° F, DB is 96° F

Target Superheat Formula = [(3 x WB) – 80 – DB] /2

[(3 x 64) – 80 – 96] /2 = Target Superheat

3 x 64=192, 192-80=112, 112-96=16 16/2=8° F of Target Superheat

8° F of Target Superheat

If you want to see a video on finding target superheat using the chart above-

If you want to see a video finding target superheat using a digital manifold see this video-

If you want to learn more about all the fine details on charging methods and troubleshooting, check out our book which is available on our website and on amazon. The full outline and sample pages are available here. We have a 1,000 question workbook with an answer key that you can use to apply your knowledge as well.

Check out our free quizzes to test your knowledge here!

If you want to learn the full Total Superheat Charging Method, check out this article!

If you want to learn the full Subcooling Charging Method, check out this article!

If you want to learn about Delta T, check out this article!

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If you have already purchased our book, be sure to tell local HVACR Instructors about our book and what you think of it. We would love to get the book into the hands of the next generation of HVACR Technicians!

Published: 4/15/2019

Author: Craig Migliaccio

About the Author:Craig is the owner of AC Service Tech LLC and the Author of the book “Refrigerant Charging and Service Procedures for Air Conditioning”. Craig is a licensed Teacher of HVACR, Sheet Metal, and Building Maintenance in the State of New Jersey of the USA. He is also an HVACR Contracting Business owner of 15 years and holds an NJ HVACR Master License. Craig creates educational HVACR articles and videos which are posted at &



I need help!!!!

I have a DB 89°F and a WB 80°F; plus SAT temp low side 39°F / vapor line Don't have tool to measure it.... issue is unit not overcoming and removing the amount of heat inside. Can't lower thermostat more than 81°F, because it will run for I don't know how long and still temperature would not come down.... any input? Thanks in advance


Bud E
Bud E
Jul 08, 2022

So, how do I interpret the "X" categories? My furnace is in my basement, and typically has a wet bulb reading of 60 - 62 F (measured just outside the furnace / evap coil), and remains pretty consistent throughout the summer. According to the charts, I should not have any superheat above an outdoor reading of about 85 F, but I routinely run the AC even when it's 95 outside.


Rich Bingham
Rich Bingham
May 17, 2022

Very easy to understand explanation of both split systems and mini-split systems in comparison. Well done!


How do I calculate the target superheat of a walk-in refrigerator? The charts that you have don't go below 50F


Thank you. Your Explanation is very helpful

Vasim shaikh


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