What should I read next?

Here's what he said.

When you quote that next steam boiler-replacement job, suggest a king valve and a return valve to your client. A king valve goes on the pipe that leads from the header to the steam main. You’ll need more than one if you have more than one steam main leaving the header. The return valve goes (you guessed it) on the wet return, just before it meets the Hartford Loop. You’ll also put a full-port ball valve in the boiler’s mud leg.
You like that name? Mud leg? I do too. I like it because it describes perfectly what goes on in the bottom of a steam boiler that serves an old steam system. Here we have pipes, valves, fitting and radiators that are perhaps 100 years old. Every steam-heating system is open to the atmosphere. When you wet iron and steel and then expose it to the air you get rust. And when you let steam, moving at 60 mph, through those pipes, all that rust gets shoved down the line and winds up at the low point in the system, which is the boiler’s mud leg. Let enough mud accumulate and you’ll lose the circulation though the boiler. Lose the circulation and you lose the boiler.
So there you are with the client. You’re there because the old boiler isn’t working anymore. Maybe it failed because of mud. So you suggest the king valve, the return valve and the full-port ball valve on the mud leg. You explain that you’ll come back each year to close the king valve and the return valve. That will allow you to isolate the boiler from the system and build about 10-psi pressure inside of it. You can’t do that without the king valve and the return valve. You’ll explain that once you have that 10-psi pressure, you’ll open that big full-port ball valve on the mud leg and blow out a year’s worth of crap. The extra expense of those three valves now will add decades to the life of this boiler.

I don't think my current boiler has this set up, and I think this may have led/contributed to my boiler's demise.