On a combustion test. Best you'll get is 78%. Still sounds great right? Well, its not. Thats only they efficiency while its burning gas. When its not burning gas, is when its real inefficiency shows up. That old burner is and dilution kit is letting large amounts of air go up through your chimney. And that is where the AFUE shows how inefficient it is. it Probably anywhere from 40 to 55% AFUE(Annual Fuel Utilization Efficiency).
Kind of like the EPA mileage estimates for cars.
30 MPG highway(your gas burner burning gas at a steady state/24/7.
17 MPG city(your gas burner cycling on and off, still wasting house heat while not burning gas, similar to a car idling at a red light).
1220 for heat and hot water for 1200 sq ft house? That engineer didn't give a rats butt about your bills.
PS: If that old timer can prove it. Have him run a combustion efficiency test. And post his combustion reading here. I'll tell you if he is fudging his reading or not. I worked on a lot of those converted units already. And they are not as efficient as some "techs" tell people.
Its also possible to replace that dinosaur with a new 95%, without running new ducts(done it to a couple places already). But it will still give you a lower resell value when you go to sell the house. Specially since if the buyer wants central A/C. They have to pay to have a duct system installed anyway.
I would leave it in the "corner" of your basement. You will be the only house on the block with heat (shovel coal in) when the electricity grid goes down from a major power surge or ice storm.
Famous last words!
I've got all the sheet metal and other stuff pulled off. This thing is a beast....between the air blower and oil blower, I think there's at least 100 lbs in metal, plus all the sheet metal.
The big red vessel is another story. I don't know if I can even get it off the ground with a dolly. It was barely able to rock it back and forth to put a small brick under it. And if I could get it moving, it don't think it will fit through the door. So what are my options now? Take a BFH to it?