There is an alternative to the Daisy Ductless, and in some instances it is highly successful, but in some other construction, it does not perform satisfactorily. However, it is much more labor intense, requires very careful workmanship and is more expensive. The benefit is that it is very inexpensive to operate and it is almost completely free of undesirable humidity increase issues. Wayne Dean invented and perfected it over a period of several years. It is called ASAPDB which is the acronym for Above Slab Air Pressure Differential Barrier Technology.
Successful functionality depends upon the following:
Very high quality air conditioning duct installation and connections. Excellent workmanship with minimal duct leakage is required.
An airtight inner pressure envelope achieved by way of an excellent drywall installation.
An air handler return that is completely isolated from the interstitial wall space, often meaning that there are absolutely no holes in the walls, ceiling and floor of the air handler closet which will allow the air handler to suck radon-rich interstitial wall space air through such openings and into the conditioned air air stream.
A condensate line that includes a proper P-trap and is connected to daylight without any connection to a drywell, french drain, or soil
An erroneous critique of this technology by a licensed professional engineer demonstrates the lack of knowledge and understanding of this technology by even the most educated “experts.” His comment was that the system could not work because radon is heavier than air and if it were to be extracted, it would need to be done from floor level. He totally overlooked or disregarded the intentionally-created air pressure differential with higher air pressure in the breathing zone pushing back against and preventing radon entry from the reduced air pressure in the interstitial wall space. There is no substitute for a curious mind and extensive field experience. The testimonial is from a PhD university professor of neural linguistics with a perfect and complete understanding of the ASAPDB technology.
SEE: an ASAPDB diagram and testimonial