Old house- old ducts. The old oil heater did nothing but pump out more smoke than a Midwest steel mill. Got the new furnace but was a bit nervous about having someone clean the ducts.
I have lung disease and had the ducts cleaned once before. I got a couple of yokels who hooked it up backwards and I got Legionnaires Disease. No kidding.
I got a solid recommend for Northwest Duct and they were even better than that. The difference was immediate, the fuel bill cut in half! The technician was through, knowledgeable and very pleasant. On top of that, he was half the price of the other guys.