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How To Measure Superheat – Types Of Superheat

Measuring superheat is an important step to ensure that your cooling device is working properly and continues to do so, without any hindrance. Superheat finds its usage in cooling devices along with other physical phenomena and uses.


Let us quickly recall how the cooling system in a normal cooling device works. Note that this is necessary to know before you proceed with superheat types and measuring steps.

The refrigerant leaves the cooling unit as a liquid and this liquid refrigerant then moves through the liquid line and enters the evaporator. Now the liquid goes directly through the measuring device and its pressure also reduced. The hot air roaming in the home sucked through the return air and is added to the refrigerant when it is being transformed into a gas.

Now when all of the heat removed from the house, the refrigerant coil turns to gain heat. And when all the liquid is superheated.

The cool air makes its way out of the coil and now scatters through the entire room. Now, when the normal working conditions of the cooling device fails to operate, that’s when you need to call a technician. Before calling him, they know about all the three types of superheating and how the to superheat is measured.

How To Measure Superheat

Superheating or also known as boiling delay, or boiling retardation a phenomenon explained in physics. In this, a liquid is heated to a temperature to a point that higher than the boiling point. This state of hearing the liquid to such a temperature also known as metastate. In this stage, the boiling can occur at any stage provoked by internal or external forces.

Superheating is accomplished by boiling a homogeneous substance in a clean container. Heating can be done through the microwave. One should take care to not disturb the liquid as it may lead to an eruption of hot water which can cause burns too.

Superheating is an exception to the normal boiling rule, I.e. there are cases where liquid does not boil even the vapor pressure exceeds the atmospheric pressure of the liquid(which is the normal boiling case). The reason behind this is surface tension which prevents the growth of bubbles.

Types of superheat

The main principle in finding the fault in the working of an air conditioner is, follow the heat. One should follow the direction of heat to check if the cooling device is functioning normally or not.

  1. Evaporator superheats: For measuring the Evaporator Superheat, you may first measure the temperature of the suction line. Now, take note of refrigerant pressure (you may use a Schrader valve in the external equalizer. Take your hoses and connect everything and start the system. After running it for some time, you may take the reading of Evaporator pressure.
  2. Total Superheat: When the refrigerant makes its way through the suction line from the evaporator to the outside condensing unit, it tends to pick up more heat. To measure total superheat, first measure the temperature and pressure of the suction line at the suction valve. Now, convert the gauge pressure to the saturating temperature and subtract the value obtained from the temperature of the suction line. The number so obtained is superheat.
  3. Duct System: The technicians most commonly do not pay much heed to the superheat of a duct system. For this, you have to begin on the return side. Take a note of the air temperature which enters the return grill and after this, measure the temperature of air that enters the equipment. Subtract both the values. And take the percentage of it. Now, if the temperature gain or loss is more than 5% then you may have to get the cooling device serviced or duct repaired.

How To Calculate Superheat

You should also check on the supply side and record the temperature of air coming out from the equipment and air temperature far from the device. Subtract them and calculate the percentage. If it is more than 5%, you may wish to consider the help of a technician.

Also, have a check on the system’s static pressure. For this, received the entering and exiting pressure and add both of them together. If this value exceeds the pressure value printed by the publisher, clean the indoor coil or try changing the air


Measuring superheat and taking proper care of your cooling device is crucial to maintain the proper working of your device. We recommend you to keep a check of it on a scheduled basis to ensure that you don’t need to fix for bigger damage than what was caused.

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