So....are these contractor guys good?
~sip~
Seem to be--they checked for updraft and the detector noted a high level of CO. They took the flue apart and have been pulling grass & twigs out of flue for the past half-hour. Dang--the cap must have blown off the water heater/boiler portion of the flue; I have the chimney cleaned every August and the chimney sweeps didn't say a thing about any blockage. Why the good Lord keeps watching out for OB and me is a mystery.