My Airflow Reading is Up and Down, Is It Because It’s So Windy Outside?

The short answer? Yes, wind can cause your home’s airflow reading to go up or down.

Here’s why: When wind hits the side of a home, it causes pressure changes inside the building. Changes to indoor pressure can alter air velocity, which could explain why your airflow readings are more extreme than normal.

Besides fluctuating airflow readings, you may notice temperature variations between rooms and cold drafts throughout the home on a windy day.

Your home will be most susceptible to the airflow changes caused by wind if...

1. Your HVAC system has an outdoor air intake
2. Your ductwork is not properly sealed

In this blog, we’ll explain both of these scenarios in more detail and recommend a solution on how to have more consistent airflow in your home.

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Some HVAC systems have an outdoor air intake, which brings in fresh, outside air into the home. When filtered properly, the outdoor air can improve your home’s air quality.

However, because outside air enters the intake, the airflow in the HVAC system can fluctuate on a windy day. One study found that even normal winds entering the outdoor air intake can cause air velocity to vary a great deal.

How to tell if your HVAC system has an outdoor air intake: Outdoor air intakes are located on the exterior walls of your home, near your HVAC system. They look similar to exhaust vents (like the ones used by dryers, kitchen range hoods, and bathroom fans), but they have a screen under the hood of the intake. When you put your hand under the intake hood while the furnace or air conditioner is on, you should feel air being sucked into your home.

Ducts can form holes or become disconnected over time. Additionally, the insulation around ducts can deteriorate, leaving these holes and gaps totally exposed. When unconditioned air enters leaky ducts, the pressure inside the ductwork changes, which causes the airflow velocity to fluctuate.

Because ducts are usually located in unconditioned spaces with little insulation (such as the attic), strong gusts of wind can alter the pressure of the unconditioned space and interfere with the flow of conditioned air into your home.

You may have leaky ductwork if you notice the following signs:

• Uneven temperatures throughout the house
• Excessive dust coming out of the registers
• Poor indoor air quality

If you’re worried about the fluctuating airflow readings, we recommend contacting a professional about balancing your HVAC system.

Air balancing involves modifying your HVAC system to counteract the factors that increase or decrease airflow inside your home.

After an initial inspection of your home and HVAC system, a professional may recommend the following solutions to properly balance your HVAC system:

• Adding more vents to certain rooms
• Re-installing or sealing ductwork
• Adjusting the size of certain ducts
• Adding insulation to your ductwork
• Upgrading the HVAC fan to a variable-speed model
• And more

Once the air balancing modifications have been made to your HVAC system, you’ll notice benefits such as:

• More comfortable indoor temperatures (and more consistent airflow readings)
• Lower energy bills
• Longer-lasting HVAC equipment