Problems With Restricted HVAC Airflow

image of a blocked hvac air vent

HVAC systems rely on proper airflow to be able to perform well. Your HVAC system is capable of moving conditioned air at around 1000 cu. ft. per minute on average. The air is pushed through the filter, after which it travels through the ducts and finally out of the vents. As long as the HVAC system is working properly, the HVAC system will remain energy-efficient and require low operating costs. It will also be able to provide balanced temperatures and its components should last long. All is not perfect, however. Many homes suffer from HVAC airflow issues that cause discomfort and inconvenience. If there is a problem with uneven temperatures where certain rooms feel warmer or colder compared to others, it is likely an airflow issue.

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Why HVAC Airflow Is Important

There are certain reasons why proper airflow is a problem with your HVAC system. Here are some of the most common ones:

Restrictive HVAC Filters

image of a dirty furnace filter

The HVAC system has air filters that help trap particulates, prevent system damage, and keep indoor air clean. Air filters catch dust, dust mites, mold spores, bacteria, pet dander, pollen, carpet fibers, and tobacco smoke. Filters help promote the health of household members. However, filters do not have an unlimited function. They can only collect so much dirt and debris. When the air filters become clogged, they will restrict the flow of air. This is why air filters should be replaced regularly. How often a filter must be replaced will depend largely on certain factors such as the size of the home, number of occupants, presence of pets, etc. In general, it is recommended to check the air filter every month and to have it replaced if necessary.

Make sure that the filter you use is one that is compatible with the HVAC system. If you switch to a filter that has a high MERV rating, for example, you might experience restrictive airflow. High-MERV rating filters are indeed better at trapping airborne particles but they also tend to restrict the flow of air. This will require some adjustment to the fan speed. Additionally, high-efficiency filters often need HVAC air filter replacements more often.

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Leaking HVAC Ducts

Over the years, air ducts may begin to develop cracks, gaps, and holes. Some factors hasten this process, such as improper installation, pest infestation, quality of materials used, and excessive air pressure. Studies have shown that around 30% to 50% of air found in the ducts leaks out in the majority of homes. This posts a major issue for rooms that are farthest from the main vents. Because air is leaking, hot air may not be pushed far enough to reach outer rooms during winter. Whoever stays in these rooms will still feel cold even if the thermostat settings are set higher. The only solution to this problem is for an HVAC professional to find the HVAC ductwork leaks and seal them off permanently.

Blocked Air Vents

image of a closed hvac air vent

If one room feels colder or warmer than it should regardless of what you do to the system settings, you might want to consider checking the vents in that room. If one or several vents are blocked, airflow is restricted, which means conditioned air cannot go through properly. Check if the vents are clear and that curtains or furniture are not blocking them. Check that the grates are open as well. Once the obstruction has been removed, observe if the conditions improve. If not, the issue may be caused by another problem.

Closed Damper Valve

HVAC systems are capable of regulating airflow. How this is done will depend on the system’s design. Some systems use damper valves to regulate the flow of air. These systems can also cut off the flow if no one is using the room. Some damper valves can be regulated manually while some systems can adjust automatically, depending on the preferred thermostat setting. If you have manual dampers, check if they are in the correct position. Adjust the lever until the dampers are positioned ideally. If your automatic dampers are malfunctioning, this is likely an electronic issue. Do not work on the system yourself. Instead, call your HVAC contractor for help immediately.

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Crushed Flex Duct

Air ducts are made of different types of materials. Most are made from thick metal to make them durable. Others may be made of plastic so they can be bent easily. Although plastic is quite functional, it has a tendency to become easily damaged. The flex duct, for example, can be crushed if substantial weight is placed on it. Once the duct is deformed, it will be more difficult for conditioned air to go through. Deformed ducts can be lightly tapped to their original shape. However, if there are cracks or holes, it is better to have these fixed by a professional HVAC contractor.

Improperly Sized Ductwork

image of hvac ductwork that is leaking

There are multiple parts to HVAC systems. If some parts are not compatible with others, a problem is likely to emerge. Ducts that are too large, for example, will result in low air pressure, which means conditioned air will not be pushed efficiently to the farthest areas of the house. This is similar to attaching a large hole to a small faucet. The flow is simply too low for the outlet. If the ducts are too small, they will cause an airflow problem as well. The ductwork must be sized properly and this should only be done by an experienced HVAC contractor.

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Insufficient Return Air Vents

The HVAC system works by circulating air inside the home. This is referred to as a closed-loop system. The amount of air that comes back must be the same amount that was pushed out. If there is an imbalance, airflow will be affected significantly because air pressure is restricted. If the problem is a system design, an HVAC contractor can check the system and rectify the issue. If the problem is the lack of sufficient return vents, this problem must be diagnosed immediately so a solution can be put in place.



Airflow is an important component of every high-performance HVAC system. Poor airflow can often be observed through telltale signs such as discomfort and temperature imbalances. If you want to know what is causing the problems with the heating and cooling of your home, get in touch with an HVAC contractor. HVAC professionals know exactly what to look for to ensure that you enjoy balanced temperatures, improve the energy efficiency of your HVAC system, and reduce your energy bills.

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Call Miller Oil Company For Superior Heating & Cooling Solutions

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If you need a reliable professional to help you fix your HVAC airflow problems, call Miller Oil Company. We offer the most competitive rates and the most trusted services in Hartford County, Connecticut. All our HVAC technicians are certified, capable of performing heating and cooling tune-ups, installations, replacements, and repairs. Why suffer because of an airflow problem? Call Miller Oil Company today and let us discuss the best solutions for your home. Better yet, ask about our free, in-home estimate.

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