The EPA Home Buyer’s and Seller’s Guide to Radon (http://www.epa.gov/radon/pdfs/hmbuygud.pdf), page 21, under the Radon Testing Checklist says:
“Operate the home’s heating and cooling systems normally during the test. For tests lasting less than one week, operate only air-conditioning units which recirculate interior air.”
For those not understanding why radon typically enters a home, it is called “Stack Effect”. When warm air inside the home naturally rises, a “void” is created in the lower parts of the structure. Thus, the house looks for makeup air to fill this void. It could be outside air coming under the door or leaky windows in the older house, but could also be through foundation cracks, cracks in the floor above crawl spaces, etc. where radon might be lying in wait. In the latter case, radon is sucked into the house and then slowly rises along with the warm air, so it gets circulated throughout the house. During cold weather, warm air rises faster inside and the suction increases, which is the major reason why radon levels in colder parts of the country rise in the winter. It is compounded when we keep all windows and doors shut tight or winterize the house to keep the cold air out, which means that the majority of the makeup air comes from soil gasses. (Moisture also comes along for the ride, which is why radon mitigation can also lower the musty, mildewy smells in the basement too.)
The point that I am trying to make is that failure to run heating and/or systems “normally”, could cause unusual air flow patterns inside. A false low reading, which could be blamed on the “expert” who did the radon test, could comeback to haunt you. Unless you’re into leaving your assests hanging out for the taking…I would advise that you carefully read and follow the testing protocols. (http://www.epa.gov/radon/pubs/)
Air Chek, Inc.