The Fresh Air Radon System Had Failed . . . But She Thought It Was Working Fine.

For 16 years she “knew” her radon system was working even when it had failed . . . and it had failed shortly after it was installed. Sixteen years earlier!

The blue-oil-filled manometer was lying to her for sixteen years, and she didn’t know it until her buyer tested for radon and found high radon levels.

When Radon System HomeMade Air Intake Filters are not serviced as required, they plug  up with dirt and airflow stops.

RESULT?  Dilution and pressurization stops causing radon to increase to maximum level

And with a blue-oil-filled U-tube manometer there isn’t a Clue that the system had failed and was not reducing radon. Instead, the raised  oil level in one leg FALSELY indicated that everything was fine.

An Early, 2004 radon installatin control panel

The Clues to this Radon System Failure are Powerfully Persuasive:

  1. A recent radon test by a prospective purchaser revealed elevated radon
  2. The label indicated that the system suction was 1″ at the time of installation, when the homemade filter was clean and flowing air.
  3. With the system currently operating, the blue-oil-filled manometer showed oil raised much higher in one leg, slightly below a “dirt ring.”
  4. The “dirt ring” location at 2.5″ well above the 1″ original reading revealed that the system had operated for an extended period at a high suction level point, causing the dirt ring to be created over a long time. with the homemade filter completely clogged.
  5. In the fairly recent past, a clothes dryer exhaust hood was mistakenly installed with a flapper that completely closed off the air intake. The original plastic air  intake had disintegrated from extended exposure to UV radiation. “Dirt rings” take a long time to be created.
  6. With the airflow completely closed off by the new clothes dryer flapper, the U tube displaced oil level was still not as high as the “dirt ring.” This proved that the airflow had been completely blocked by a clogged homemade air intake filter that was never service over the preceding 16 year period.
  7. Similar radon mitigation systems without clogged filters often create high indoor relative humidity, mold and moldy odor issues. The owner said that she never had a mold problem. This was further evidence that the radon system airflow was soon blocked by a homemade air intake filter that was never serviced. With no hot, humid air being delivered into the  home, no  mold-causing moisture was delivered. It also suggested that fan performance had declined over the 16 years.
    1. The radon mitigation system had failed within about 60-90 days of installation for reason of lack of required service.
    2. Legal conclusion? the system was intended to prevent lung cancer, but the radon system was of defective design, defective installation and included a defective warning system.
    3. The blue oil-filled U tube manometer failed to reveal to the owner that the radon system had failed. Instead it indicated that the system was operating perfectly.
    4. The home’s occupants were exposed to elevated levels of radon because of a failed radon system and defective warning device. Had an occupant contracted lung cancer, a trial lawyer could have filed a likely successful and easy-to-win tort claim against the installer.


  • Initial Vacuum Pressure =1″ with air flowing, filter not yet clogged 9-4-04
  • Current Pressure = 2.0″ airflow stopped by flapper on replacement dryer duct hood (recently replaced disintegrated  homemade filter housing)
  • “Dirt Ring” = 2.5″ created by stopping Airflow  for 16 years
  • Owner reports no  mold or high humidity issues


  • Airflow stopped for nearly 16 years
  • System stopped adding fresh air, causing radon to rise about 90 days after installation
  • Total failure of radon mitigation system
  • Warning device (U tube manometer) reported proper radon system operation. when in fact, radon mitigation system had completely failed.