Nashville Home Inspector – Active Radon Mitigation System Monitor


Active Radon Mitigation System Monitor


Richard Acree

January is National Radon Action Month.  Radon mitigation systems can be either passive or active.  Both systems provide a path of least resistance outside of the home or building.  The difference is that passive systems provide a passive path only and active systems include a blower that works continuously to pull air (and radon) from under the building and exhaust it at the roof line.  Active systems also should have a monitor to verify proper operation.  Look at the picture below.  What’s wrong?

HINT:  Pulling air from beneath the building will create a pressure differential that can be monitored. 

Radon Mitigation Monitor at Zero

ANSWER:  As it shoud be (monitored).  If the monitor shows zero differential, as this monitor above does, then there is no flow through the mitigation pipe.  Without adequate flow through the mitigation pipe, radon gas may vent inside the building.  As stated earlier, radon gas follows a path of least resistance out of the ground and either into the atmosphere or inside a building.  An active system will create a flow of air from beneath the building and carry that flow outside of the building and deposit the air flow usually at the roof line.  This air flow is a path of least resistance that the radon gas will also follow. 

If the blower fails, or the circuit breaker for the system trips, or a plug is kicked out of the socket, the inline blower will be turned OFF and the system monitor will show zero differential, as it does in the picture above.  Zero differential means the blower is OFF and air is not being drawn from below the building and the air and radon from below the building may then follow the path of least resistance into the building.  That’s bad.  The EPA signs off approximately 20,000 deaths per year to lung cancer caused by excessive radon gas concentration inside buildings.  If you have an active radon mitigation system in your home or building, the inline monitor should look like the one below.  If it looks like the monitor in the picture above, with both columns at zero, follow the directions in bold print and call the installer for service. 

Active Radon Monitor

Thank you,

Richard Acree

Comments in this blog posting are the copyrighted intellectual property of Richard Acree, President, HABITEC Home and Building Inspections, LLC,  and are intended to educate and otherwise assist home owners, sellers and buyers, building owners, sellers and buyers, realtors, real estate investors, property managers, and lenders in the process of owning, buying or selling homes or commercial buildings.  HABITEC is a residential (home) and commercial building inspection company serving Middle Tennessee including Nashville, Brentwood, Franklin, Murfreesboro, Smyrna, Mt. Juliet, Hendersonville, Dickson, Belle Meade, Columbia, Spring Hill, Lebanon, Gallatin and more!  In addition to building inspections HABITEC offers Environmental Services for mold assessments, radon testing and water quality analysis.  Additional information about HABITEC can be found on our website at, or call 615-376-2753. 

Richard Acree is the author of  the HABITEC Home and Building Inspections blog at ActiveRain, WordPress, and Blogger, and Founder of the ActiveRain Group Tennessee Home and Building Inspectors.  All are welcome to join and comment on those blogs and group.   You can also follow HABITEC on Facebook and Richard on Linked.  Thank you!


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: