Radon Mitigation In New Construction: Passive System
We were called out to provide an estimate for activating a passive radon mitigation system. A passive radon mitigation system is a type of radon system typically found in newer homes. Conducting a radon test will determine if your passive system should be activated.
In this house, they have a 7-year-old daughter who is very sensitive to chemicals. They had their radon test done on Friday. It tested at 3.2 pCi/L, so they are looking to mitigate right away.
We Do Diagnostics On Every Job
At American Radon, we believe in a thorough diagnostic approach for every job, including passive systems. We have encountered so many passive systems that just are not working properly. Our mitigation process for passive systems involves more than just adding a fan. Let’s look at our mitigation process for a passive system.
Temporary Radon System
Unfortunately, we didn’t have time to do a full installation at the time of the bid. Typically, we spend half a day to a full day doing an install with diagnostics when activating a passive system. In this instance, we did have time to run a temporary system at least to start lower radon levels and determine if the passive system would operate as expected or if further troubleshooting would be needed.
Passive Radon System
Up on the roof, we located where the passive system pipe comes out through the roof. It then goes straight down two stories into the basement and the concrete slab. This system is not tied into the sump basket or sump cover, which is pretty common here.
Adding A Temporary Fan
We added a Fantech Rn2EC and set the fan to 50%.
To determine the setting, we used a smoke puffer to puff smoke at the sump basket on the opposite corner of the basement from the radon pipe. We set the radon fan so that the system was just pulling the smoke down into the sump basket.
We will let the temporary system run overnight until we can come back tomorrow.
Monitoring With EocTrackers
We’ve also set up four EcoTrackers to monitor the radon levels in the basement. Whether the radon levels drop or not will give us a pretty good idea of what we’re getting into tomorrow.
It will help us determine how much time we might spend on installation and if this system has issues that we will have to troubleshoot and figure out why it’s not working. The fact that we’re reaching from one side of the house to the other is a very good sign, though.
Day 2
All right, we are back. It is the second day.
Our temporary system brought the radon levels overnight down from 3.2 pCi/L to 0.7 pCi/L in the basement, 0.6 pCi/L on the main floor, and 0.5 pCi/L on the second story.
This tells us that our passive system will work, which is always a bit of a gamble with a passive system. Since we didn’t install it, we don’t know what will happen, but doing the temporary system gave us more confidence coming into it this morning.
Sealing Gaps And Cracks
We sealed the sump in the basement and the accessible areas like the storage room and the mechanical room by sealing the floor-to-wall joints that had opened up a little bit.
Activating The Passive System
Next, we added the radon fan to the passive system in the house’s attic by cutting out about 10-12 inches of pipe. Then we added insulation, which we pulled down over the fan so we wouldn’t get condensation dripping.
Finally, we did a max depressurization test, compared our pressure field extension numbers, and adjusted the fan potentiometer to reach our target pressure field extension.
We went from the Rn2EC cranked up to 10, pulling 42 watts to dialing it down to 22 watts using pressure field extension testing. This reduces the noise, but most importantly, it reduces the unnecessary airflow so that we’re not pulling as much conditioned air that the homeowner is paying to heat and cool from the basement.
Final Result
This home started with a radon level of 3.2 pCi/L, and their post-mitigation result was <0.3 pCi/L.
If you are looking for radon system service or installation and are in the Minneapolis, MN, area, contact us here.
