Need advice on my radon mitigation system...


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Old 10-22-18, 07:55 AM
T
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Need advice on my radon mitigation system...

5 years ago I bought a 7 year old house. The radon was 4.5; realtor says he has never seen a house in the area not needing mitigation.
I had the floor edges sealed and a fan put in. A 3" pipe goes into the floor and out the wall. It goes to a fan, and then up 8' to a 90 degree elbow.
The level dropped to 0.8.

Over the years the level drifted up to 1.5. The manometer has remained constant at 0.5".

Last week I noticed the fan had failed and the level was up to 6.8. I ordered a new fan and pulled out the old one. After 3 days the level is down to 1.9.

Questions...
1) While no fan is 1.9, a broken fan is 6.8. Is that due to air resistance from the fan and the 8 extra feet of pipe, or something else?
2) If I could get 1.9 all year, I would skip the fan. But I figure it is a matter of the air under the slab being warmer than the outside air (it is about 40 out now) and flowing out by convection. In the summer that flow should stop and the level should go up significantly. Does that make sense? If it does, would it make sense to install the fan in the summer and pull it out in the winter? Or something else entirely.
3) Why have my levels gone up. (4.5 to 6.8 with fan off, and 0.8 to 1.5 on). Has something gotten worse, or something else?
4) It is pretty windy where the exhaust is. The 90 elbow is perpendicular to the wind. Might the air flow be better if I turned it so it was away from the wind?
5) I needed the 8' to meet code requiring the exhaust to be away from a window. If I didn't have a fan, would I still need that?

Thanks much.
I realize that many people don't consider 6.8 to be a problem, but I would like to keep it lower anyhow.
 
  #2  
Old 10-22-18, 09:56 AM
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Originally Posted by Toller
". . . I realize that many people don't consider 6.8 to be a problem . . ."
Isn't the EPA alert/concern level still at 2.0 picoCuries per liter. and the recommended action level set at anything above 4.0 picoCuries ?

Has something changed . . . . like people who now say that some level of Radon is GOOD for you ?

I don't think so !
 
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Old 10-22-18, 10:24 AM
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As you probably already know, indoor radon concentrations vary greatly based on the season, temperature, humidity, open/closed doors, HVAC use, and probably 100 other things. It may have gone up over the years due to other construction in the area, water tables changing, etc. There's no real way to know.

For the few cents a day to run the fan, I would probably just replace it and let it run. No need to worry about it. Otherwise you'll have to keep track of the ups and downs as .

Out of curiosity, how are you measuring the radon levels currently?
 
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Old 10-22-18, 01:39 PM
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Measuring with a Airthings Digital Radon Detector.

A new house went up next door 2 years ago. That could increase my radon?
 
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Old 10-22-18, 08:19 PM
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When replacing the fan you might consider a smaller fan, lower cfm. I'm just thinking energy which is already minimal but maybe also longevity.

New homes are often constructed with passive ventilation and then evaluated to see if a fan is needed. For whatever reason yours seems to perform well in a passive mode. Since you have the capability to monitor the level I would stay with no motor for a while and record the numbers, it may prove sufficient.

Bud
 
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Old 10-23-18, 06:06 AM
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Level is up to 4.4! Apparently it was the strong wind that was powering the flow, because now that the wind is down, the level is up. I will let it go a while to see what happens, but I think my experiment is a failure.
 
  #7  
Old 10-23-18, 06:20 AM
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Originally Posted by Vermont
. . . like people who now say that some level of Radon is GOOD for you ?

I don't think so !
Yes a university study found low levels of radon (higher than the EPA recommends) caused you to build defenses against it and greatly LOWERED your risk of cancer compared to a control group living with zero radon.

"What doesn't kill you makes you stronger". I guess.
 
 

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