Radon Charcoal Canisters

I am a new inspector starting out, located in MN. We are in a zone 1 radon area and I have to imagine most real estate transactions are demanding a radon test. My question is, are the charcoal canisters a thing of the past? Do pretty much all clients/agents want a CRM test nowadays? I have read every post on this board related to radon and it seems most posters here are doing CRM. I sure wouldn’t mind starting with canisters if they are still acceptable. Opinions?

Done properly, they are still acceptable.

Charcoal canisters give good results. Used to use them, now I use the Rad Elec system. Both of those systems give a result for the total exposure time (then averaged for 2 co-placed units). The CRMs sample at most once every ten minutes and give an average of the samples (6x48 or less). While it may look like the CRMs have more samples, the electret and charcoal devices change (measure) continuously over the test period (48 hours).

Charcoal you have to send out for the results. Electrets or CRMs can furnish results as soon as the test completes. Any equipment you own has to be calibrated annually and you need a QA program to assure your getting accurate results.

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Robert, I have looked at the Rad Elec system a little bit. It just seems a little expensive to get started in. Do you use Rad Elec’s SPER-1E reader? It alone is $2200 and they also recommend it gets sent in for calibration annually. Also, what is the purpose for the nitrogen cleaning kit included in their starter package? Thanks for the info.

Yes it is a little expensive. The reader allows me to give results the same day the test is completed. They are also located about 30 minutes from me and have great customer service. The nitrogen kit is for dusting the electrets and holders before testing and for QA. Nitrogen is a dry inert gas and is used extensively for cleaning lab grade equipment. The gas is cheap, the bottle (you have to buy) was about $100.00.

I believe they have a mail in program, but I don’t know what the turn around time will be for your location. Your best bet, to get started, is to use charcoal canisters until you decide if its lucrative in your market.

That’s exactly what I would like to do. Start with a lower cost system like charcoal until I can determine the demand not only for my inspection service, but also for radon testing. My dilemma is that if I can’t offer the radon results instantly, that may effect the demand negatively. It’s probably a predicament many new inspectors in high radon zones have to contend with I guess.

Good thinking, Ryan! :+1:


Take a look at the Corentium Pro units. About $1,300 each. Annual calibration is $220 from Bowser-Morner in Ohio. Easy to use and provide instant results at test completion. Canisters are still acceptable but have no means of determining if they have been tampered with by a seller. I have also done a side by side test with canisters vs CP and the difference was 10 pc/L! Canisters are outdated IMO. I mean technically you can ride a horse to work…

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… and you just assumed the CRM was correct having no other way to verify. Charcoal tests are accurate as long as done correctly, hardly outdated.

I would take the lab certified and calibrated machine over the canister any day Bob

Ryan I recommend purchasing at least one CRM. Two or three would be better. The issue is turnaround time. Everyone is in a hurry and they do not want to wait for you to send the canisters out to the lab and wait for the test results. Like it or not it’s about providing a service and keeping everyone happy. I understand it’s a big expense expecially when starting out but if you purchase one or more machines you will also be motovated to upsell every chance you get. Do keep a few canisters for those homes in the “special” locations and as backup if all your machines are in use. Spend the money and you will see a return. Just look at what other inspectors in your area are offering. You can get new machines for about $1000 maybe less. Some of the manufactures offer discounts and run periodic specials. You could also look for an older used device from an inspector that has upgraded.


The Corentium Pro is on my short list. They also offer a $99/mo. rental program. I really like the look of their reports. They should have a rent to own program!

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You will make your money back pretty quick on them. I have 4 now. They have the best reports and the anti-tamper features are important. If you use a canister, nothing prevents a seller from setting the canister outside until an hour before you come back. Seller can’t do that with a CP. They measure the temperature, humidity, and barometric pressure, and also have a motion sensor.

I use the Corentium pro as well. I chose to rent mine for a 6 month commitment its $99 a month payable monthly. I chose that to decide of i liked the system and to avoid a high startup cost. As well as test the market to see if I needed it. My market is hit or miss. Some definitely want it others think its hocus pocus stuff. One test a month pays for the unit for me and anymore are pure profit. Better to have than not have in my book.

You can lease from Radalink. If you see it’s not a market then return the monitor.