"Mark Modrall" wrote in message
...
Hi...

The oil company repair guy was here servicing our old furnace the other
day... He said that it's running at 79% efficiency (however he measured
it).

That's 'steady state' efficiency. It's not AFUE (annual fuel utilization
efficiency). If he read a 79% efficiency, you equilivent AFUE would be
around 62-65%.