Comments on: Radon Reduction From Basement Sealing – Preliminary

By: Bruce Fergusson, CIH

Bruce Fergusson, CIH — Tue, 01 Oct 2024 15:33:16 +0000

In reply to Bob Wood.

What Bob said…
You cannot do radon diagnostics to properly characterize the Pressure Field Extension (PFE) across the basement without a micro-manometer. An improperly sized radon fan will either (1) pull too much conditioned air from the home, resulting in an energy penalty, or (2) fail to reduce radon levels sufficiently.

By: Richard Raborn MD

Richard Raborn MD — Mon, 30 Sep 2024 15:30:55 +0000

In reply to Bob Wood. Thanks!

By: Bob Wood

Bob Wood — Sun, 29 Sep 2024 17:33:38 +0000

We sometimes use a product called a “green drain” …….”IF”….. you can remove the piping and place ir low enough that the piping will not interfere with its operation. This should be a trapped drain already so you should not be getting any radon back through it already. depending on the age of your building here in Ontario these drains were used to drain the foundation drains up until the mid 1970’s……

By: Richard Raborn MD

Richard Raborn MD — Fri, 27 Sep 2024 12:28:12 +0000

I have a drain for my HVAC system which has several pipes going into it. Tough to block. Thought about using a plastic sheet filled with closed foam to create a “lid”. Running Radon fan continuously in my passive under slab system seems to keep Radon levels well below 2.

By: Bob Wood

Bob Wood — Thu, 26 Sep 2024 17:31:45 +0000

If you were my client i would fix the fresh air to the large volume exhaust fan first. Then address the radon issue second. depressurization of fuel burning appliances causes carbon monoxide that can kill you and your family very fast(overnight) radon is a killer but it takes time to cause cancer. See number 2
Three things to start
1/ I believe Terry Howells company was Georgia Radon,
2/ If you have a 400 cfm kitchen exhaust fan you need to bring a fresh air vent to under the stove that the fan sits above. I am not sure but the size I believe will be a 6″ vent pipe. install a cold air trap in it to avoid un intended air movement.
3/ If your radon guy shows up without a digital manometer show him the door, smoke tests only show air movement that is occurring at that moment in time. Your radon system fan sizing needs to be sized based on worst case scenario, winter time, all exhaust fans, and all fuel burning appliances ( ie dryer fan, furnace, hot water tank, fireplaces and wood burning stoves space heaters ect) runnning.
From all our discussion, and info. I believe you do not have a radon problem you have an intermittent home depressurization problem (large CFM kitchen exhaust) that is sucking so hard on your basement is is allowing the radon system to be overpowered. If your radon guy has a grab sampler, have him sample the radon levels below the slab ……. it will be some multiple of the radon found in the home 10x -100x this home has a fairly tightly sealed slab…… 1x-10x you have some significant openings in slab that need to be found and sealed. can be under a shower in basement around the toilet or a sump lid that is not well sealed or a French drain along the wall floor joint, it could be just a gap from concrete shrinkage.

By: Bob Wood

Bob Wood — Wed, 25 Sep 2024 21:07:04 +0000

In reply to Bruce Fergusson, CIH. Thanks Bruce

By: Jim

Jim — Wed, 25 Sep 2024 14:20:05 +0000

I want to thank you for your helpful comments! The original system was installed by Southern Mechanical (apparently the radon company is no longer in business, but there is another Southern Mechanical). Just mentioning that incase there was a connection to Terry Howell.

At this time I know simply bringing in outside air is not a viable solution. It was mainly a test I wanted to try to see if it helped. Without more study I really don’t know if the lowered radon levels were simply due to mixing in lower radon air, or if it provided enough positive pressurization to help the mitigation system work better, or a combination.

I am pursuing two approaches currently. I had the recent radon company out for some discussion. The tech that came is not listed on the AARST website, but people from the company are (and the tech said that one of them was his boss). He said they would be doing more investigative work which will likely include redoing some of the sealing, and drilling some test holes for smoke suction tests. I am also talking to my HVAC provider about ERV options and make-up air options (side note I have a >400 CFM range hood). The HVAC options get pricey.

By: Bruce Fergusson, CIH

Bruce Fergusson, CIH — Tue, 24 Sep 2024 15:33:46 +0000

Bob is spot-on with the warning about humidity. I’ve seen indoor RH levels increase noticeably with residential HVAC fan running continuously for reasons that have been discussed ad nauseum in this space. Unless you have variable speed compressor that can deal with incoming moisture, be very careful.
Depending on the climate it can take a lot of latent capacity to address incoming moisture. Once dealt with a temporary pharmacy with 2K OA that required 12 tons to get it down to 50F during hot days in central KY.

By: Bob Wood

Bob Wood — Fri, 20 Sep 2024 17:45:44 +0000

Jim and Bruce: the connection from the on the return air duct to the outside, is an uncontrolled unbalanced system of introducing of outside air into a home that was done by my mentor Terry Howell on a lot of his mitigation systems that were not quite doing it for the home in terms of radon reduction.

Bruce is completely right it slightly pressurizes the home with low radon level air. What this does is reach parts of the slab that the sub slab depression radon system was not reaching to overcome the stack effect of the building. Terry was a big believer in this system but,……. the HVAC system fan was supposed to be run 100% of the time. So that is you were bringing in hot moist air in the summer, that the a/c coil would condition out the high humidity. In heating season you would see that air be mixed with warm return air…… Terry and I believed, I did not. Terry is an engineer, I am a Plumber and Steamfitter. So we did what good tradesman do, we sat down and did the math over a small bottle of Canadian Whiskey, what Terry was able to prove to me that in Atlanta ( in Canada’s winters not so much) the energy penalty was so small that it was a rounding error, Vs the high cost of going to additional radon systems or drops or tapping the block wall to reduce radon ( i have seen tapping the block wall be very successful in very difficult to mitigate homes where the block wall was measuring very hot (on a grab sampler).
I would strongly consider reinstalling this fresh air connection ( if you are willing to run the HVAC system all the time and keep your windows shut all the time) as it appeared to be working well on your home for radon reduction.

By: Richard Raborn MD

Richard Raborn MD — Fri, 20 Sep 2024 14:18:41 +0000

In reply to Allison Bailes. Airthings follows my home's air quality. I installed the UGA passive system in my slab but needed to add fan in attic to 4 in PVC to get radon below 2 consistently. Oddly my bedroom has higher levels of Radon than the basement as the radon pipe passes through the wall with the fireplace chimney. Perhaps the PVC pipe wasn't sealed well.