Who knows technology?
I should know better than to presume anything when someone is speaking about their “furnace,” because what they most frequently mean is “the thing that makes heat.” I was recently asked about a home heater replacement by a relative who is the chief engineer at a major communications company. His question was, “should I replace my furnace to save energy?” I inquired about the efficiency and he replied 88%, which is pretty good for an oil-fired furnace, so I told them that was probably the best they could do. Then I was asked, “what about our hot water heater?,” which was described as “a tankless type fed off the furnace.” At that point I realized that my friend wasn’t using accurate language and that was causing me to give him bad advice. He in fact has a high-mass oil boiler with an indirect fired hot water tank, and since the boiler is near the end of its useful life, he does have an opportunity to replace it with a higher performance boiler.