Simple, effective,and built like a tank

The product I have is actually a DC-40-SX purchased 15 years ago. It has supplied 90% of our heat load in a 2200 square foot (I'm in the USA) house in the north midwest (northern Ohio). After all this use, it is still firing up nicely, with the only real maintenance periodic cleaning and somewhat rebuilding the nozzle which became worn after 7 years making the slot too large so the combustion at lower outputs was smoky. And now after 15 years the extraction fan is getting weak. But overall this is one of the best made products I've ever owned. I budgeted it based on hoping for 10 years of performance and I won't be surprised if this makes it to 20 or more. Thank you Atmos designers and workers for such a great and wonderfully "overbuilt" boiler.