Superheat is a test performed on an Air Conditioning system to determine the level of refrigerant in your system. A study commissioned by Arizona Public Service, an Arizona utility, found that more than 70% of split systems tested were at least 5% low on refrigerant. Low refrigerant charge impacts compressor reliability, as well as efficiency and performance. In mild weather it is difficult to determine the refrigerant levels in a system without the superheat test.
What is superheat?
Superheat refers to the number of degrees a vapor is above its saturation temperature (boiling point) at a particular pressure.
How do I measure superheat?
The best answer is: Call a professional who has the equipment and knowledge to do the test properly.
The more complicated answer is: Superheat is determined by taking the low side pressure gauge reading, converting that pressure to temperature using a PT chart, and then subtracting that temperature from the actual temperature measured (using an accurate thermometer or thermocouple) at the same point the pressure was taken.
Why is it important to know the superheat of a system?
Superheat gives an indication if the amount of refrigerant flowing into the evaporator is appropriate for the load. If the superheat is too high, then not enough refrigerant is being fed resulting in poor refrigeration and excess energy use. If the superheat is too low, then too much refrigerant is being fed possibly resulting in liquid getting back to the compressor and causing compressor damage.
Consequences of an Improper Charge:
An undercharged system: will not only perform poorly with low efficiency, but will also suffer chronic compressor overheating. There must be adequate refrigerant returning to the compressor to carry the compressor motor heat away to be dissipated into the condenser air. Since the compressor is the last component to receive any cooling, it is the first to suffer when the charge is short. Compressor oil breakdown comes with compressor motor overheating. Chronic overheating of the oil degrades it, reducing its ability to lubricate the compressor properly. In severe cases, sludge is formed, which can negatively affect refrigerant controls such as expansion valves, check valves, and reversing valves.
Eventually, a system that is subjected to chronic overheating due to low refrigerant charge will have a major failure usually of the compressor.
An overcharged system: May lower performance and efficiency, overcharging can cause the refrigerant to flood back to the compressor crankcase during start-up, diluting the oil and causing compressor bearing damage. Overcharging can also cause refrigerant to accumulate in the compressor crankcase during the off cycle. An overcharged system, like an undercharged system, will suffer a premature compressor failure if not repaired.
There are many contractors who do not use or understand the importance of the superheat test. It is very difficult to get accurate readings and properly charge your system without this test. I highly recommend that you ask your contractor for a superheat test and if he does not use this method, find another contractor.
Fesmire Heating and Air Conditioning serving Southern Colorado, including Pueblo, Pueblo West, Penrose, Rye, Walsenburg, La Junta and more. Call Louie today! 719-240-5109