Understanding Unbalanced HVAC Duct Leakage

Posted on: 9 May 2017

Duct leaks are one of the most common sources of home energy loss. Not only that, but they increase the run times—and thus the general wear and tear—on your system. If you would like to learn more about the perils of duct leaks, as well as how to identify them, read on. This article will introduce you to the subject of unbalanced duct leakage.

Unbalanced Duct Leaks

The majority of duct leaks fall into the category of unbalanced leaks. This simply refers to the relationship between the amount of air being drawn into your HVAC system (the return side) and the amount of air being pushed out of it (the supply side). In some cases, if there are equal volumes of leakage occurring on both the return and supply sides, you would technically have a balanced leak. Of course, in practice this is almost never the case.

Effects Of Unbalanced Leaks

Regardless of which side of the system your leaks are occurring on, one thing is certain: they are costing you precious money where your energy bills are concerned. Leaks on the return side will cause air from your attic or crawlspaces to be sucked into the system—air which will require extra energy to either heat or cool. Leaks on the supply side will allow conditioned air to escape before it reaches the rooms of your home, thus requiring your system to work harder to supply that extra volume of air.

Air Pressure

The location of an unbalanced leak—in other words, whether return side or supply side—will have a noticeable effect on the air pressure inside of your home, relative to the outdoor air pressure. Return side leaks tend to cause the air pressure in your home to increase, since the blower is pushing more air out then it is able to draw in. A supply side leak, on the other hand, will lead to a lower indoor pressure.

Leak Detection

The changes in air pressure related to unbalanced duct leaks allow technicians to more easily determine where the leaks are occurring, through the use of a tool known as a manometer. This device is able to take measurements of the difference between the indoor and outdoor air pressure. Put simply, if the manometer detects a positive value, then return duct leakage is causing more of a problem. If the manometer detects a negative value, then it is clear the problem is located more on the supply side.

For additional information and advice, contact an HVAC maintenance company in your area.


Summer is Upon Us – Is Your AC Working?

Hi. My name is Laurie Waters. The HVAC contractor was just out at our house last week and did I ever get a lesson from him. You see, we had a warm spell hit and I went to turn our air conditioning on for the first time since last summer. Much to my dismay, it wasn’t working. All I got was a blast of warm air. The fan was bringing the outdoor heat inside. Thank goodness it wasn’t anything major. My unit needed Freon. While he was here, the contractor taught me how to do some routine maintenance around my unit, vents, and filters. I’m going to share this information with you. I hope you find it to be useful.

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