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Top HVAC and Refrigeration Leak Detection Methods

I don’t know what is harder: Finding or repairing a refrigerant leak!? I would say that fixing it is a bit straightforward, but detecting it is one of the hardest parts of being a technician. I guess you have to find the leak before you can repair it, right?

That can be an easy or a daunting task depending on certain factors, such as the nature of the leak and, above all, the detection method you use. For instance, some leaks will be more pronounced than others. They might make noise, cause an oil leak or produce some smell, making your work simpler. On the other hand, some leaks might be tiny and might require more advanced and specialized tools to detect.

Is Leak Detection Important?

I know it is part of your job to detect refrigerant leaks, but why is it necessary? First and foremost, safety. Most of the refrigerants are not ozone-friendly – actually, some have been phased out, and others are being phased out for not being “green” enough. When these gases are released into the atmosphere, they cause the depletion of the ozone layer causing global warming. It’s a whole lecture on global warming; let’s not get into the details.

Secondly, to minimize operating costs and maximize energy efficiency. A leaking refrigerant will cause a conditioning unit to consume more energy, and consequently, the operation costs will shoot. Compliance could be another reason. Some states, regions, countries require regular leak inspections.

HVAC Leak Detection Methods

There are different methods you can use to detect leaks in a conditioning unit. Here are some of the top techniques you can use.

1.  The Soap Bubble Method


Technicians all over the world have used this method for decades now. It is as straightforward as it sounds – all you need is to apply or spray soapy water on the points of interest to see if there are any leaks.  If there are any leaks, bubbles should appear (hence soap bubble). The method is the cheapest of them all since you only need soapy water (you can make it on your own or purchase a soap bubble meant specifically for refrigerant leak detection).

The only drawback with this method is that it is ineffective under certain conditions. For instance, it might not be the best method for tiny leaks or under windy conditions. The best way is to combine the soap bubble method with another method (probably, an electric leak detection method).

2.  Ultraviolet/Fluorescent Dye Method

As the name suggests, the dye method uses a dye injected into the system and circulated with the refrigerant in question. If there are any leak points, the dye will also try to escape. Using a UV lamp, you can be able to identify the leaking points.

The downside of this method is that it’s messy, and the dye tends to affect the long-term operation and performance of the HVAC system in question.

3.  Nitrogen Detection Method

Nitrogen can also be used to detect refrigerant leaks. All you need to do is replace the refrigerant (works best with Freon) with nitrogen. Nitrogen is usually held at a higher pressure, and in case there are any leaks, they will be audible. All you need to do is listen to the noise(s) and mark off the leaking points. You can also use pressure gauges…pressure changes indicate a leak in the system.

This method can be quite costly, but the results are reliable.

4.  Electronic Leak Detection Methods

Electronic detection techniques are the most accurate and efficient methods of detecting refrigerant leaks. Here are some of the common electronic detection methods.

Corona-Suppression Method (Negative Corona)

This technology is a bit traditional, but it gets the job done. The instrument uses two electrodes with a current of a known baseline passing between the two electrodes. If there’s a leak present, the refrigerant will pass through the electrodes and, in turn, interfere with it (it causes a drop in the current). The drop in current will sound an alarm. The more the interference, the higher the concentration and the larger the refrigerant leak.

The disadvantage of the corona suppression method is that it tends to produce some false positives.

The Heated Diode Method

This technology involves heating the refrigerant until its molecules break apart into chlorine and fluorine ions (most refrigerants are made up of chlorine and fluorine). These electronic detectors are designed to detect chlorine and fluorine ions and produce an audible alarm if there’s a leak.

Compared to the corona-suppression method, the diode heated technique is much more improved, and the false alarms are significantly reduced.

Ultrasonic Technology

This method detects any noise produced by leaking refrigerants. These kinds of devices will detect ultrasonic noises that the human ear can’t hear. These devices are also sensitive to pressure.

Infrared Method 

Infrared technology involves applying infrared light to detect a refrigerant. If there’s a leak, the refrigerant will absorb the infrared light, and the device will measure the degree of change in the concentration of the refrigerant. Devices using this kind of technology are very sensitive and accurate.


Elitech IR-200 is a portable refrigerant leak detector with a superior combination of infrared and heated diode sensors. This leak detector combines infrared and heated diode sensors which can easily switch between two modes. It can easily find refrigerant leaks on commercial refrigeration systems, restaurant soda machines, or any other system.

Now, to the most important question, which is the best detection technique? Some technicians swear by some of the older techniques, but the electronic leak detection methods are the most suitable. They are efficient, fast, accurate, and safe.

With all said and done, the best leak detection method should be based on your individual needs and applications. There’s no one-size-fits-all method – every technique is ideal depending on a specific application.

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