After having the furnace checked out, it turned out that the main ventilator motor is kaput. Given the cost of replacing a major component and the fact that the furnace is 13 years old (out of a 15-year rated life expectancy), we decided to take the plunge and get it replaced. Supposedly, the new unit is expected to last 30 years (and is fully warrantied, parts and labor, for 10) and efficient enough to recoup some of the cost over time. It's an expense I could do without, but fortunately not a bank-breaker.

The really annoying thing is that the earliest appointment we could get for installing the new unit is Monday morning. We got an electric space heater as a stopgap; if the new unit works as advertised, it can be set aside or lent out if anybody else around here needs one.