A Blower Door Test – You Want One

What is a Blower Door Test?

A blower door test is a calibrated fan set up in an exterior doorway with a computer attached to it. It sucks the air out of the home (although in certain situations it can blow air in) until the house is depressurized to 50 pascals of pressure. A pascal (Pa) is a unity of air pressure. 50 pascals is a standard unit of air pressure we test and compare the total air leakage in every home to. Compare it to what? We compare it to an industry standard called Minimum Ventilation Guideline (MVG).

The idea is that you need some fresh air in your home for proper health and the operation of combustion appliances that take air from the home. Any more than that and you are just wasting energy and causing discomfort. The MVG is calculated by measuring the size of the heated space in your home and taking into account how many people live or could live in the home. Then some simple math tells us what the MVG is. Another thing the blower door tests allows us to do is find where the biggest air leaks are. We do this with a smoke tool that allows us to see the leaks when the blower door is running.

Blower door test
Pictured is a micro manometer. This is connected to the blower door and measures the amount of air loss and leakage escaping from your home.

Blower Door Test: Measuring Pressures Inside Your Home

Part of diagnosing why some rooms are not as comfortable as others are understanding the pressures that are created in one room relative to others by the duct system when the air handler is running. A digital micromanometer allows us to measure these pressures accurately. Why are they important? Because air is so light, all it needs is a slight pressure to make it flow one way or another. When we can measure that, we can understand why you are experiencing what you are and find a solution.

image of a blower door test
Pictured is a blower door set up in a doorway.
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