Radon Manometer Reading Salt

A radon mitigation system is something most homeowners in St. Louis never think about until they have a problem. When you buy a house with an existing system or have one installed, the installer usually points to a small gauge on the wall and says something like "that tells you the system is working." But what does a radon manometer reading really mean, and what should you do when the numbers start to change? After years of maintaining and repairing these systems, I have se