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Improper and Unsafe Radon Mitigation Systems

I take pride in Our radon systems which are installed properly for safe and long service life. However many radon contractors use substandard materials and unsafe installation methods.

Two basic reasons for improper and unsafe radon mitigation systems:

  1. Cutting corners to save time and materials cost
  2. Ignorance and laziness; just plain not knowing or not bothering to figure out the proper way to do it.

Certifications are no guarantee for a quality or safe radon system installation. Unfortunately many guys seem to be installing the cheapest systems possible in the quickest manner possible to make a profit, most likely due to low cost bidding competition. Cheaper is most often not better. Following are some picture examples of improper and unsafe radon mitigation systems I have come across, from houses I’ve inspected or worked on or from examples on the web. Click on most pictures for larger viewing size.

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“The exhaust fan must not be located in or below a livable area” is a quote from the EPA booklet, What to Look for in a Radon Reduction System. All radon vent pipe past or on the discharge side of the radon fan is under high positive pressure. Radon fans are powerful, typically moving 100 too 250 cubic feet of air per minute; any break in the pipe or loose fitting or at worst a disconnected vent pipe would blow out high concentrations of radon into the home. For this reason proper installation requires the radon fan to be mounted on the exterior of the home or above the living area in an attic, or in a garage with no living area above it; in which case if the radon leaked out it would dissipate into the out door air or unconditioned air space that is vented to the exterior.

The the termination of the radon vent pipe. Radon vent pipes should not terminate below operational windows where the radon could potentially get back into the house through an open window or door.

The improper installation of vent pipe. A partial trap was formed in the horizontal radon vent pipe below the fan. In radon vent pipes one must always consider where the condensation collect and drain to.

Radon Vent Pipe Water Trap   trap, that will catch and hold condensation moisture pulled from the crawl space soil. A typical radon fan can pull up to several gallons of water a day from the soil depending on how much moisture is present. Proper installation requires all radon vent pipes to be pitched so that any condensation or water drains unrestricted back to the ground.  This partial blockage is not good for the fan and restricts the air flow, reducing the efficiency of the system and could get quite nasty over time.

Note on Certification and training: Most of the improper radon installations I’ve observed were installed by Certified and trained individuals or companies. In the above video you hear one of Mike Holmes inspectors, certified in radon testing saying, “The key is to make sure that the person that is actually doing the testing or doing the remediation is certified and thoroughly trained.” Certification is no guarantee the job will be done properly. The safest bet is to do your radon homework, ask questions and know what to look for in a proper radon mitigation installation.

More Improper and Unsafe Radon Mitigation System Pictures

Click to enlarge photo

Click to enlarge photo

Water trap formed in a radon vent pipe. This section of pipe could potentially pretty much completely fill with water and block of the air flow which would render the system pretty much useless. Any plumber understands this is a big no no with drain pipes. Radon vent pipes need to follow plumbing drain pipe installation for the most part because of all the moisture that is pulled through them.






Click photo to enlarge

Fan install on an angle and radon fan in a basement. In part for the same reason above all radon fans are required by the manufactures to be installed in an upright position because when installed horizontally or on an angle as this fan, condensation will pool and become trapped, filling the bottom section of the fan housing. The fan will be spinning in water, making quite a racket and fail prematurely. It also voids the fan warranty. Secondly this fan is also installed in the basement of a home – a safety issue.




horizontal radon fan improper installation

Horizontal radon fan, improper installation, voids warranty

Fan installed horizontally  and with flex duct and inside a basement. Three major problems here:

  1. Horizontal fan installation – wrong, will trap water, prematurely wear the fan out and voids warranty.
  2. Installed in basement – wrong, potential safety hazard, especially with the flimsy materials used to install this fan.
  3. Radon fan is attached with electrical tape to the plastic flex vent! This is very wrong, a safety hazard, could easily tear or come loose. This totally improper vent material should be PVC plastic pipe attached to the fan with heavy duty rubber couplings.


Using plastic flex vent for radon vent pipe is unsafe.

Using plastic flex vent for radon vent pipe is unsafe.

Here is an example I found on the web, where plastic flex pipe was used for the radon vent pipe. Also seen in the picture above. This is a thin plastic with wire inside to keep it from collapsing, insulated with fiberglass and an outer layer of this Mylar type plastic. This type of duct is commonly used and designed primarily for bathroom ventilation fan vents and larger diameter sizes are used for HVAC heating and cooling duct runs. The EPA radon mitigation standards require schedule 40 PVC pipe be used for radon vent pipes, the same pipe used for your plumbing drain pipes. This flex vent in no way compares to Schedule 40 PVC pipe as you can see. It could easily come loose, become punctured or tear, leaking out potentially very high concentrations of radon gas into the home.

Fan in basement, leaking water and radon gas

Fan in basement, leaking water and radon gas into the home.

Improperly connected radon fan. Radon fans should be attached to the PVC vent pipes with rubber couplings. Here is a radon fan at a house I inspected, where they tried to glue the fan to the pipe. This will save $15 to $20, the cost of the rubber couplings, but the fan is not properly secured. This is a safety issue, it could fall apart, it is leaking water from condensation and also leaking radon gas. Since the fan is in the basement, the radon is leaking back into the house.



improper radon vent pipe material

Schedule 20 PVC pipe vs: schedule 40 PVC pipe

Improper use of schedule 20 thin wall PVC pipe. In this picture I placed 35 pound weights on two pieces of PVC pipe to show the difference in strength of the pipes. The thinner pipe on left was flattened by the weight only, I did not push down. The thinner schedule 20 PVC pipe on the left is most commonly used for radon mitigation because it is much cheaper and easier to work with than the heavier pipe. When the thinner pipe is used anywhere other than inside wall cavities or in attics, it is an improper and unsafe installation. If it is exposed where it can be bumped into or hit it will easily crack, especially in freezing weather it is quite brittle.

If you get a radon mitigation proposal be sure ask which type of PVC pipe they will use. Most guys realize they are not using the proper pipe and will use the proper type if you insist. Most guys will also try to explain the thinner pipe is perfectly fine. Be aware there is a reason why the EPA stipulates the stronger pipe. I have seen the thinner pipe cracked in several instances. When exposed to the sun, the thinner pipe will break down and deteriorate in time from the suns UV rays. Also there are several types and qualities of the thinner pipes some of which can not really be glued because the hubs fit so loosely, which makes for loose and leaky joints and leaking radon gas.

Improperly installed horizontal radon fan, underground

Horizontal radon fan, improper installation, underground. Click to enlarge

Mud Pit Fan Enclosure  Here we have a radon fan that was mounted underground in horizontal position. Terrible idea, most certainly an improper installation. Photo credit to another radon professionals website. Appears the box has filled with water at times, and most likely water also collects in bottom half of fan, to bathe the bearings, not good. You could not expect a fan installed like this to last long at all.





bad traps in radon vent, improper installation.

Two fans, both improperly installed with bad “U” shaped traps in vent pipes below the fans.

Double Trouble  In this photo two radon fans are installed, both have large traps formed in the vent pipes. For both fans if the trap fills with water which is quite possible over time, the level of water at the top of the trap is at least a foot above each fan. This means the trap portions of the vent pipes including the fans would be filled with water. Not good at all, not to mention they would be quite loud working more like blenders than fans. Even though the fan motor bearing are sealed, they are not designed to run under water.