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For Sub Slab Depressurization Systems, a radon manometer (U-tube gauge) has been installed to ensure your radon system is operating. When the fluid levels of the gauge are uneven, the system is working.



NOTE: the manometer does not read radon levels.


If both sides of the fluid levels are equal at zero (0), this indicates that the system is not functioning. The first step is to make sure one side of the small plastic tubing on the manometer is inserted into the PVC pipe. Next, make sure the other side of the plastic tubing is connected vertically to the gauge itself.

Check Power Source

The next step is to check the power. Typically, the outlet is installed outside and enclosed in a clear plastic waterproof cover.


  1. Make sure the fan cord is plugged into the outlet. ;)

  2. Lift the plastic cover. If you have a GFCI receptacle, push the reset/red button until you hear a click. The fan should turn on immediately afterwards.

  3. If nothing happens, push the test button until you hear a click. In either case, the clicking sound will determine whether there is electrical power to the GFCI receptacle.


If you do not hear a click while pushing the reset and/or test button, this indicates that either the GFCI switch is defective, or there is no electrical power from the house to the exterior GFCI receptacle. If you have completed the above steps and your system is still not operating (or feel uncomfortable conducting these steps), please contact Lance Dorfi, LLC for service.

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