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Unread 03-03-2010, 06:53 AM
 
Location: Maine
3 posts, read 19,243 times
Reputation: 10
Default Radon Level

I was just wondering if anybody knew how long it shoud take to lower the radon level in my basement after installing mitigation system. First let me explain my situation. I built my house in Central Maine in 2008 and installed a passive system as I built due to neighbors telling me that they had radon problems. I then did a test with the small charcoal canisters and my level was 12.8 on one and 13 on the other. After getting the results I installed a mitigation fan in the attic and bought an electronic radon detector which read 17.2 the day I turned the fan on. It has been about 2 weeks now and my reading on the electronic radon detector ranges from 3.8 to 4.5. I was wondering if anybody has seen their level drop more than mine or is the electronic detector very sensitive?
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Unread 03-03-2010, 08:49 AM
 
Location: Midcoast Maine
4,885 posts, read 6,765,856 times
Reputation: 3149
Quote:
Originally Posted by jimich View Post
I was just wondering if anybody knew how long it shoud take to lower the radon level in my basement after installing mitigation system. First let me explain my situation. I built my house in Central Maine in 2008 and installed a passive system as I built due to neighbors telling me that they had radon problems. I then did a test with the small charcoal canisters and my level was 12.8 on one and 13 on the other. After getting the results I installed a mitigation fan in the attic and bought an electronic radon detector which read 17.2 the day I turned the fan on. It has been about 2 weeks now and my reading on the electronic radon detector ranges from 3.8 to 4.5. I was wondering if anybody has seen their level drop more than mine or is the electronic detector very sensitive?
Here's a recent thread about radon levels:

Maine Radon Levels in Homes

Hope this helps!
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Unread 03-03-2010, 08:54 AM
 
Location: New Jersey
2,510 posts, read 1,110,902 times
Reputation: 621
Quote:
Originally Posted by jimich View Post
I was just wondering if anybody knew how long it shoud take to lower the radon level in my basement after installing mitigation system. First let me explain my situation. I built my house in Central Maine in 2008 and installed a passive system as I built due to neighbors telling me that they had radon problems. I then did a test with the small charcoal canisters and my level was 12.8 on one and 13 on the other. After getting the results I installed a mitigation fan in the attic and bought an electronic radon detector which read 17.2 the day I turned the fan on. It has been about 2 weeks now and my reading on the electronic radon detector ranges from 3.8 to 4.5. I was wondering if anybody has seen their level drop more than mine or is the electronic detector very sensitive?
Hello.....my name is Mike and I am a New Jersey DEP licensed radon specialist who has been mitigating homes with elevated radon levels for 20+ years......I'll try to answer a few of your questions and maybe I can help you ? First, if your system is working properly radon levels should drop to acceptable levels within days, especially if your only at a 13. Second.....I wouldn't trust those electronic radon dectors you buy as most are very inaccurate......there is a reason an accurate radon test requires at least two days of testing and thats because grab sampling like your electronic device does just isn't accurate. Third exactly what mitigation fan (manufacturer and model) did you use and how much air your system is moving.....you can tell that by observing the water column on your manometer and checking that against the chart your mitigation fan came with. Finally.....when you installed your passive radon system at the time of construction did the builder follow the 16 step radon hazard sub-code for system installation ? If you can give me some answers for the above questions I can tell you what to do next.

Mike

Last edited by FlyersFan; 03-03-2010 at 09:04 AM..
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Unread 03-03-2010, 09:28 AM
 
Location: Maine
3 posts, read 19,243 times
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Quote:
Originally Posted by FlyersFan View Post
Hello.....my name is Mike and I am a New Jersey DEP licensed radon specialist who has been mitigating homes with elevated radon levels for 20+ years......I'll try to answer a few of your questions and maybe I can help you ? First, if your system is working properly radon levels should drop to acceptable levels within days, especially if your only at a 13. Second.....I wouldn't trust those electronic radon dectors you buy as most are very inaccurate......there is a reason an accurate radon test requires at least two days of testing and thats because grab sampling like your electronic device does just isn't accurate. Third exactly what mitigation fan (manufacturer and model) did you use and how much air your system is moving.....you can tell that by observing the water column on your manometer and checking that against the chart your mitigation fan came with. Finally.....when you installed your passive radon system at the time of construction did the builder follow the 16 step radon hazard sub-code for system installation ? If you can give me some answers for the above questions I can tell you what to do next.

Mike
Hi Mike Thanks for the reply. My fan is a Radonaway model RP260 the manometer is reading .5" and the chart for my fan says it is moving 180cfm. I don't know if that is accurate due to the fan is for 6" pipe and I have adapted that to my 4" pipe. As far as the installation I built the house and radon system myself. I did get my specs from the EPA website and I will explain my installation as best as I can. Before the concrete floor was poured for my cellar I inserted a 4" PVC Tee into the inside perimeter drain system. There is at least 6" of 3/8" crushed rock under my floor and a thick sheet of poly on top of that. I have sealed the cracks in the floor with a polyeurathane caulking and put a piece of plexiglass over my sump hole and sealed that with silicone. I have not sealed where the floor meets the walls even though most of it is tight against the walls. I then ran my pipe up through an interior wall and through the roof with as few bends as possible, I used 45 degree elbows as much as possible. As far as the electronic radon detector it is a Pro Series III Radon Monitor and it monitors the air for 48hours before it displays a reading. I don't know if you have had any experience with this model or not. I am hoping that this thing reads high due to the fact that my initial canister reading was 13 and less than a week later this electronic monitor read 17.2. I believe that my soil under my slab is very porous and the fan is probably larger than I need so the reading on the monitor is probably higher than it actually is I HOPE. I look foward to any info you can give me. If you need more info let me know.

Jim
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Unread 03-03-2010, 11:25 AM
 
Location: New Jersey
2,510 posts, read 1,110,902 times
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Quote:
Originally Posted by jimich View Post
Hi Mike Thanks for the reply. My fan is a Radonaway model RP260 the manometer is reading .5" and the chart for my fan says it is moving 180cfm. I don't know if that is accurate due to the fan is for 6" pipe and I have adapted that to my 4" pipe. As far as the installation I built the house and radon system myself. I did get my specs from the EPA website and I will explain my installation as best as I can. Before the concrete floor was poured for my cellar I inserted a 4" PVC Tee into the inside perimeter drain system. There is at least 6" of 3/8" crushed rock under my floor and a thick sheet of poly on top of that. I have sealed the cracks in the floor with a polyeurathane caulking and put a piece of plexiglass over my sump hole and sealed that with silicone. I have not sealed where the floor meets the walls even though most of it is tight against the walls. I then ran my pipe up through an interior wall and through the roof with as few bends as possible, I used 45 degree elbows as much as possible. As far as the electronic radon detector it is a Pro Series III Radon Monitor and it monitors the air for 48hours before it displays a reading. I don't know if you have had any experience with this model or not. I am hoping that this thing reads high due to the fact that my initial canister reading was 13 and less than a week later this electronic monitor read 17.2. I believe that my soil under my slab is very porous and the fan is probably larger than I need so the reading on the monitor is probably higher than it actually is I HOPE. I look foward to any info you can give me. If you need more info let me know.

Jim
So far, based upon what you have told me it sounds like you have done everything right. The manometer reading of 0.5 tells me that you have good air flow and the fan is meeting little resistance in moving the air from under the slab. I have been using Radonaway fans for 20 years and am very satisfied with the product. The RP260 should be more than enough fan to reduce your radon levels. If your "monitor" is still telling you that your average is hovering at 4 pCi/L then we only really have two reasons that what you have done isn't reducing the levels much further......1) The system is drawing air from someplace else other than under the floor
2) Your "monitor" isn't accurate. Assuming that your sump pump pit doesn't drain to an exterior location and your losing sub-slab suction I would seal the perimeter of your basement where the concrete slab meets the wall and then I would retest with a radon test kit that you can purchase at Lowes or Home Depot which is then send to a lab and see what the results are. Hope this helps.

Mike
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Unread 03-03-2010, 01:33 PM
 
Location: Maine
3 posts, read 19,243 times
Reputation: 10
Quote:
Originally Posted by FlyersFan View Post
So far, based upon what you have told me it sounds like you have done everything right. The manometer reading of 0.5 tells me that you have good air flow and the fan is meeting little resistance in moving the air from under the slab. I have been using Radonaway fans for 20 years and am very satisfied with the product. The RP260 should be more than enough fan to reduce your radon levels. If your "monitor" is still telling you that your average is hovering at 4 pCi/L then we only really have two reasons that what you have done isn't reducing the levels much further......1) The system is drawing air from someplace else other than under the floor
2) Your "monitor" isn't accurate. Assuming that your sump pump pit doesn't drain to an exterior location and your losing sub-slab suction I would seal the perimeter of your basement where the concrete slab meets the wall and then I would retest with a radon test kit that you can purchase at Lowes or Home Depot which is then send to a lab and see what the results are. Hope this helps.

Mike
I think I have all the other spots sealed up, I installed a test plug in the end of the daylight drain pipe from the perimeter drain to stop any leaks there. The only thing that I can think of is I have a daylight basement door and the perimeter drain is only +/-8" below grade but I would think that under the slab has less resistance than trying to pull air throught the soil. I guess that I thought I could monitor the level 24/7 with that monitor but it is looking like it is not that reliable. thanks for your input, If you have any more please let me know.
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Unread 03-03-2010, 01:52 PM
 
Location: Northern Maine
5,771 posts, read 6,985,015 times
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OK, Based on your description you are drawing air through a bed of crushed rock. Crushed rock is the very best radon source because it has the greatest surface area to weight ratio. I recommend you cap that radon source and keep it out of your home. Then run your fan for a few days to clear the air. You should see much lower readings or zero. Please post your results here.

You have a great drain system to convey water away from your foundation. It does not need to be vented. The vent into your cellar is the source of your radon.
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