A couple of weeks ago, I did my annual pre-heating season ritual of flushing my 42 year-old Weil-McLain steam boiler in preparation for the ceremonial relighting of the pilot light. I learned later from a plumber that you shouldn't flush a cold boiler because the fresh incoming water will leave chemical deposits. It was academic in this case however because the boiler drained dry.
WTF? The low water cutoff (LWCO)/autofeed should have replenished the boiler with fresh water. It didn't. Granted, the LWCO looks like some sort of World War 2-era device and it had never been serviced since I bought the house so I wasn't surprised that it had failed. I called the most knowledgeable plumber I knew in the neighborhood. If ever there was a plumbing geek, it's him. He even collects old boiler doors as a hobby. But he also has a reputation for both being very expensive and very hard-to-get. He even charges for estimates.
True to his rep, it took a week to get him to my place. When he arrived he stared at the boiler and the LWCO for about sixty seconds and said it would cost $1500 to replace the LWCO. But he didn't recommend it. He pointed me to several areas of rust and some funky insulation on the boiler and said that it probably wouldn't last the heating season. Furthermore, if he replaced the LWCO it wouldn't be compatible with any new boiler he would install so I would be throwing away $1500.
He opened a nicely bound, four color catalog of boilers and showed me what I needed: a new boiler. He showed me the price printed next to it: $6558! He could see the blood draining from my face and reminded me that that was the installed price. But I would also need a new autofeed ($700) and $200 to pay an electrician to hook up the existing two-wire BX to the emergency cut-off switch. The numbers kept building to the final cost: $7400! If there are no unexpected problems, that is. Then he handed me a bill for $54.38 for the estimate before leaving me to deal with the same problem I called him about.