How to Troubleshoot & Solve HVAC Airflow Problems
Fixing your airflow issues won’t just increase your comfort and air distribution, it will also save you money and energy at home.
Poor Airflow Signs
Here are some of the first signs and symptoms of poor airflow:
- Hot and cold spots
- Whistling from air ducts
- Drafty areas
- Pressure problems, such as slamming doors
- Weak airflow from HVAC registers
- Difficulties reaching the desired temperature
Top Causes of HVAC Airflow Problems
1. Improper Installation
According to Energy Star, over half of all new HVAC systems are improperly installed. Improper installation leads to higher energy bills, insufficient humidification, leaking ductwork, and comfort problems, such as poor airflow and air distribution.
If your HVAC system is excessively loud or you hear whistling and other strange noises, it may indicate undersized ductwork.
In some cases, you may have to retrofit your duct system to provide proper airflow and energy efficiency.
You may also have an aging HVAC system that requires a full replacement. Learn if you should repair or replace your air conditioner.
2. Leaking Air Ducts
Leaky ductwork is probably the number one cause of airflow and air distribution problems. Did you know that around 20% of the air that moves through your ductwork is lost due to cracks, gaps, and holes in the duct system (Energy Star)?
It’s a good idea to check for air leaks around all of your duct connections. You can test for air leaks around your ductwork with a thin piece of toilet paper or a lit piece of incense. Simply hold it up to the cracks and seams in your ductwork to see if there is air movement.
If the paper or smoke begins to move erratically, you have an air leak nearby. Since the typical home has duct leaks that lead to a 20% loss of conditioned air, speak with your trusted HVAC company about professional air duct sealing.
While homeowners can seal many air duct leaks themselves (with mastic sealant or aluminum foil tape, NOT duct tape), there will be many dangerous or hard-to-reach areas.
Pacific Heating & Cooling uses Aeroseal Duct Sealing Technology that seals all of your air duct leaks from the inside out. Polymer particles flow through your duct system and stick to the edges of any leaks until enough build up to completely seal the leak. Learn more about the Aeroseal duct sealing process.
3. Blocked Vents and Registers
Your HVAC system has been carefully designed. The size and number of your air ducts, vents, and registers have been carefully chosen and installed by a qualified HVAC. In order to keep your HVAC system running as it should it’s important to keep all of your vents and registers completely open and unblocked.
While it may seem intuitive to close off vents and registers in unused rooms, they are many negative repercussions of messing with the airflow and pressure inside the HVAC system. Regardless of how many vents and registers are closed or blocked, the forced air system still sends the same amount of conditioned air.
As a result of the increased pressure, duct leaks and indoor air quality problems will develop.
Here are some things you can do to improve airflow:
- Look behind furniture, rugs, and drapes for blocked return and supply vents.
- Make sure all of the vents are as clean and clear as possible.
- Check the vents and registers for a tight seal around where they connect to the wall, ceiling, or floor.
- Also, open your interior doors to facilitate airflow throughout the home.
4. Dirty Filter
Regular air filter replacements are probably the most important thing you can do to maintain and optimize your HVAC system. Dirty, clogged air filters can seriously reduce airflow. Make sure you are checking your HVAC air filter every 30 days by taking it out and holding it up to a strong light source.
If light cannot easily pass through the filter, it’s too dirty and should be replaced. The light waves that can make it through the filter represents the amount of air that can pass through.
It’s a good idea to have plenty of air filters on hand so you don’t have to drive to to the local home improvement store every month.
When shopping for air filters, keep in mind that the higher the MERV (Minimum Efficiency Reporting Value), the better the air filtration. But, you don’t want to get any filters with a MERV rating about 13 without first consulting a professional HVAC technician.
Higher MERV ratings means better air filtration, but that also means they are a lot thicker. High-efficiency air filters can severely restrict airflow. In order to accommodate thicker, more effective filters (such as HEPA filters), you may need a professional modification.
For the best air filtration without compromising airflow, we recommend purchasing replacement air filters with a MERV rating between 7 and 13. Learn more about air filtration and MERV ratings.
A dirty air filter impedes airflow, worsens indoor air quality, and increases your utility bills. Set calendar reminders to check your air filter every month. Replace as needed.
5. Dirty and Blocked Outdoor (Condenser) Unit
Too often, homeowners will try to block the unsightly outdoor HVAC unit with plants, fences, or other objects.
Dirty and blocked condenser coils can lead to:
- Degraded cooling capacity by up to 40%
- Decreased energy efficiency by about 60%
- Increased discharge pressure up to 60%, cutting refrigeration effect by 30%
- Reduced compressor power up to 70%
- Increased supply air temperature by close to 5 degrees Fahrenheit
- Increased compressor energy consumption by 30%
Source: U.S. Dept. of Energy
While the condenser unit isn’t exactly the most beautiful thing to look at, it needs space to function properly.
- Make sure you allow a minimum 2-foot clearance around the entire outdoor unit.
- Do not plant too close to the condenser unit. If you do have plants near the condenser unit, trim them back to maintain a 2-foot clearance.
- Check the condenser unit every 3 months or so for any leaves, grass clippings, trash, or debris that could be blocking airflow.
You can clear the area around your heat pump’s condenser unit and use your garden hose to wash away any dirt and debris, but deeper cleaning should be performed by a professional.
- Before cleaning around your outdoor unit, turn off power at the source.
- Use gloves to remove large pieces of debris.
- Use the low setting on your garden hose to gently wash around the unit. High-pressure water can bend and damage the delicate fins.
Click here for more information on cleaning heat pump condenser coils.
6. Dirty, Inefficient HVAC Components
In order to get the proper airflow and air distribution for proper comfort and humidification, it’s important to schedule routine maintenance tune-ups. Fall is the ideal time for heating tune-ups; spring is the ideal time for air conditioning tune-ups.
Your professional HVAC technician will inspect and clean your HVAC system to make sure there are no problems for the upcoming heating or cooling season.
In addition to cleaning your condenser and evaporator coils, your technician may also adjust the fan and blower motor to improve airflow and circulation. Annual HVAC maintenance makes sure all of your components are working safely and efficiently, including heat exchangers, star and run relays, valves, flues, operating pressure, wiring, thermostat, expansion valves, and much more.
Sign up for The Pacific Heating & Cooling Club for 2 scheduled HVAC tune-ups, 15% discount on services, exclusive warranties, and more!
Fixing Airflow Problems Recap:
- Check your air filter every 30 days; replace as necessary
- Schedule annual professional maintenance every fall (for heating) and spring (for cooling).
- Periodically check your vents, registers, condenser and indoor air handling unit for proper airflow.
Learn more about getting your home and air conditioner ready for the warmer weather.
If you have airflow issues at home, contact Pacific Heating & Cooling to inspect your HVAC and duct system.
Call Pacific Air Systems Heating & Cooling at (253) 292-3995 for 24/7 service.
Since 1984, we’ve been proudly serving our communities in Federal Way, Graham, Spanaway, University Place, Steilacoom, Sumner, Lakewood, Puyallup, Tacoma, Gig Harbor, and the surrounding area.