1980 Repco Natural Gas boiler question

I have a 1980 Repco Boiler and took the output (138,000 btu) devided by input (175,000 btu) and get € . is this the efficiency? Wouldn't a new standard cast iron boiler of € efficiency be the same? Also, how would i flush sediment / scale out of it? Any feedback is much appreciated. Also, are older American Standard boilers any good? I was given a smaller 130,000 btu unit and am thinkng of cleaning it up and replacing the repco. I think it's around the same age maybe older???




thanks

Servicepcrc

Here's what you do if you're going to replace your boiler no matter what. Take the time to do what's called a heat loss calculation on your house. You can find a free program a heatinghelp.com and download it. It will amaze you as to how little it probably takes to heat your house. I find that virtually 100% of the boilers we replace for people are oversized. Installing what is actually needed for your house instead of just sizing based on what's there will save you many many $$$ for the life of the boiler. Think of it for a minute, have you ever heard your boiler running nonstop even for an hour? Probably not. The old school installers thought bigger was better and that's not the case at all. The more your boiler cycles off/on the worse the efficiency is. Steady state performance is how modulating/condensing boilers of today can cut your fuel costs from 30-50% vs a cast iron model.

Same phosolopy for the automotive engine. Where do automobiles get the best milage? Highway, steady speed. Worst? City, constant cycling