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I bought an Airthings radon monitor because of that stat, and one thing that I have learned is that those mitigation systems do not necessarily work. I have a s

I bought an Airthings radon monitor because of that stat, and one thing that I have learned is that those mitigation systems do not necessarily work. I have a system that works, but initially, even though my house had a system, it did not reliably keep the radon levels below the federal action level. Barometric pressure, temperature, and HVAC all seem to have some bearing - tightening the house for air leaks actually did a lot of good in keeping levels low. Also, sump pump failures or ground water levels can "push" radon into the house. I dug a deeper sump pit and also put a secondary radon fan to pull air out of my sub-foundation drain pipes to ensure the air below the house is cycled. Still, in Boulder County, my house will fail its radon test after a 2 hour power outage. I am an evangelist for continuous radon monitoring, alerts and tests.

nancyminusone 1y ago
I bought one of those because I have a couple radium clocks and a nice sample of uraninite, which is a tiny collection compared to the real enthusiasts but probably more radioactive stuff than the average person has. Radon is in the decay chain. I've never seen above 0.7pC/L which is pretty good, although I don't know what proportion of the activity that is there is natural, or how much more it would be without the fan. I'm not sure what the natural radon levels even are in my area, I think the radon fan is just part of code here.
colordrops 1y ago
My house is a raised foundation and they covered all the ground underneath with plastic and put perforated pipes underneath that pull the air out. Radon went down 10x. The company has a 5 year guarantee.
simonsarris 1y ago
> tightening the house for air leaks actually did a lot of good in keeping levels low Wait, really? Intuitively I would expect the opposite, that a draftier house is better for radon levels indoors
- NegativeLatency 1y ago
  There's probably a tipping point between the stack effect (hot air rising and pulling on the radon) and drafts bringing in fresh air diluting the radon.
- zdragnar 1y ago
  A better seal maintains the pressure in the house better. Drafts form either from temperature differential and wind outside pushing in. Radon coming up from the ground is still heavier than air, so it won't mix in very well if it can't displace anything. It's not a perfect solution, as air movement from circulation will help it mix in, but a good envelope will help a mitigation system out quite a bit.
- AngryData 1y ago
  If too much air can leak in from too many places your exhaust fan won't be able to keep up and maintain a pressure differential across the whole area and fully cycle through the air volume. Instead of the air mass as a whole flowing towards the exhaust you will instead get mixing of inside and outside air and then pulling of a fraction of that. Ultimately failing to properly cycle the contaminated air and also spending a lot of energy on exhausting what was previously clean exterior air. With it more sealed so you can get a decent static pressure it is like flushing a clean fluid through a pipe and only really needs a little more than the pipe's volume of fluid to clear it, with it poorly sealed it is more like scooping one cup of water out of a contaminated bucket, then pouring a clean cup of water back in and letting it mix before repeating the process, with the hopeful goal of eventually having an uncontaminated bucket of clean water. It would eventually be clean enough sure, but you might have to go through 1000x the fluid volume to get to a clean enough point. Technically you could just increase your exhaust fan's power until it creates decent static pressure in even a leaky home, but you would also be exhausting a lot of the energy you put into your climate control system.

nancyminusone 1y ago

I bought one of those because I have a couple radium clocks and a nice sample of uraninite, which is a tiny collection compared to the real enthusiasts but probably more radioactive stuff than the average person has. Radon is in the decay chain. I've never seen above 0.7pC/L which is pretty good, although I don't know what proportion of the activity that is there is natural, or how much more it would be without the fan. I'm not sure what the natural radon levels even are in my area, I think the radon fan is just part of code here.

colordrops 1y ago

My house is a raised foundation and they covered all the ground underneath with plastic and put perforated pipes underneath that pull the air out. Radon went down 10x. The company has a 5 year guarantee.

simonsarris 1y ago

> tightening the house for air leaks actually did a lot of good in keeping levels low Wait, really? Intuitively I would expect the opposite, that a draftier house is better for radon levels indoors

NegativeLatency 1y ago
There's probably a tipping point between the stack effect (hot air rising and pulling on the radon) and drafts bringing in fresh air diluting the radon.
zdragnar 1y ago
A better seal maintains the pressure in the house better. Drafts form either from temperature differential and wind outside pushing in. Radon coming up from the ground is still heavier than air, so it won't mix in very well if it can't displace anything. It's not a perfect solution, as air movement from circulation will help it mix in, but a good envelope will help a mitigation system out quite a bit.
AngryData 1y ago
If too much air can leak in from too many places your exhaust fan won't be able to keep up and maintain a pressure differential across the whole area and fully cycle through the air volume. Instead of the air mass as a whole flowing towards the exhaust you will instead get mixing of inside and outside air and then pulling of a fraction of that. Ultimately failing to properly cycle the contaminated air and also spending a lot of energy on exhausting what was previously clean exterior air. With it more sealed so you can get a decent static pressure it is like flushing a clean fluid through a pipe and only really needs a little more than the pipe's volume of fluid to clear it, with it poorly sealed it is more like scooping one cup of water out of a contaminated bucket, then pouring a clean cup of water back in and letting it mix before repeating the process, with the hopeful goal of eventually having an uncontaminated bucket of clean water. It would eventually be clean enough sure, but you might have to go through 1000x the fluid volume to get to a clean enough point. Technically you could just increase your exhaust fan's power until it creates decent static pressure in even a leaky home, but you would also be exhausting a lot of the energy you put into your climate control system.