On Wed, 27 Jun 2012 10:35:36 -0400, Bryce wrote:

Thanks for your comments.

We are the sellers and in a neighborhood in decline, so we
are anxious to complete the sale: tough to find buyer and we
already have a new house awaiting.

Radon test was done in the middle of the house with A/C
running. Downdraft furnace (in interior room near one end of
house) feeds conditioned air through metal ducts under the
slab, which is about 2' above grade, no crawl space. No
vents through the foundation walls. Return air to furnace
via ducts in attic. House was built in 1960.

Remediation contractor (not affiliated with inspector to our
knowledge) proposes to install suction system next to
furnace and test afterward. Cost ~$1000, "30 year guarantee"

I have a hunch that the suction will be overpowered by leaks
in the heating ducts.

This is a good place for it. The chimney chase can then be used for the pipe,
up to the roof. The suction is from under the slab so any leaks in the
heating ducts are irrelevant.

For sure, we will run A/C during test, pay by credit card.

Paranoid is sometimes justified but this plan has a 99% success rate. Radon
remediation isn't difficult. You'll be fine.