BLOWER DOOR TEST & DUCT LEAKAGE TESTfor Annapolis, Baltimore, Glen Burnie (Anne Arundel County), Columbia, Hunt Valley, Reisterstown, Frederick, Bowie, Bel Air, Washington DC and the Surrounding Areas

Blower Door Testing in the Baltimore / Washington Metropolitan Area Provides a Simple Measurement of the Hourly ACH Rate of a Home.

Hydro-Serv is Certified in Infiltration & Duct Leakage - BPI ID# 5069513

Maintaining air quality is crucial, but so is receiving the heated or cooled air that just was displaced. Too much fresh air flow leads to high energy bills and uncomfortable indoor temperatures. We use a Blower Door Test to ensure the number of air changes per hour is acceptable.

What is a Blower Door Test?

A Blower Door Test (also known as Envelope Leakage) is performed by installing a frame onto a central door in the home and attaching a fan to the door. The fan depressurizes the home to a Pascal of 50. Once the home is depressurized we use an instrument called a nanometer to measure the difference in air pressure between the outside of the home and the inside of the home. We get results in ACH (air changes per hour). This is the amount of time air leaks out of a home and new air enters into the home in an hour. All homes leak and that’s normal but keeping air changes to an acceptable amount is essential since each air change creates a need to reheat or cool the new air.

Door with fan
Duct Leakage Testing materials

Duct Leakage Testing

A Blower Door Test must be used in conjunction with a Duct Tester to measure duct leakage to the outside.

Infiltration or uncontrolled air leaks is a consequence of the number and size of cracks in the building’s thermal envelope (its floor, walls, ceilings, windows, and doors) and natural and mechanical air pressure driving forces affecting the building.

Natural driving forces include wind, the “stack effect” (air motion in buildings related to indoor-to-outdoor temperature difference and height) and atmospherically vented appliances. Mechanical driving forces include fans (such as exhaust and air handler fans), duct leakage, and others.

Preparing for a Blower Door Test

Your home energy professional will perform the blower door test, including a walk-through of your home, setting up the blower door, and conducting the test.
The following steps will help prepare your home for a blower door test:

Plan a Walk-through

We inspect your premises prior to the conclusion of your walk-through. Be prepared to discuss any locations that you know will be drafty or otherwise hard to address.

Easy Access to Areas

We will request access to all areas of your home including closets, built-in cabinets, attics, crawl spaces, and any unused rooms.

All Doors and Windows are Operational

We will need to close all exterior doors and windows, open all interior doors, and close any fireplace dampers, doors, and woodstove air inlets.


Put out any Fires

If you heat with wood, be sure all fires are completely out - even coals - before we arrive. Remove any ashes from open fireplaces.


Turn Off Appliances

Set controls on all atmospheric fossil fuel appliances (e.g., furnace, water heater, fireplaces, and stoves) to ensure that they do not fire up during the test. We will return them to the original position after the test.


Set Aside at Least One Hour

Typically, a test can take up to an hour, depending on the complexity of the home.
Funiture covered in plastic

Why Choose Hydro-Serv?

With Hydro-Serv, you can rely on the following:

Hydro-Serv proudly offers professional air duct cleaning, HVAC inspections, HVAC cleaning, filter maintenance, pressure washing, exterior cleaning, and more in Baltimore, Annapolis, Columbia, Hunt Valley, Reisterstown, Frederick, Bowie, Bel Air, and the surrounding areas of Maryland.

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