AirThings Radon sensor
 

It's an older Gen1 model, so it's not able to talk to Amazon.. :thumbup:
It's about to finish up it's 1 week calibration run.

So far, I'm liking it. I've inserted the rain record since 11/29/20 so you can see the Rain-to-Radon relationship.
Seems like water pressure increasing in the soil, might be squishing out the Radon. So the Radon up-flow rate increases.
This happens so fast, my old theory of increased water flow over granite (which has high radon content), erodes the rock, releasing more Radon might not be the whole story.
Lately, I've heard that increases in barometric air pressure can cause your basement to have more Radon. I wonder if that's accurate.?.
Seems like it might be. If the rain water pressure theory is sound.

https://ecorenovator.org/forum/attac...1&d=1607282017

That's interesting, I just finished about 8 weeks of radon testing and we are quite high, in the basement it was sometimes over 350 BQ/M3 (13 PCi/L I believe). My tester is just a small number readout so I couldn't follow the trends like yours, wish I would have found that unit first!

Radon, it's not safe!
 

Wow, 13 PCi/L is too high for comfort. Means you need some air moved out of your basement. My kid's house had about those readings and one radon pump fixed it.

My son-in-law had this one for a long time and wasn't happy with the way it worked.
I gave them my Safety Siren Pro Series3 Radon Gas Detector - HS71512 unit.
They like it because it gives them an instant display short and long term Radon.

And used my old one. Which was accidently dropped by a neighbor and badly damage during the apocalypse.

I borrowed this AirThings, updated the firmware, checked out the app, admired it, and actually got it for Christmas!
I'm really liking this, because it has cellphone alerts (it told me to turn on the heat in the basement). The limits are pre-set by the vendor. :(
It's comm is on BT, (no WiFi) and it seems to update anytime I'm at home, no need to go down to the basement.

This is a well timed post! We just bought a house two months ago. Everything was going swimmingly until inspection time rolled around. The house is only a year old, so we didn't expect anything major. Until the inspector looked at the radon monitor and said "oh wow." We had a level of 27! Yikes. Almost made me want to pull out of the deal.

However, they put in a radon fan and it's doing the job pretty well. I am closely monitoring it with the Airthings + monitor. I've really liked the monitor so far. Some thoughts:
- I see a strong correlation with rain like you do. I'm averaging around 3.5, but it jumps up to 7-8 for a day or so after a rain. I'm also wondering if the radon has a harder time getting through the wet ground, so more of it makes its way into my basement since the area below it is dry.
- I ran a 48 hour charcoal test. Over that 48 hour period, my airthings was showing a 3.6 average. The charcoal test came in at 2.1. So, I'm interested to know if the monitor is always 1.5 higher. Have you done a charcoal test with yours to compare?
- I've also noticed a relationship between air pressure in the basement and radon. As you can see, there certainly appears to be a correlation between higher pressure and higher radon. I would think it should be opposite of this. Lower pressure providing an easier path for radon to leak in, but obviously I'm wrong :-)

My Radon is:
4.0 for the 48 hours.
3.2 for the week.
2.6 for the month (and year).

Over a week ago, we got some snow, twice. Since last Friday, we've had melting of snow during the sunny days. So, the Radon has been up and down, averaging around 4.0 with the chart showing more red peaks than yellow dips.
It seems like any water going into the ground causes a Radon peak. Even small amounts. If the ground is already pretty saturated with water, it doesn't seem to take much water going down to send up a bunch of Radon.

The water table here is very close to my basement floor. I have a large pond nearby. So, when it rains, we sometimes get radon quickly.
However when the water table is lower, it can rain like crazy and we get nothing. But occasionally 24 to 48 hours later, the Stump Pumps start running! When it's sunny outside!

Regarding the air pressure. My house has an exhaust fan in the kitchen, a oil burner and a clothes dryer in the basement. Any of them can lower the pressure inside the house, causing radon to flow into the basement.
Radon is heavy, so it will pool on the floor like leaked Propane.
That's when I turn on the Radon pump in the basement. :)

If you have a radon pump or other blower etc to move a good volume of basement air outside, your average should be okay.

At the kid's house, I have their radon pump on a timer, so it's not running full time. I leave it off late at night. It runs during daytime, when people are using the basement. The Radon (was 27) stays between 3.0 & 4.0 almost all the time. If it starts going over 4.2, we run the pump for longer hours for a few days. (Their detector beeps at 4.2). Rain causes peaks there too.

I'm not sure if the New Geothermal GSHP well (or wells) 30 feet away from their house does anything to their radon levels. It's really just lowering the temperature of the groundwater. If it's a closed loop system. WHo knows?
It's just across the narrow street in front of the house.

Cheers,
Rich

When you say radon pump, are you referring to a fan that pulls air from under the slab?

I'm considering adding a fresh air system (HRV or ERV) for the basement to recycle some of the air down there and hopefully pull out a bit of the radon.

Has anyone ever put in one of these systems and has a good recommendation on brand?

Yeah, some people call them Radon Fans, but I'm not a fan of that.
I think calling them Radon pumps came about because they are installed in a hole with a Sump Pump.
Both of them pump out stuff you don't want.

Basement HRV (Heat recovery ventilation) devices that I saw online years ago,
were installed in basement windows, that were high off the floor.

Radon is very heavy, so it mostly stays on the floor. So, to pump it out,
the air-input needs to be down close to the floor.
An oil furnace or a dryer will clean out a little of your radon. But a pump
that's designed to move Radon-Air, will do a much better job.

https://ecorenovator.org/forum/showt...t=radon&page=5


Because the basement slab is warmed up to *55 F by Mother Earth, I can run
my Radon Pump, oil burner (for hot water) and laundry dryer when it's
very cold outside, and not have to worry about the basement getting too cold.
The cold air sucked into the basement is heated up to 55 F, by free heat from the earth. It's seems to be a never ending supply.
* 55 is the current temperature, it will go up and down, but mostly stays around 50 this time of year.

My kid's basement is heated because she works down there 8 hours a day.
But the Mini-Spit easily keeps the open work & rec area warm as toast.

Lately, my Radon levels have been averaging pretty low, so I don't use the Radon Pump very much.
However, Flash Flood warnings are in the forecast for tomorrow! 12-25-2020

Have a good New Year,
Rich

The flood came and the sump pumps started Saturday morning as the Radon increased.
Turned on the Radon pump yesterday for most of the day. It's back to low Radon today.
The water is still coming in, but slower now.
Moving out that basement air worked pretty well. The basement temperature is also back to normal.

https://ecorenovator.org/forum/attac...1&d=1609091119

Wouldn't I want the air out hose exiting on the floor? My thought is to pump in outside air and have the air be removed at the floor level. This would theoretically pull out more radon, right??

Yeah, that's where it's at, on the floor. That's why I keep my detector down
about 8 or 10 inches off the flood.
My home was built in 1956, so we don't need to pump IN any air. LOL!


Here's some YouTube videos that might be helpful.
https://www.youtube.com/results?sear...an+in+basement

A lot of these professional installs suck the air from under the slab.
In some cases, there can be problems with bottom of the pipe under
the floor, if water gets into the input.

I have found that sucking the cold air out of a cool basement at the floor
level, (abt 6" off the floor) will cause the cold air on the floor to flow to
the area of the suction. It will pull the cold air from the whole basement,
excluding closed rooms. Increased air flow of the coolest air removes the radon.

Changed my mind about input air
 

Today, I didn't allow enough air into the basement while running the radon fan for 4 hours. 12:00 to 16:00
Ended up with more Radon! It was pulled out of the sump holes and cracks in the floor! I created a little vacuum and got punished. No Ham radio in the basement tonight!

The radon was low at noon. But I wanted to ventilate the basement to freshen up the air. I opened the pull-down stairs to the attic, thinking cool air would flow down. But it was so hot today in the attic, there was no down-flow of attic air. It was likely a suction effect. Especially if attic vent fan turned on (auto-on at 120F).

I'm going to need some way of bringing in outside air into the basement. When it's cold outside, that will be a real problem. I don't want a lot of cold air on the basement floor while the Radon fan is running.

~~~
On another note, I need to look at the Radon after the oil burner has been running! That thing sucks too!

Cheers,
Rich

I've seen a drastic improvement after sealing all cracks in the floor. The method of construction was to pour the basement walls, then later pour the floor. That left about a quarter-inch gap around the entire perimeter. I used a radon sealing caulk (from Menards) and sealed the entire perimeter. Since doing that, my levels are rarely above 2 or so. Usually in the 1 range. I think I'm almost nearing outdoor levels for most days.

Between the fan and the sealing, I've gone from almost 30 down to 1. Pretty awesome.

Just because I was curious, when we were out of town for 10 days, I turned the radon fan off. I anticipated not much increase, but boy was I wrong. Even with the sealing, it jumped to 17. Needless to say, keeping the fan on all the time now.

The Right Stuff
 

It sounds like you're doing it right. My old basement could be sealed with a lot of work. So it's not gonna happen.

I looked at the afternoon 24 hour plot and saw a 4.6 peak at 17:30. The oil burner ran from 17:00 until 17:20. (We are trying to make this tank last until WW3 starts) ;)
It's clearly sucking up some radon and shooting some up the chimney. I'll bet most of the houses on this granite hill do the same thing.
The good news is, two of the new families on my street have installed Mini-Splits during the last month. :)
The new kids next door went with Propane heat. They are already talking about moving to Florida (from MA).
I don't blame them.

I've wondered about all those oil burners you have in that part of the world. Any affect on the air quality overall in the area?

Looking at the New Cases (of lung cancer) map, it seems okay in this area. Not too bad..
https://www.lung.org/getmedia/381ca4...0-report-final