• SkillCat Team

Leak Detection Methods

Updated: 2 days ago

EPA 608 Core Chapter 38 (Take full course for free)


This module walks through the various leak detection methods used in the HVAC industry. Skip to quiz!


1. Signs of Leak


The first sign of a leak is typically a reduced cooling capacity of the HVAC equipment. This can be noticed when rooms are not sufficiently cooled, especially if it used to feel cooler at the same temperature.

The room may simply feel a bit warmer than usual even if the system’s cooling function is on. If HVAC equipment components are working properly, the issue is most likely a leak.


If you find that the system does not hold a vacuum after you evacuate it, this is also a sign of a leak in the system. A system that is leak-free would have no problem holding a vacuum.



2. Finding Leaks


The first steps to finding a leak are the following options (no equipment required):

  1. Visual inspection

  2. Audible sound


The first step is a visual inspection. When looking over the components of the system, we want to pay attention to any traces of oil on fittings. Oil residue indicates a leak.


Sometimes, a leak can be heard without using any additional equipment. You may hear a hiss, which indicates a potential leak.


Additional methods for detecting leaks are:

  1. Halide Torch

  2. Ultrasonic Leak Detector

  3. Electronic Leak Detector

  4. Soap Bubble Test

  5. Standing Pressure Test


A halide torch consists of a flame that changes color when there is a leak. But halide torches can only be used with certain refrigerants (including R-12 and R-22). Halide torches cannot be used with hydrocarbons because hydrocarbons are highly flammable.


An ultrasonic leak detector works by amplifying the sound of the gas escaping a system. This helps identify the area of leakage.


An electronic leak detector senses the presence of halide gases such as chlorine and fluorine. Both ultrasonic and electronic leak detectors point to the general area of small leaks.


After knowing the general area of the leak, we need to find the exact location of the leak. We can use the soap bubble test to pinpoint the leaks to start on making repairs.


And lastly, we can test for leaks by doing the standing pressure test. For this test, first evacuate the system. Then we will pressurize the system and use an electronic leak detector to see if there are any leaks.


We will discuss this test in detail in the next section.


To summarize, there are many ways of detecting leaks. Generally, we want to start with a visual inspection.


The most effective methods for locating the general area of a small leak are:

  1. Ultrasonic leak detectors, and

  2. Electronic leak detectors




3. Conclusion


In this module, we discussed reasons why it is necessary to perform leak tests frequently. We also went over different leak detection methods and when they should be used.


Question #1: Which of the following are not common leak locations?

  1. Piping connections

  2. HVAC fan

  3. Coils

  4. Valve connections

Scroll down for the answer...













Ozone is composed of 3 molecules of oxygen.


Question #2: What are common ways that leaks can occur?

  1. Wear and tear on old equipment

  2. Poor initial construction

  3. Holes or cracks created accidentally during construction

  4. All of the above

Scroll down for the answer...













Absorb and reflect UV rays from the sun! Ozone is essential to life on earth because it absorbs and reflects harmful UV rays from the sun.


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